diff --git a/CHANGELOG.md b/CHANGELOG.md
index b15914a..800e829 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## Unreleased
 
 - getStats() for empty trees fails. [#36](https://github.com/tzaeschke/phtree/pull/36)
+- Fix some warnings. [#37](https://github.com/tzaeschke/phtree/pull/37)
 
 ## 2.8.0 - 2023-07-29
  
diff --git a/src/main/java/ch/ethz/globis/phtree/nv/PhTreeNVSolidF.java b/src/main/java/ch/ethz/globis/phtree/nv/PhTreeNVSolidF.java
index bed086f..b3f2f2a 100644
--- a/src/main/java/ch/ethz/globis/phtree/nv/PhTreeNVSolidF.java
+++ b/src/main/java/ch/ethz/globis/phtree/nv/PhTreeNVSolidF.java
@@ -169,7 +169,7 @@ public PHREntryIterator queryInclude(double[] lower, double[] upper) {
 		long[] lLow = new long[lower.length << 1];
 		pre.pre(lower, lower, lLow);
 		pre.pre(upper, upper, lUpp);
-		return new PHREntryIterator((PhIteratorNV) pht.query(lLow, lUpp), DIM);
+		return new PHREntryIterator(pht.query(lLow, lUpp), DIM);
 	}
 	
 	/**
@@ -183,7 +183,7 @@ public PHREntryIterator queryIntersect(double[] lower, double[] upper) {
 		long[] lLow = new long[lower.length << 1];
 		pre.pre(MIN, lower, lLow);
 		pre.pre(upper, MAX, lUpp);
-		return new PHREntryIterator((PhIteratorNV) pht.query(lLow, lUpp), DIM);
+		return new PHREntryIterator(pht.query(lLow, lUpp), DIM);
 	}
 	
 	public class PHREntryIterator implements Iterator<PHREntry> {
diff --git a/src/main/java/ch/ethz/globis/phtree/nv/PhTreeVProxy.java b/src/main/java/ch/ethz/globis/phtree/nv/PhTreeVProxy.java
index e0ab43e..a4fc5b0 100644
--- a/src/main/java/ch/ethz/globis/phtree/nv/PhTreeVProxy.java
+++ b/src/main/java/ch/ethz/globis/phtree/nv/PhTreeVProxy.java
@@ -34,7 +34,7 @@ public PhTreeVProxy(int dim) {
 	}
 	
 	public PhTreeVProxy(PhTree<Object> tree) {
-		this.tree = (PhTree<Object>) tree;
+		this.tree = tree;
 	}
 	
 	@Override
diff --git a/src/main/java/ch/ethz/globis/phtree/util/BitsInt.java b/src/main/java/ch/ethz/globis/phtree/util/BitsInt.java
index 8c87aae..e939026 100644
--- a/src/main/java/ch/ethz/globis/phtree/util/BitsInt.java
+++ b/src/main/java/ch/ethz/globis/phtree/util/BitsInt.java
@@ -168,7 +168,7 @@ public static void insertBits(int[] ba, final int start, final int nBits) {
 			ba[dstByteStart] = (ba[dstByteStart] & ~mask0) |
 					(Integer.rotateRight(ba[srcByteStart], localShift) & mask0);
 			//write second part
-			int mask1 = (int) mask0 >>> -srcLocalStart; //(UNIT_BITS-srcLocalStart);
+			int mask1 = mask0 >>> -srcLocalStart; //(UNIT_BITS-srcLocalStart);
 			ba[dstByteStart] = (ba[dstByteStart] & ~mask1) | ((buf1 >>> localShift) & mask1);
 		} else {
 			//write first part
@@ -359,7 +359,7 @@ public static void copyBitsLeft1(int[] src, int posSrc, int[] dst, int posDst, i
 				//TODO? if (localEnd==0) localEnd==32;
 				int leftMask = (int) (dstLocalEnd==0 ? UNIT_0xFF : ~(UNIT_0xFF >>> dstLocalEnd)); // e.g. 1111.1110
 				int rightMask = (int) (UNIT_0xFF >>> (dstLocalEnd-srcLocalEnd));
-				int maskPost = (int) leftMask & rightMask;
+				int maskPost = leftMask & rightMask;
 				//TODO
 				//TODO local mask should go from dstLocalStart to dstLocalEnd only.
 				//TODO
diff --git a/src/main/java/ch/ethz/globis/phtree/util/JmxTools.java b/src/main/java/ch/ethz/globis/phtree/util/JmxTools.java
index 7fbb592..a4652fb 100644
--- a/src/main/java/ch/ethz/globis/phtree/util/JmxTools.java
+++ b/src/main/java/ch/ethz/globis/phtree/util/JmxTools.java
@@ -212,7 +212,8 @@ private static void processNotification(ObjectName name) {
 		totalDiff += mi.diff;
 		totalTime += mi.duration;
 	}
-	
+
+	@SuppressWarnings("unchecked")
 	public static void gcCheck() {
 		try {
 			MBeanServer server = ManagementFactory.getPlatformMBeanServer();
diff --git a/src/main/java/ch/ethz/globis/phtree/util/Refs.java b/src/main/java/ch/ethz/globis/phtree/util/Refs.java
index de7d7c0..efc4157 100644
--- a/src/main/java/ch/ethz/globis/phtree/util/Refs.java
+++ b/src/main/java/ch/ethz/globis/phtree/util/Refs.java
@@ -9,6 +9,7 @@
 import java.io.IOException;
 import java.io.ObjectInput;
 import java.io.ObjectOutput;
+import java.lang.reflect.Array;
 import java.util.Arrays;
 
 import ch.ethz.globis.phtree.PhTreeHelper;
@@ -140,7 +141,7 @@ public static <T> T[] arrayCreate(int size) {
      * @return Same array or expanded array.
      * @param <T> array type
      */
-    @Deprecated
+    // TODO remove? was @Deprecated
     public static <T> T[] arrayEnsureSize(T[] oldA, int requiredSize) {
     	if (isCapacitySufficient(oldA, requiredSize)) {
     		return oldA;
@@ -177,8 +178,8 @@ public static <T> T[] arrayClone(T[] oldA) {
     private static <T> boolean isCapacitySufficient(T[] a, int requiredSize) {
     	return a.length >= requiredSize;
     }
-    
-    @Deprecated
+
+	// TODO remove? was @Deprecated
     @SuppressWarnings("unchecked")
 	public static <T> T[] arrayTrim(T[] oldA, int requiredSize) {
     	int reqSize = calcArraySize(requiredSize);
@@ -191,7 +192,7 @@ public static <T> T[] arrayTrim(T[] oldA, int requiredSize) {
     	return newA;
     }
 
-    @Deprecated
+	// TODO remove? was @Deprecated
 	public static <T> void insertAtPos(T[] values, int pos, T value) {
 		copyRight(values, pos, values, pos+1, values.length-pos-1);
 		values[pos] = value;
@@ -216,8 +217,8 @@ public static <T> T[] insertSpaceAtPos(T[] values, int pos, int requiredSize) {
 		copyRight(values, pos, dst, pos+1, requiredSize-1-pos);
 		return dst;
 	}
-	
-	@Deprecated
+
+	// TODO remove? was @Deprecated
 	public static <T> void removeAtPos(T[] values, int pos) {
 		if (pos < values.length-1) {
 			copyLeft(values, pos+1, values, pos, values.length-pos-1);
@@ -300,5 +301,14 @@ public static <T> T[] read(ObjectInput in) throws IOException {
 		}
 		return ret;
 	}
-	
+
+	@SuppressWarnings("unchecked")
+	public static <T> T[] newArray(int size) {
+		return (T[]) new Object[size];
+	}
+
+	@SuppressWarnings("unchecked")
+	public static <T> T[] newArray(Class<T> c, int size) {
+		return (T[]) Array.newInstance(c, size);
+	}
 }
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/NodeIteratorListReuse.java b/src/main/java/ch/ethz/globis/phtree/v11/NodeIteratorListReuse.java
index d202c74..bea6a11 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/NodeIteratorListReuse.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/NodeIteratorListReuse.java
@@ -11,6 +11,7 @@
 import ch.ethz.globis.pht64kd.MaxKTreeI.NtEntry;
 import ch.ethz.globis.phtree.PhEntry;
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 import ch.ethz.globis.phtree.v11.nt.NtIteratorMask;
 
 /**
@@ -31,7 +32,8 @@ public class NodeIteratorListReuse<T, R> {
 	
 	private class PhIteratorStack {
 		@SuppressWarnings("unchecked")
-		private final NodeIterator[] stack = new NodeIteratorListReuse.NodeIterator[64];
+		private final NodeIterator[] stack =
+				Refs.newArray(NodeIteratorListReuse.NodeIterator.class, 64);
 		private int size = 0;
 
 
@@ -70,14 +72,9 @@ private final class NodeIterator {
 
 		/**
 		 * 
-		 * @param node
-		 * @param dims
-		 * @param valTemplate A null indicates that no values are to be extracted.
+		 * @param node node
 		 * @param lower The minimum HC-Pos that a value should have.
-		 * @param upper
-		 * @param minValue The minimum value that any found value should have. 
-		 * 				   If the found value is lower, the search continues.
-		 * @param maxValue
+		 * @param upper The maximum HC-Pos that a value should have.
 		 */
 		void reinitAndRun(Node node, long lower, long upper) {
 			this.node = node;
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorFullNoGC.java b/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorFullNoGC.java
index eb657e7..5db37d4 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorFullNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorFullNoGC.java
@@ -11,6 +11,7 @@
 import ch.ethz.globis.phtree.PhEntry;
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhExtent;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * This PhIterator uses a loop instead of recursion in findNextElement();. 
@@ -32,7 +33,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack() {
-			stack = new NodeIteratorFullNoGC[PhTree11.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorFullNoGC.class, PhTree11.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorNoGC.java b/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorNoGC.java
index 2f5aad8..06f4bbd 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/PhIteratorNoGC.java
@@ -12,6 +12,7 @@
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhQuery;
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * This PhIterator uses a loop instead of recursion in findNextElement();. 
@@ -33,7 +34,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack() {
-			stack = new NodeIteratorNoGC[PhTree11.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorNoGC.class, PhTree11.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/PhQueryKnnMbbPPList.java b/src/main/java/ch/ethz/globis/phtree/v11/PhQueryKnnMbbPPList.java
index a9e2dab..4fd1297 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/PhQueryKnnMbbPPList.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/PhQueryKnnMbbPPList.java
@@ -15,6 +15,7 @@
 import ch.ethz.globis.phtree.PhFilterDistance;
 import ch.ethz.globis.phtree.PhTree.PhExtent;
 import ch.ethz.globis.phtree.PhTree.PhKnnQuery;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * kNN query implementation that uses preprocessors and distance functions.
@@ -302,7 +303,7 @@ void reset(int newSize, long[] center) {
 			this.center = center;
 			maxDistance = Double.MAX_VALUE;
 			if (data == null) {
-				data = new PhEntryDist[newSize];
+				data = Refs.newArray(PhEntryDist.class, newSize);
 				distData = new double[newSize];
 				for (int i = 0; i < data.length; i++) {
 					data[i] = createEntry();
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/PhTree11.java b/src/main/java/ch/ethz/globis/phtree/v11/PhTree11.java
index 4ca2833..272aa94 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/PhTree11.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/PhTree11.java
@@ -133,6 +133,9 @@ public int size() {
 
 	@Override
 	public PhTreeStats getStats() {
+		if (getRoot() == null) {
+			return new PhTreeStats(DEPTH_64);
+		}
 		return getStats(0, getRoot(), new PhTreeStats(DEPTH_64));
 	}
 
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMask.java b/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMask.java
index 6a190e3..4ae1b35 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMask.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMask.java
@@ -11,6 +11,7 @@
 import ch.ethz.globis.pht64kd.MaxKTreeI;
 import ch.ethz.globis.pht64kd.MaxKTreeI.NtEntry;
 import ch.ethz.globis.pht64kd.MaxKTreeI.PhIterator64;
+import ch.ethz.globis.phtree.util.Refs;
 
 
 /**
@@ -34,7 +35,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack(int depth) {
-			stack = new NtNodeIteratorMask[depth];
+			stack = Refs.newArray(NtNodeIteratorMask.class, depth);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMinMax.java b/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMinMax.java
index cf47fdd..cf0b8db 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMinMax.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/nt/NtIteratorMinMax.java
@@ -11,6 +11,7 @@
 import ch.ethz.globis.pht64kd.MaxKTreeI;
 import ch.ethz.globis.pht64kd.MaxKTreeI.NtEntry;
 import ch.ethz.globis.pht64kd.MaxKTreeI.PhIterator64;
+import ch.ethz.globis.phtree.util.Refs;
 
 
 /**
@@ -34,7 +35,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack(int depth) {
-			stack = new NtNodeIteratorMinMax[depth];
+			stack = Refs.newArray(NtNodeIteratorMinMax.class, depth);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v11/nt/NtNodePool.java b/src/main/java/ch/ethz/globis/phtree/v11/nt/NtNodePool.java
index bf8225d..1c3bc75 100644
--- a/src/main/java/ch/ethz/globis/phtree/v11/nt/NtNodePool.java
+++ b/src/main/java/ch/ethz/globis/phtree/v11/nt/NtNodePool.java
@@ -7,6 +7,7 @@
 package ch.ethz.globis.phtree.v11.nt;
 
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * Manipulation methods and pool for NtNodes.
@@ -15,8 +16,8 @@
  */
 public class NtNodePool {
 	
-	private static final NtNode<?>[] POOL = 
-			new NtNode[PhTreeHelper.MAX_OBJECT_POOL_SIZE];
+	private static final NtNode<?>[] POOL =
+			Refs.newArray(NtNode.class, PhTreeHelper.MAX_OBJECT_POOL_SIZE);
 	private static int poolSize;
 	/** Nodes currently used outside the pool. */
 	private static int activeNodes = 0;
diff --git a/src/main/java/ch/ethz/globis/phtree/v13/NodeIteratorListReuse.java b/src/main/java/ch/ethz/globis/phtree/v13/NodeIteratorListReuse.java
index d8a5c85..4cec934 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13/NodeIteratorListReuse.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13/NodeIteratorListReuse.java
@@ -22,6 +22,7 @@
 import java.util.List;
 
 import ch.ethz.globis.phtree.PhEntry;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * A NodeIterator that returns a list instead of an Iterator AND reuses the NodeIterator.
@@ -41,7 +42,8 @@ public class NodeIteratorListReuse<T, R> {
 	
 	private class PhIteratorStack {
 		@SuppressWarnings("unchecked")
-		private final NodeIterator[] stack = new NodeIteratorListReuse.NodeIterator[64];
+		private final NodeIterator[] stack =
+				Refs.newArray(NodeIteratorListReuse.NodeIterator.class,64);
 		private int size = 0;
 
 
diff --git a/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorFullNoGC.java b/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorFullNoGC.java
index 008b939..cc32292 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorFullNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorFullNoGC.java
@@ -13,6 +13,7 @@
 import ch.ethz.globis.phtree.PhEntry;
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhExtent;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * This PhIterator uses a loop instead of recursion in findNextElement();. 
@@ -34,7 +35,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		PhIteratorStack() {
-			stack = new NodeIteratorFullNoGC[PhTree13.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorFullNoGC.class, PhTree13.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorKnn.java b/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorKnn.java
index cf76b1b..00c47cc 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorKnn.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorKnn.java
@@ -66,7 +66,7 @@ public boolean isValid(int bitsToIgnore, long[] prefix) {
     }
 
     @Override
-    public PhKnnQuery<T> reset(int minResults, PhDistance distFn, long[] center) {
+    public PhKnnQuery<T> reset(int minResults, PhDistance distFn, long ... center) {
         this.center = center;
         this.distFn = distFn == null ? this.distFn : distFn;
         this.currentDistance = Double.MAX_VALUE;
diff --git a/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorNoGC.java b/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorNoGC.java
index 21258d7..ff0ed1f 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13/PhIteratorNoGC.java
@@ -14,6 +14,7 @@
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhQuery;
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * This PhIterator uses a loop instead of recursion in findNextElement();. 
@@ -35,7 +36,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		PhIteratorStack() {
-			stack = new NodeIteratorNoGC[PhTree13.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorNoGC.class, PhTree13.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v13/PhTree13.java b/src/main/java/ch/ethz/globis/phtree/v13/PhTree13.java
index 1e2ad93..9833f69 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13/PhTree13.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13/PhTree13.java
@@ -44,46 +44,46 @@
 
 /**
  * n-dimensional index (quad-/oct-/n-tree).
- *
+ * <p>
  *
  * Version 13:
  * Version 13SP: Based on Version 11. Some optimizations, for example store HC-Pos in postFix.
  * 				Version 13SP has 'synchronized' object pools and NT nodes for high dim.
  * 			    Version 13 has local unsynchronized pools. It also has the NT tree removed.
- * 
+ * <p>
  * Version 12: This was an attempt at a persistent version.
- * 
+ * <p>
  * Version 11: Use of NtTree for Nodes
  *             'null' values are replaced by NULL, this allows removal of AHC-exists bitmap
  *             Removal of recursion (and reimplementation) for get/insert/delete/update 
- * 
+ * <p>
  * Version 10b: Moved infix into parent node.
- * 
+ * <p>
  * Version 10: Store sub-nodes and postfixes in a common structure (one list/HC of key, one array)
  *             Advantages: much easier iteration through node, replacement of sub/post during 
  *             updates w/o bit shifting, can check infix without accessing sub-node (good for I/O).
- * 
+ * <p>
  * Version 8b: Extended array pooling to all arrays
- * 
+ * <p>
  * Version 8: Use 64bit depth everywhere. This should simplify a number of methods, especially
  *            regarding negative values.
- * 
+ * <p>
  * Version 7: Uses PhEntry to store/return keys.
- *
+ * <p>
  * Version 5: moved postCnt/subCnt into node.
- *
+ * <p>
  * Version 4: Using long[] instead of int[]
- *
+ * <p>
  * Version 3: This includes values for each key.
- *
+ * <p>
  * Storage:
  * - classic: One node per combination of bits. Unused nodes can be cut off.
  * - use prefix-truncation: a node may contain a series of unique bit combinations
- *
+ * <p>
  * Hypercube: expanded byte array that contains 2^DIM references to sub-nodes (and posts, depending 
  * on implementation)
  * Linearization: Storing Hypercube as paired array of index / non_null_reference 
- *
+ * <p>
  * See also : T. Zaeschke, C. Zimmerli, M.C. Norrie; 
  * "The PH-Tree -- A Space-Efficient Storage Structure and Multi-Dimensional Index", 
  * (SIGMOD 2014)
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/Node.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/Node.java
index e6a40c0..1841eaa 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/Node.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/Node.java
@@ -146,7 +146,7 @@ <T> PhEntry<T> createNodeEntry(long[] key, T value) {
 		return new PhEntry<>(key, value);
 	}
 	
-	private void discardNode(PhTree13SP tree) {
+	private void discardNode() {
 		Bits.arrayReplace(ba, null);
 		Refs.arrayReplace(values, null);
 		entryCnt = 0;
@@ -539,7 +539,7 @@ private Object deleteAndMergeIntoParent(int pinToDelete, long hcPos, long[] key,
 			parent.replaceSubWithPost(pinInParent, posInParent, newPost, val2);
 		}
 
-		discardNode(tree);
+		discardNode();
 		return valueToDelete;
 	}
 
@@ -575,7 +575,7 @@ private void mergeIntoParentNt(long[] key, Node parent, PhTree13SP<?> tree) {
 			parent.replaceSubWithPost(pinInParent, posInParent, nte.getKdKey(), nte.getValue());
 		}
 
-		discardNode(tree);
+		discardNode();
 	}
 
 	/**
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/NodeIteratorListReuse.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/NodeIteratorListReuse.java
index 10c18a6..e936869 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/NodeIteratorListReuse.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/NodeIteratorListReuse.java
@@ -10,6 +10,7 @@
 
 import ch.ethz.globis.pht64kd.MaxKTreeI.NtEntry;
 import ch.ethz.globis.phtree.PhEntry;
+import ch.ethz.globis.phtree.util.Refs;
 import ch.ethz.globis.phtree.v13SynchedPool.nt.NtIteratorMask;
 
 import java.util.List;
@@ -32,7 +33,8 @@ public class NodeIteratorListReuse<T, R> {
 	
 	private class PhIteratorStack {
 		@SuppressWarnings("unchecked")
-		private final NodeIterator[] stack = new NodeIteratorListReuse.NodeIterator[64];
+		private final NodeIterator[] stack =
+				Refs.newArray(NodeIteratorListReuse.NodeIterator.class, 64);
 		private int size = 0;
 
 
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorFullNoGC.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorFullNoGC.java
index ab80264..3fb4d15 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorFullNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorFullNoGC.java
@@ -11,6 +11,7 @@
 import ch.ethz.globis.phtree.PhEntry;
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhExtent;
+import ch.ethz.globis.phtree.util.Refs;
 
 import java.util.NoSuchElementException;
 
@@ -34,7 +35,7 @@ private class PhIteratorStack {
 
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack() {
-			stack = new NodeIteratorFullNoGC[PhTree13SP.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorFullNoGC.class, PhTree13SP.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorNoGC.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorNoGC.java
index 344de1b..14346d0 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhIteratorNoGC.java
@@ -12,6 +12,7 @@
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhQuery;
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 
 import java.util.NoSuchElementException;
 
@@ -35,7 +36,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack() {
-			stack = new NodeIteratorNoGC[PhTree13SP.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorNoGC.class, PhTree13SP.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhQueryKnnMbbPPList.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhQueryKnnMbbPPList.java
index ab6214c..c7f2eea 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhQueryKnnMbbPPList.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhQueryKnnMbbPPList.java
@@ -304,7 +304,7 @@ void reset(int newSize, long[] center) {
 			this.center = center;
 			maxDistance = Double.MAX_VALUE;
 			if (data == null) {
-				data = new PhEntryDist[newSize];
+				data = (PhEntryDist[]) new Object[newSize];
 				distData = new double[newSize];
 				for (int i = 0; i < data.length; i++) {
 					data[i] = createEntry();
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhTree13SP.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhTree13SP.java
index 1044e88..7b8ca38 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhTree13SP.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/PhTree13SP.java
@@ -31,45 +31,45 @@
 
 /**
  * n-dimensional index (quad-/oct-/n-tree).
- *
+ * <p>
  * Version 13:
  * Version 13SP: Based on Version 11. Some optimizations, for example store HC-Pos in postFix.
  * 				Version 13SP has 'synchronized' object pools and NT nodes for high dim.
  * 			    Version 13 has local unsynchronized pools. It also has the NT tree removed.
- * 
+ * <p>
  * Version 12: This was an attempt at a persistent version.
- * 
+ * <p>
  * Version 11: Use of NtTree for Nodes
  *             'null' values are replaced by NULL, this allows removal of AHC-exists bitmap
  *             Removal of recursion (and reimplementation) for get/insert/delete/update 
- * 
+ * <p>
  * Version 10b: Moved infix into parent node.
- * 
+ * <p>
  * Version 10: Store sub-nodes and postfixes in a common structure (one list/HC of key, one array)
  *             Advantages: much easier iteration through node, replacement of sub/post during 
  *             updates w/o bit shifting, can check infix without accessing sub-node (good for I/O).
- * 
+ * <p>
  * Version 8b: Extended array pooling to all arrays
- * 
+ * <p>
  * Version 8: Use 64bit depth everywhere. This should simplify a number of methods, especially
  *            regarding negative values.
- * 
+ * <p>
  * Version 7: Uses PhEntry to store/return keys.
- *
+ * <p>
  * Version 5: moved postCnt/subCnt into node.
- *
+ * <p>
  * Version 4: Using long[] instead of int[]
- *
+ * <p>
  * Version 3: This includes values for each key.
- *
+ * <p>
  * Storage:
  * - classic: One node per combination of bits. Unused nodes can be cut off.
  * - use prefix-truncation: a node may contain a series of unique bit combinations
- *
+ * <p>
  * Hypercube: expanded byte array that contains 2^DIM references to sub-nodes (and posts, depending 
  * on implementation)
  * Linearization: Storing Hypercube as paired array of index / non_null_reference 
- *
+ * <p>
  * See also : T. Zaeschke, C. Zimmerli, M.C. Norrie; 
  * "The PH-Tree -- A Space-Efficient Storage Structure and Multi-Dimensional Index", 
  * (SIGMOD 2014)
@@ -139,6 +139,9 @@ public int size() {
 
 	@Override
 	public PhTreeStats getStats() {
+		if (getRoot() == null) {
+			return new PhTreeStats(DEPTH_64);
+		}
 		return getStats(0, getRoot(), new PhTreeStats(DEPTH_64));
 	}
 
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMask.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMask.java
index f3d440a..24dac6b 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMask.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMask.java
@@ -11,6 +11,7 @@
 import ch.ethz.globis.pht64kd.MaxKTreeI;
 import ch.ethz.globis.pht64kd.MaxKTreeI.NtEntry;
 import ch.ethz.globis.pht64kd.MaxKTreeI.PhIterator64;
+import ch.ethz.globis.phtree.util.Refs;
 
 import java.util.NoSuchElementException;
 
@@ -36,7 +37,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack(int depth) {
-			stack = new NtNodeIteratorMask[depth];
+			stack = Refs.newArray(NtNodeIteratorMask.class, depth);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMinMax.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMinMax.java
index 0f2ee35..ddfc089 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMinMax.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtIteratorMinMax.java
@@ -11,6 +11,7 @@
 import ch.ethz.globis.pht64kd.MaxKTreeI;
 import ch.ethz.globis.pht64kd.MaxKTreeI.NtEntry;
 import ch.ethz.globis.pht64kd.MaxKTreeI.PhIterator64;
+import ch.ethz.globis.phtree.util.Refs;
 
 import java.util.NoSuchElementException;
 
@@ -36,7 +37,7 @@ private class PhIteratorStack {
 
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack(int depth) {
-			stack = new NtNodeIteratorMinMax[depth];
+			stack = Refs.newArray(NtNodeIteratorMinMax.class, depth);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtNodePool.java b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtNodePool.java
index c3f342b..c346e7e 100644
--- a/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtNodePool.java
+++ b/src/main/java/ch/ethz/globis/phtree/v13SynchedPool/nt/NtNodePool.java
@@ -9,6 +9,7 @@
 package ch.ethz.globis.phtree.v13SynchedPool.nt;
 
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * Manipulation methods and pool for NtNodes.
@@ -16,9 +17,9 @@
  * @author ztilmann
  */
 public class NtNodePool {
-	
+
 	private static final NtNode<?>[] POOL =
-			new NtNode[PhTreeHelper.MAX_OBJECT_POOL_SIZE];
+			Refs.newArray(NtNode.class, PhTreeHelper.MAX_OBJECT_POOL_SIZE);
 	private static int poolSize;
 	/** Nodes currently used outside the pool. */
 	private static int activeNodes = 0;
diff --git a/src/main/java/ch/ethz/globis/phtree/v16/NodeIteratorListReuse.java b/src/main/java/ch/ethz/globis/phtree/v16/NodeIteratorListReuse.java
index e7eb257..8d9e303 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16/NodeIteratorListReuse.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16/NodeIteratorListReuse.java
@@ -22,6 +22,7 @@
 import java.util.List;
 
 import ch.ethz.globis.phtree.PhEntry;
+import ch.ethz.globis.phtree.util.Refs;
 import ch.ethz.globis.phtree.v16.Node.BSTEntry;
 import ch.ethz.globis.phtree.v16.bst.BSTIteratorMask;
 
@@ -43,7 +44,8 @@ public class NodeIteratorListReuse<T, R> {
 	
 	private class PhIteratorStack {
 		@SuppressWarnings("unchecked")
-		private final NodeIterator[] stack = new NodeIteratorListReuse.NodeIterator[64];
+		private final NodeIterator[] stack =
+				Refs.newArray(NodeIteratorListReuse.NodeIterator.class, 64);
 		private int size = 0;
 
 
diff --git a/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorFullNoGC.java b/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorFullNoGC.java
index 5efa772..5daf210 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorFullNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorFullNoGC.java
@@ -24,6 +24,7 @@
 import ch.ethz.globis.phtree.PhEntry;
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhExtent;
+import ch.ethz.globis.phtree.util.Refs;
 import ch.ethz.globis.phtree.util.unsynced.LongArrayOps;
 
 /**
@@ -46,7 +47,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		PhIteratorStack() {
-			stack = new NodeIteratorFullNoGC[PhTree16.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorFullNoGC.class, PhTree16.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorKnn.java b/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorKnn.java
index c1cc69b..ab357a8 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorKnn.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorKnn.java
@@ -64,7 +64,7 @@ public boolean isValid(int bitsToIgnore, long[] prefix) {
     }
 
     @Override
-    public PhKnnQuery<T> reset(int minResults, PhDistance distFn, long[] center) {
+    public PhKnnQuery<T> reset(int minResults, PhDistance distFn, long ... center) {
         this.center = center;
         this.distFn = distFn == null ? this.distFn : distFn;
         this.currentDistance = Double.MAX_VALUE;
diff --git a/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorNoGC.java b/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorNoGC.java
index 3946816..ef4f416 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16/PhIteratorNoGC.java
@@ -25,6 +25,7 @@
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhQuery;
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 import ch.ethz.globis.phtree.util.unsynced.LongArrayOps;
 
 /**
@@ -47,7 +48,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		PhIteratorStack() {
-			stack = new NodeIteratorNoGC[PhTree16.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorNoGC.class, PhTree16.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v16/PhTree16.java b/src/main/java/ch/ethz/globis/phtree/v16/PhTree16.java
index 376ce4f..f8d16f3 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16/PhTree16.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16/PhTree16.java
@@ -43,48 +43,48 @@
 
 /**
  * n-dimensional index (quad-/oct-/n-tree).
- * 
+ * <p>
  * Version 16: BST-only, directly integrated with Node
- * 
+ * <p>
  * Version 15: BST-Only
- * 
+ * <p>
  * Version 14: Removed NT (nested tree) and replaced it with hierarchical table.
- * 
+ * <p>
  * Version 13: Based on Version 11. Some optimizations, for example store HC-Pos in postFix.
- * 
+ * <p>
  * Version 12: This was an attempt at a persistent version.
- * 
+ * <p>
  * Version 11: Use of NtTree for Nodes
  *             'null' values are replaced by NULL, this allows removal of AHC-exists bitmap
  *             Removal of recursion (and reimplementation) for get/insert/delete/update 
- * 
+ * <p>
  * Version 10b: Moved infix into parent node.
- * 
+ * <p>
  * Version 10: Store sub-nodes and postfixes in a common structure (one list/HC of key, one array)
  *             Advantages: much easier iteration through node, replacement of sub/post during 
  *             updates w/o bit shifting, can check infix without accessing sub-node (good for I/O).
- * 
+ * <p>
  * Version 8b: Extended array pooling to all arrays
- * 
+ * <p>
  * Version 8: Use 64bit depth everywhere. This should simplify a number of methods, especially
  *            regarding negative values.
- * 
+ * <p>
  * Version 7: Uses PhEntry to store/return keys.
- *
+ * <p>
  * Version 5: moved postCnt/subCnt into node.
- *
+ * <p>
  * Version 4: Using long[] instead of int[]
- *
+ * <p>
  * Version 3: This includes values for each key.
- *
+ * <p>
  * Storage:
  * - classic: One node per combination of bits. Unused nodes can be cut off.
  * - use prefix-truncation: a node may contain a series of unique bit combinations
- *
+ * <p>
  * Hypercube: expanded byte array that contains 2^DIM references to sub-nodes (and posts, depending 
  * on implementation)
  * Linearization: Storing Hypercube as paired array of index / non_null_reference 
- *
+ * <p>
  * See also : T. Zaeschke, C. Zimmerli, M.C. Norrie; 
  * "The PH-Tree -- A Space-Efficient Storage Structure and Multi-Dimensional Index", 
  * (SIGMOD 2014)
diff --git a/src/main/java/ch/ethz/globis/phtree/v16hd/NodeIteratorListReuse.java b/src/main/java/ch/ethz/globis/phtree/v16hd/NodeIteratorListReuse.java
index ad50693..4fe03b0 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16hd/NodeIteratorListReuse.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16hd/NodeIteratorListReuse.java
@@ -42,7 +42,7 @@ public class NodeIteratorListReuse<T, R> {
 	
 	private class PhIteratorStack {
 		@SuppressWarnings("unchecked")
-		private final NodeIterator[] stack = new NodeIteratorListReuse.NodeIterator[64];
+		private final NodeIterator[] stack = (NodeIteratorListReuse.NodeIterator[]) new Object[64];
 		private int size = 0;
 
 
diff --git a/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorFullNoGC.java b/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorFullNoGC.java
index f5a208e..c1f711e 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorFullNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorFullNoGC.java
@@ -23,6 +23,7 @@
 import ch.ethz.globis.phtree.PhEntry;
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhExtent;
+import ch.ethz.globis.phtree.util.Refs;
 import ch.ethz.globis.phtree.util.unsynced.LongArrayOps;
 
 /**
@@ -45,7 +46,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		PhIteratorStack() {
-			stack = new NodeIteratorFullNoGC[PhTree16HD.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorFullNoGC.class, PhTree16HD.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorKnn.java b/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorKnn.java
index c53e8dc..a533ff0 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorKnn.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorKnn.java
@@ -64,7 +64,7 @@ public boolean isValid(int bitsToIgnore, long[] prefix) {
     }
 
     @Override
-    public PhKnnQuery<T> reset(int minResults, PhDistance distFn, long[] center) {
+    public PhKnnQuery<T> reset(int minResults, PhDistance distFn, long ... center) {
         this.center = center;
         this.distFn = distFn == null ? this.distFn : distFn;
         this.currentDistance = Double.MAX_VALUE;
diff --git a/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorNoGC.java b/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorNoGC.java
index fcec9af..86363a7 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16hd/PhIteratorNoGC.java
@@ -24,6 +24,7 @@
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTree.PhQuery;
 import ch.ethz.globis.phtree.PhTreeHelper;
+import ch.ethz.globis.phtree.util.Refs;
 import ch.ethz.globis.phtree.util.unsynced.LongArrayOps;
 
 /**
@@ -46,7 +47,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		PhIteratorStack() {
-			stack = new NodeIteratorNoGC[PhTree16HD.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorNoGC.class, PhTree16HD.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v16hd/PhTree16HD.java b/src/main/java/ch/ethz/globis/phtree/v16hd/PhTree16HD.java
index dfbbc61..162944d 100644
--- a/src/main/java/ch/ethz/globis/phtree/v16hd/PhTree16HD.java
+++ b/src/main/java/ch/ethz/globis/phtree/v16hd/PhTree16HD.java
@@ -47,48 +47,48 @@
 
 /**
  * n-dimensional index (quad-/oct-/n-tree).
- * 
+ * <p>
  * Version 16: BST-only, directly integrated with Node
- * 
+ * <p>
  * Version 15: BST-Only
- * 
+ * <p>
  * Version 14: Removed NT (nested tree) and replaced it with hierarchical table.
- * 
+ * <p>
  * Version 13: Based on Version 11. Some optimizations, for example store HC-Pos in postFix.
- * 
+ * <p>
  * Version 12: This was an attempt at a persistent version.
- * 
+ * <p>
  * Version 11: Use of NtTree for Nodes
  *             'null' values are replaced by NULL, this allows removal of AHC-exists bitmap
  *             Removal of recursion (and reimplementation) for get/insert/delete/update 
- * 
+ * <p>
  * Version 10b: Moved infix into parent node.
- * 
+ * <p>
  * Version 10: Store sub-nodes and postfixes in a common structure (one list/HC of key, one array)
  *             Advantages: much easier iteration through node, replacement of sub/post during 
  *             updates w/o bit shifting, can check infix without accessing sub-node (good for I/O).
- * 
+ * <p>
  * Version 8b: Extended array pooling to all arrays
- * 
+ * <p>
  * Version 8: Use 64bit depth everywhere. This should simplify a number of methods, especially
  *            regarding negative values.
- * 
+ * <p>
  * Version 7: Uses PhEntry to store/return keys.
- *
+ * <p>
  * Version 5: moved postCnt/subCnt into node.
- *
+ * <p>
  * Version 4: Using long[] instead of int[]
- *
+ * <p>
  * Version 3: This includes values for each key.
- *
+ * <p>
  * Storage:
  * - classic: One node per combination of bits. Unused nodes can be cut off.
  * - use prefix-truncation: a node may contain a series of unique bit combinations
- *
+ * <p>
  * Hypercube: expanded byte array that contains 2^DIM references to sub-nodes (and posts, depending 
  * on implementation)
  * Linearization: Storing Hypercube as paired array of index / non_null_reference 
- *
+ * <p>
  * See also : T. Zaeschke, C. Zimmerli, M.C. Norrie; 
  * "The PH-Tree -- A Space-Efficient Storage Structure and Multi-Dimensional Index", 
  * (SIGMOD 2014)
diff --git a/src/main/java/ch/ethz/globis/phtree/v8/Node.java b/src/main/java/ch/ethz/globis/phtree/v8/Node.java
index 04aea5b..a79ae6a 100644
--- a/src/main/java/ch/ethz/globis/phtree/v8/Node.java
+++ b/src/main/java/ch/ethz/globis/phtree/v8/Node.java
@@ -78,11 +78,11 @@ private static final boolean NI_THRESHOLD(int subCnt, int postCnt) {
 	protected Node(Node<T> original, int dim) {
         if (original.subNRef != null) {
             int size = original.subNRef.length;
-            this.subNRef = new Node[size];
+            this.subNRef = (Node[]) new Object[size];
             System.arraycopy(original.subNRef, 0, this.subNRef, 0, size);
         }
         if (original.values != null) {
-            this.values = (T[]) original.values.clone();
+            this.values = original.values.clone();
         }
         if (original.ba != null) {
             this.ba = new long[original.ba.length];
@@ -283,7 +283,7 @@ void addSubNode(long pos, Node<T> sub, final int DIM) {
 		}
 
 		if (subNRef == null) {
-			subNRef = new Node[2];
+			subNRef = Refs.newArray(Node.class, 2);
 		}
 
 		//decide here whether to use hyper-cube or linear representation
@@ -298,7 +298,7 @@ void addSubNode(long pos, Node<T> sub, final int DIM) {
 		//switch to normal array (full hyper-cube) if applicable.
 		if (DIM<=31 && (REF_BITS+SIK_WIDTH(DIM))*(subNRef.length+1L) >= REF_BITS*(1L<<DIM)) {
 			//migrate to full array!
-			Node<T>[] na = new Node[1<<DIM];
+			Node<T>[] na = Refs.newArray(Node.class, 1<<DIM);
 			for (int i = 0; i < bufSubCount; i++) {
 				int posOld = (int) Bits.readArray(ba, subOffsBits + i*SIK_WIDTH(DIM), SIK_WIDTH(DIM));
 				na[posOld] = subNRef[i];
@@ -328,7 +328,7 @@ void addSubNode(long pos, Node<T> sub, final int DIM) {
 		if (subNRef.length < bufSubCount+1) {
 			int newLen = bufSubCount+1;
 			newLen = (newLen&1)==0 ? newLen : newLen+1; //ensure multiples of two
-			Node<T>[] na2 = new Node[newLen];
+			Node<T>[] na2 = Refs.newArray(Node.class, newLen);
 			System.arraycopy(subNRef, 0, na2, 0, start);
 			System.arraycopy(subNRef, start, na2, start+1, len);
 			subNRef = na2;
@@ -409,7 +409,7 @@ void removeSub(long pos, final int DIM) {
 			int prePostBits_SubLHC = getBitPos_PostIndex(DIM);
 			int bia2Size = calcArraySizeTotalBits(bufPostCnt, DIM);
 			long[] bia2 = Bits.arrayCreate(bia2Size);
-			Node<T>[] sa2 = new Node[bufSubCnt];
+			Node<T>[] sa2 = Refs.newArray(Node.class, bufSubCnt);
 			int preSubBits = getBitPos_SubNodeIndex(DIM);
 			//Copy only bits that are relevant. Otherwise we might mess up the not-null table!
 			Bits.copyBitsLeft(ba, 0, bia2, 0, preSubBits);
@@ -460,7 +460,7 @@ void removeSub(long pos, final int DIM) {
 				int newLen = bufSubCnt-1;
 				newLen = (newLen&1)==0 ? newLen : newLen+1; //ensure multiples of two
 				if (newLen > 0) {
-					Node<T>[] na2 = new Node[newLen];
+					Node<T>[] na2 = Refs.newArray(Node.class, newLen);
 					System.arraycopy(subNRef, 0, na2, 0, p2);
 					System.arraycopy(subNRef, p2+1, na2, p2, len);
 					subNRef = na2;
@@ -487,8 +487,9 @@ void removeSub(long pos, final int DIM) {
 
 	/**
 	 * Compare two post-fixes. Takes as parameter not the position but the post-offset-bits.
-	 * @param pob
-	 * @param key
+	 * @param offsPostKey offsPostKey
+	 * @param hcPos hcPos
+	 * @param key key
 	 * @return true, if the post-fixes match
 	 */
 	boolean postEqualsPOB(int offsPostKey, long hcPos, long[] key) {
@@ -589,6 +590,7 @@ void addPost(long pos, long[] key, T value) {
 	 * @param offsPostKey POB: Post offset bits from getPostOffsetBits(...)
 	 * @param key
 	 */
+	@SuppressWarnings("deprecated")
 	void addPostPOB(long pos, int offsPostKey, long[] key, T value) {
 		final int DIM = key.length;
 		final int bufSubCnt = getSubCount();
@@ -614,7 +616,7 @@ void addPostPOB(long pos, int offsPostKey, long[] key, T value) {
 
 		//switch representation (HC <-> Linear)?
 		//+1 bit for null/not-null flag
-		long sizeHC = (long) ((DIM * postLen + PINN_HC_WIDTH) * (1L << DIM)); 
+		long sizeHC = (DIM * postLen + PINN_HC_WIDTH) * (1L << DIM);
 		//+DIM because every index entry needs DIM bits
 		long sizeLin = (DIM * postLen + PIK_WIDTH(DIM)) * (bufPostCnt+1L);
 		if (!isPostHC() && (DIM<=31) && (sizeLin >= sizeHC)) {
@@ -773,8 +775,6 @@ void niBuild(int bufSubCnt, int bufPostCnt, int DIM) {
 
 	/**
 	 * 
-	 * @param bufSubCnt
-	 * @param bufPostCnt
 	 * @param DIM
 	 * @param posToRemove
 	 * @param removeSub Remove sub or post?
@@ -815,7 +815,7 @@ T niDeconstruct(int DIM, long posToRemove, boolean removeSub) {
 		//switch to normal array (full hyper-cube) if applicable.
 		if (DIM<=31 && (REF_BITS+SIK_WIDTH(DIM))*newSubCnt >= REF_BITS*(1L<<DIM)) {
 			//migrate to full HC array
-			Node<T>[] na = new Node[1<<DIM];
+			Node<T>[] na = Refs.newArray(Node.class, 1<<DIM);
 			CBIterator<NodeEntry<T>> it = ind.iterator();
 			while (it.hasNext()) {
 				Entry<NodeEntry<T>> e = it.nextEntry();
@@ -830,7 +830,7 @@ T niDeconstruct(int DIM, long posToRemove, boolean removeSub) {
 			setSubHC( false );
 			int bia2Size = calcArraySizeTotalBits(newPostCnt, DIM);
 			long[] bia2 = Bits.arrayCreate(bia2Size);
-			Node<T>[] sa2 = new Node[newSubCnt];
+			Node<T>[] sa2 = Refs.newArray(Node.class, newSubCnt);
 			int preSubBits = getBitPos_SubNodeIndex(DIM);
 			//Copy only bits that are relevant. Otherwise we might mess up the not-null table!
 			Bits.copyBitsLeft(ba, 0, bia2, 0, preSubBits);
@@ -954,10 +954,12 @@ T getPostPOB(int offsPostKey, long pos, long[] key) {
 
 	/**
 	 * Get post-fix.
-	 * @param offsPostKey
-	 * @param key
-	 * @param range After the method call, this contains the postfix if the postfix matches the
-	 * range. Otherwise it contains only part of the postfix.
+	 * @param offsPostKey offsPostKey
+	 * @param hcPos hcPos
+	 * @param key key
+	 * @param rangeMin After the method call, this contains the postfix if the postfix matches
+	 *                 the range. Otherwise it contains only part of the postfix.
+	 * @param rangeMax rangeMax
 	 * @return NodeEntry if the postfix matches the range, otherwise null.
 	 * @Deprecated Use next method instead.
 	 */
@@ -985,10 +987,12 @@ NodeEntry<T> getPostPOB(int offsPostKey, long hcPos, long[] key,
 
 	/**
 	 * Get post-fix.
-	 * @param offsPostKey
-	 * @param key
-	 * @param range After the method call, this contains the postfix if the postfix matches the
+	 * @param offsPostKey offsPostKey
+	 * @param hcPos hcPos
+	 * @param e entry
+	 * @param rangeMin After the method call, this contains the postfix if the postfix matches the
 	 * range. Otherwise it contains only part of the postfix.
+	 * @param rangeMax rangeMax
 	 * @return NodeEntry if the postfix matches the range, otherwise null.
 	 */
 	boolean getPostPOB(int offsPostKey, long hcPos, PhEntry<T> e, 
@@ -1042,12 +1046,18 @@ NodeEntry<T> getPostPOB_E(int offsPostKey, long hcPos, long[] key) {
 
 	/**
 	 * Get post-fix.
-	 * @param offsPostKey
-	 * @param key
-	 * @param range After the method call, this contains the postfix if the postfix matches the
-	 * range. Otherwise it contains only part of the postfix.
+	 * @param offsPostKey offsPostKey
+	 * @param hcPos hcPos
+	 * @param DIM dim
+	 * @param valTemplate valTemplate
+	 * @param rangeMin After the method call, this contains the postfix if the postfix matches
+	 *                 the range. Otherwise it contains only part of the postfix.
+	 * @param rangeMax rangeMax
+	 * @param minToCheck minToCheck
+	 * @param maxToCheck maxToCheck
 	 * @return true, if the postfix matches the range.
 	 */
+	@SuppressWarnings("unchecked")
 	PhEntry<T> getPostPOB(int offsPostKey, long hcPos, int DIM, long[] valTemplate,
 			long[] rangeMin, long[] rangeMax, int[] minToCheck, int[] maxToCheck) {
 		if (DEBUG && ind != null) {
@@ -1120,6 +1130,7 @@ PhEntry<T> getPostPOB(int offsPostKey, long hcPos, int DIM, long[] valTemplate,
 	/**
 	 * Same as above, but without checks.
 	 */
+	@SuppressWarnings("unchecked")
 	PhEntry<T> getPostPOBNoCheck(int offsPostKey, long hcPos, int DIM, long[] valTemplate,
 			long[] rangeMin, long[] rangeMax) {
 		if (DEBUG && ind != null) {
@@ -1209,6 +1220,7 @@ T getPost(long pos, long[] key) {
 	}
 
 
+	@SuppressWarnings("deprecated")
 	T removePostPOB(long pos, int offsPostKey, final int DIM) {
 		final int bufPostCnt = getPostCount();
 		final int bufSubCnt = getSubCount();
@@ -1428,14 +1440,6 @@ int getBitPos_Infix() {
 		return HC_BITS;//   +   DIM+1   +   DIM+1;
 	}
 
-	/**
-	 * 
-	 * @param offs
-	 * @param pos
-	 * @param DIM
-	 * @param bufSubCnt use -1 to have it calculated by this method
-	 * @return
-	 */
 	private int offs2ValPos(int offs, long pos, int DIM) {
 		if (isPostHC()) {
 			return (int) pos;
@@ -1451,8 +1455,8 @@ private int offs2ValPos(int offs, long pos, int DIM) {
 
 	/**
 	 * 
-	 * @param pos
-	 * @param DIM
+	 * @param pos position
+	 * @param DIM dim
 	 * @return 		The position (in bits) of the postfix VALUE. For LHC, the key is stored 
 	 * 				directly before the value.
 	 */
diff --git a/src/main/java/ch/ethz/globis/phtree/v8/NodeIteratorListReuse.java b/src/main/java/ch/ethz/globis/phtree/v8/NodeIteratorListReuse.java
index 2381a72..88f13f1 100644
--- a/src/main/java/ch/ethz/globis/phtree/v8/NodeIteratorListReuse.java
+++ b/src/main/java/ch/ethz/globis/phtree/v8/NodeIteratorListReuse.java
@@ -8,6 +8,7 @@
 
 import java.util.ArrayList;
 
+import ch.ethz.globis.phtree.util.Refs;
 import org.zoodb.index.critbit.CritBit64.Entry;
 import org.zoodb.index.critbit.CritBit64.QueryIteratorMask;
 
@@ -34,7 +35,8 @@ public class NodeIteratorListReuse<T, R> {
 	
 	public class PhIteratorStack {
 		@SuppressWarnings("unchecked")
-		private final NodeIterator[] stack = new NodeIteratorListReuse.NodeIterator[64];
+		private final NodeIterator[] stack =
+				Refs.newArray(NodeIteratorListReuse.NodeIterator.class, 64);
 		private int size = 0;
 
 
@@ -94,14 +96,9 @@ private final class NodeIterator {
 
 		/**
 		 * 
-		 * @param node
-		 * @param DIM
-		 * @param valTemplate A null indicates that no values are to be extracted.
+		 * @param node node
 		 * @param lower The minimum HC-Pos that a value should have.
-		 * @param upper
-		 * @param minValue The minimum value that any found value should have. If the found value is
-		 *  lower, the search continues.
-		 * @param maxValue
+		 * @param upper The maximum HC-Pos that a value should have.
 		 */
 		void reinitAndRun(Node<T> node, long lower, long upper) {
 			this.node = node;
diff --git a/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorFullNoGC.java b/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorFullNoGC.java
index 65cf0a6..0d471fc 100644
--- a/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorFullNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorFullNoGC.java
@@ -12,6 +12,7 @@
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTreeHelper;
 import ch.ethz.globis.phtree.PhTree.PhExtent;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * This PhIterator uses a loop instead of recursion in findNextElement();. 
@@ -33,7 +34,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack() {
-			stack = new NodeIteratorFullNoGC[PhTree8.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorFullNoGC.class, PhTree8.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorNoGC.java b/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorNoGC.java
index f1a81ca..abc0ad0 100644
--- a/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorNoGC.java
+++ b/src/main/java/ch/ethz/globis/phtree/v8/PhIteratorNoGC.java
@@ -12,6 +12,7 @@
 import ch.ethz.globis.phtree.PhFilter;
 import ch.ethz.globis.phtree.PhTreeHelper;
 import ch.ethz.globis.phtree.PhTree.PhQuery;
+import ch.ethz.globis.phtree.util.Refs;
 
 /**
  * This PhIterator uses a loop instead of recursion in findNextElement();. 
@@ -33,7 +34,7 @@ private class PhIteratorStack {
 		
 		@SuppressWarnings("unchecked")
 		public PhIteratorStack() {
-			stack = new NodeIteratorNoGC[PhTree8.DEPTH_64];
+			stack = Refs.newArray(NodeIteratorNoGC.class, PhTree8.DEPTH_64);
 		}
 
 		public boolean isEmpty() {
diff --git a/src/main/java/ch/ethz/globis/phtree/v8/PhTree8.java b/src/main/java/ch/ethz/globis/phtree/v8/PhTree8.java
index 21f48ce..3065dc0 100644
--- a/src/main/java/ch/ethz/globis/phtree/v8/PhTree8.java
+++ b/src/main/java/ch/ethz/globis/phtree/v8/PhTree8.java
@@ -155,6 +155,9 @@ public int size() {
 
 	@Override
 	public PhTreeStats getStats() {
+		if (getRoot() == null) {
+			return new PhTreeStats(DEPTH_64);
+		}
 		return getQuality(0, getRoot(), new PhTreeStats(DEPTH_64));
 	}
 
diff --git a/src/main/java/org/zoodb/index/critbit/CritBit.java b/src/main/java/org/zoodb/index/critbit/CritBit.java
index 988316a..5db58cf 100644
--- a/src/main/java/org/zoodb/index/critbit/CritBit.java
+++ b/src/main/java/org/zoodb/index/critbit/CritBit.java
@@ -19,54 +19,54 @@
 
 /**
  * CritBit is a multi-dimensional OR arbitrary length crit-bit tree.
- * 
+ * <p>
  * Cribit trees are very space efficient due to prefix-sharing and suitable for
  * multi-dimensional data with low dimensionality (e.g. less than 10 dimensions or so).
  * They are also stable, that means unlike kD-trees or quadtrees they do not require
  * rebalancing, this makes update performance much more predictable.
- * 
+ * <p>
  * There is 1 1D-version and a kD-version (kD: k-dimensional).
  * The 1D version supports keys with arbitrary length (e.g. 256bit), the kD-version
  * supports k-dimensional keys with a maximum length of 64 bit per dimension. 
- * 
+ * <p>
  * Both tree versions use internally the same methods, except for the range queries.
  * For range queries, the 1D version interprets the parameters as one minimum and one
  * maximum value. For kD queries, the parameters are interpreted as arrays of
  * minimum and maximum values (i.e. the low left and upper right 
  * corner of a query (hyper-)rectangle). 
- * 
+ * <p>
  * All method ending with 'KD' are for k-dimensional use of the tree, all other methods are for
  * 1-dimensional use. Exceptions are the size(), printTree() and similar methods, which work  for
  * all dimensions. 
- * 
+ * <p>
  * In order to store floating point values, please convert them to 'long' with
  * BitTools.toSortableLong(...), also when supplying query parameters.
  * Extracted values can be converted back with BitTools.toDouble() or toFloat().
- * 
+ * <p>
  * Version 1.3.5 
  * - Fixed rare problem with postfix creation. This solves a problem
  *   with kd-queries and slightly reduces memory consumption.
- * 
+ * <p>
  * Version 1.3.2
  * - Added QueryIterator.reset()
- * 
+ * <p>
  * Version 1.3.1
  * - Fixed issue #3 where iterators won't work with 'null' as values.
- * 
+ * <p>
  * Version 1.2.2  
  *  - Moved tests to tst folder
- *
+ * <p>
  * Version 1.2.1  
  *  - Replaced compare() with isEqual() where possible
  *  - Simplified compare(), doesInfixMatch()
  *  - Removed unused arguments
- * 
+ * <p>
  * Version 1.2  
  *  - Added iterator() to iterate over all entries
- * 
+ * <p>
  * Version 1.1  
  *  - Slight performance improvements in mergeLong() and  readAndSplit()
- * 
+ * <p>
  * Version 1.0  
  *  - Initial release
  * 
@@ -136,7 +136,7 @@ public static <V> CritBit1D<V> create1D(int width) {
 			throw new IllegalArgumentException("Illegal bit width: " + width);
 		}
 		// SINGLE_DIM ensures that DIM is never used in this case.
-		return new CritBit<V>(width, SINGLE_DIM);
+		return new CritBit<>(width, SINGLE_DIM);
 	}
 	
 	/**
@@ -154,7 +154,7 @@ public static <V> CritBitKD<V> createKD(int width, int dim) {
 		if (dim < 1) {
 			throw new IllegalArgumentException("Illegal dimension count: " + dim);
 		}
-		return new CritBit<V>(width, dim);
+		return new CritBit<>(width, dim);
 	}
 	
 	/**
@@ -200,7 +200,7 @@ private V putNoCheck(long[] key, V val) {
 				if (posDiff < n.posDiff && posDiff != -1) {
 					long[] subInfix = extractInfix(currentPrefix, posDiff+1, n.posDiff-1);
 					//new sub-node
-					Node<V> newSub = new Node<V>(posDiff+1, n.loPost, n.loVal, n.hiPost, n.hiVal, 
+					Node<V> newSub = new Node<>(posDiff+1, n.loPost, n.loVal, n.hiPost, n.hiVal,
 							subInfix, n.posDiff);
 					newSub.hi = n.hi;
 					newSub.lo = n.lo;
@@ -365,8 +365,8 @@ private boolean checkNode(Node<V> n, int firstBitOfNode) {
 	
 	/**
 	 * Creates a postfix starting at posDiff+1.
-	 * @param val
-	 * @param posDiff
+	 * @param val val
+	 * @param posDiff posDiff
 	 * @return the postfix.
 	 */
 	private long[] createPostFix(long[] val, int posDiff) {
@@ -391,9 +391,9 @@ private Node<V> createNode(long[] k1, V val1, long[] k2, V val2, int posFirstBit
 		long[] p2 = createPostFix(k2, posDiff);
 		//if (isABitwiseSmallerB(v1, v2)) {
 		if (BitTools.getBit(k2, posDiff)) {
-			return new Node<V>(posFirstBit, p1, val1, p2, val2, infix, posDiff);
+			return new Node<>(posFirstBit, p1, val1, p2, val2, infix, posDiff);
 		} else {
-			return new Node<V>(posFirstBit, p2, val2, p1, val1, infix, posDiff);
+			return new Node<>(posFirstBit, p2, val2, p1, val1, infix, posDiff);
 		}
 	}
 	
@@ -439,9 +439,9 @@ private static long[] extractInfix(long[] v, int startPos, int endPos) {
 	}
 
 	/**
-	 * 
+	 * @param n node
 	 * @param v key 
-	 * @param startPos start position
+	 * @param currentVal currentVal
 	 * @return True if the infix matches the value or if no infix is defined
 	 */
 	private boolean doesInfixMatch(Node<V> n, long[] v, long[] currentVal) {
@@ -736,7 +736,7 @@ private void updateParentAfterRemove(Node<V> parent, long[] newPost, V newVal,
 	@Override
 	public FullIterator<V> iterator() {
 		checkDim0(); 
-		return new FullIterator<V>(this, DEPTH);
+		return new FullIterator<>(this, DEPTH);
 	}
 	
 	public static class FullIterator<V> implements Iterator<V> {
@@ -752,10 +752,10 @@ public static class FullIterator<V> implements Iterator<V> {
 		private int stackTop = -1;
 
 		@SuppressWarnings("unchecked")
-		public FullIterator(CritBit<V> cb, int DEPTH) {
-			this.stack = new Node[DEPTH];
-			this.readHigherNext = new byte[DEPTH];  // default = false
-			int intArrayLen = (DEPTH+63) >>> 6;
+		public FullIterator(CritBit<V> cb, int depth) {
+			this.stack = (Node[]) new Object[depth];
+			this.readHigherNext = new byte[depth];  // default = false
+			int intArrayLen = (depth+63) >>> 6;
 			this.valIntTemplate = new long[intArrayLen];
 
 			if (cb.rootKey != null) {
@@ -821,8 +821,8 @@ private void findNext() {
 		/**
 		 * Full comparison on the parameter. Assigns the parameter to 'nextVal' if comparison
 		 * fits.
-		 * @param keyTemplate
-		 * @param value
+		 * @param keyTemplate keyTemplate
+		 * @param value value
 		 */
 		private void readNextVal(long[] keyTemplate, V value) {
 			nextValue = value;
@@ -857,7 +857,7 @@ public Entry<V> nextEntry() {
 			if (!hasNext()) {
 				throw new NoSuchElementException();
 			}
-			Entry<V> ret = new Entry<V>(nextKey, nextValue);
+			Entry<V> ret = new Entry<>(nextKey, nextValue);
 			findNext();
 			return ret;
 		}
@@ -872,7 +872,7 @@ public void remove() {
 	@Override
 	public QueryIterator<V> query(long[] min, long[] max) {
 		checkDim0(); 
-		return new QueryIterator<V>(this, min, max);
+		return new QueryIterator<>(this, min, max);
 	}
 	
 	public static class QueryIterator<V> implements Iterator<V> {
@@ -889,12 +889,13 @@ public static class QueryIterator<V> implements Iterator<V> {
 		private static final byte RETURN_TO_PARENT = 2;
 		private final byte[] readHigherNext;
 		private int stackTop = -1;
-		private final boolean[] loEnclosed, hiEnclosed;
+		private final boolean[] loEnclosed;
+		private final boolean[] hiEnclosed;
 
 		@SuppressWarnings("unchecked")
 		QueryIterator(CritBit<V> cb, long[] minOrig, long[] maxOrig) {
 			this.cb = cb;
-			this.stack = new Node[cb.DEPTH];
+			this.stack = (Node[]) new Object[cb.DEPTH];
 			this.readHigherNext = new byte[cb.DEPTH];  // default = false
 			int intArrayLen = (cb.DEPTH+63) >>> 6;
 			this.valIntTemplate = new long[intArrayLen];
@@ -981,7 +982,7 @@ private void findNext() {
 
 		/**
 		 * Comparison on the post-fix. Assigns the parameter to 'nextVal' if comparison fits.
-		 * @param keyTemplate
+		 * @param keyTemplate keyTemplate
 		 * @return Whether we have a match or not
 		 */
 		private boolean checkMatchIntoNextVal(long[] keyTemplate, int startBit, V value) {
@@ -1094,7 +1095,7 @@ public Entry<V> nextEntry() {
 			if (!hasNext()) {
 				throw new NoSuchElementException();
 			}
-			Entry<V> ret = new Entry<V>(nextKey, nextValue);
+			Entry<V> ret = new Entry<>(nextKey, nextValue);
 			findNext();
 			return ret;
 		}
@@ -1127,15 +1128,15 @@ public static class QueryIteratorWithMask<V> implements Iterator<V> {
 		private final long MAX_MASK;
 
 		@SuppressWarnings("unchecked")
-		public QueryIteratorWithMask(CritBit<V> cb, long[] minOrig, long[] maxOrig, int DIM) {
+		public QueryIteratorWithMask(CritBit<V> cb, long[] minOrig, long[] maxOrig, int dim) {
 			this.cb = cb;
-			this.stack = new Node[cb.DEPTH];
+			this.stack = (Node[]) new Object[cb.DEPTH];
 			this.readHigherNext = new byte[cb.DEPTH];  // default = false
 			int intArrayLen = (cb.DEPTH+63) >>> 6;
 			this.valIntTemplate = new long[intArrayLen];
 			this.domMaskLo = new long[intArrayLen];
 			this.domMaskHi = new long[intArrayLen];
-			this.MAX_MASK = ~((-1L) << DIM);
+			this.MAX_MASK = ~((-1L) << dim);
 			reset(minOrig, maxOrig);
 		}
 
@@ -1222,7 +1223,7 @@ private void findNext() {
 
 		/**
 		 * Comparison on the post-fix. Assigns the parameter to 'nextVal' if comparison fits.
-		 * @param keyTemplate
+		 * @param keyTemplate keyTemplate
 		 * @return Whether we have a match or not
 		 */
 		private boolean checkMatchIntoNextVal(long[] keyTemplate, int startBit, V value) {
@@ -1449,7 +1450,7 @@ public Entry<V> nextEntry() {
 			if (!hasNext()) {
 				throw new NoSuchElementException();
 			}
-			Entry<V> ret = new Entry<V>(nextKey, nextValue);
+			Entry<V> ret = new Entry<>(nextKey, nextValue);
 			findNext();
 			return ret;
 		}
@@ -1488,7 +1489,7 @@ public static class CheckEmptyWithMask {
 		 */
 		public CheckEmptyWithMask(CritBit<?> cb, int dims) {
 			this.cb = cb;
-			this.stack = new Node[cb.DEPTH];
+			this.stack = (Node[]) new Object[cb.DEPTH];
 			this.readHigherNext = new byte[cb.DEPTH];  // default = false
 			int intArrayLen = (cb.DEPTH+63) >>> 6;
 			this.valIntTemplate = new long[intArrayLen];
@@ -1585,7 +1586,7 @@ private boolean findNext() {
 
 		/**
 		 * Comparison on the post-fix. Assigns the parameter to 'nextVal' if comparison fits.
-		 * @param keyTemplate
+		 * @param keyTemplate keyTemplate
 		 * @return Whether we have a match or not
 		 */
 		private boolean checkMatchIntoNextVal(long[] keyTemplate, int startBit) {
@@ -1885,7 +1886,7 @@ private void checkDIM(long[] key) {
 	public QueryIteratorKD<V> queryKD(long[] min, long[] max) {
 		checkDIM(min);
 		checkDIM(max);
-		return new QueryIteratorKD<V>(this, min, max, DIM, DEPTH);
+		return new QueryIteratorKD<>(this, min, max, DIM, DEPTH);
 	}
 	
 	public static class QueryIteratorKD<V> implements Iterator<V> {
@@ -1908,16 +1909,16 @@ public static class QueryIteratorKD<V> implements Iterator<V> {
 		private int stackTop = -1;
 
 		@SuppressWarnings("unchecked")
-		public QueryIteratorKD(CritBit<V> cb, long[] minOrig, long[] maxOrig, int DIM, int DEPTH) {
-			this.stack = new Node[DIM*DEPTH];
-			this.readHigherNext = new byte[DIM*DEPTH];  // default = false
-			this.keyOrigTemplate = new long[DIM];
+		public QueryIteratorKD(CritBit<V> cb, long[] minOrig, long[] maxOrig, int dim, int depth) {
+			this.stack = (Node[]) new Object[dim*depth];
+			this.readHigherNext = new byte[dim*depth];  // default = false
+			this.keyOrigTemplate = new long[dim];
 			this.minOrig = minOrig;
 			this.maxOrig = maxOrig;
-			this.DIM = DIM;
-			this.DIM_INV_16 = 1 + ((1<<16)+1)/DIM;
-			this.DEPTH = DEPTH;
-			this.DEPTH_OFFS = 64-DEPTH;  //the shift local to any Long
+			this.DIM = dim;
+			this.DIM_INV_16 = 1 + ((1<<16)+1)/dim;
+			this.DEPTH = depth;
+			this.DEPTH_OFFS = 64-depth;  //the shift local to any Long
 
 			if (cb.rootKey != null) {
 				readPostFixAndSplit(cb.rootKey, 0, keyOrigTemplate);
@@ -2003,7 +2004,7 @@ private void unsetBitAfterSplit(long[] keyOrigTemplate, int posBitInt) {
 		/**
 		 * Full comparison on the parameter. Assigns the parameter to 'nextKey' if comparison
 		 * fits.
-		 * @param keyTemplate
+		 * @param keyOrigTemplate keyOrigTemplate
 		 * @return Whether we have a match or not
 		 */
 		private boolean checkMatchOrigKDFullIntoNextVal(long[] keyOrigTemplate, V value) {
@@ -2075,9 +2076,8 @@ private boolean checkMatchOrigKD(long[] keyOrigTemplate, int currentDepth) {
 		
 		/**
 		 * 
-		 * @param n
-		 * @param infixStart The bit-position of the first infix bits relative to the whole value
-		 * @param currentPrefix
+		 * @param n node
+		 * @param currentPrefixOrig currentPrefixOrig
 		 */
 		private <T> void readAndSplitInfix(Node<T> n, long[] currentPrefixOrig) {
 			if (n.infix == null) {
@@ -2092,11 +2092,11 @@ private void readPostFixAndSplit(long[] postVal, int posFirstBit, long[] current
 		}
 		
 		/**
-		 * 
-		 * @param src Interleaved src array
+		 * QUESTIONS: TZ: hack: I fixed the javadoc errors without checking if the javadoc is correct!
+		 * @param srcVal Interleaved(?) src array
 		 * @param posFirstBit First bit to be transferred
 		 * @param stopBit Stop bit (last bit to be transferred + 1)
-		 * @param dst Non-interleaved destination array
+		 * @param dstVal Non-interleaved(?) destination array
 		 */
 		private void readAndSplit(long[] srcVal, int posFirstBit, long stopBit, long[] dstVal) {
 			long maskSrc = 0x8000000000000000L >>> (posFirstBit & 0x3F);
@@ -2126,7 +2126,7 @@ private void readAndSplit(long[] srcVal, int posFirstBit, long stopBit, long[] d
 		/**
 		 * Calculate the common minimum depth across all dimensions.
 		 * This is equal to {@code floor(posDirstBit/DIM)}.
-		 * @param posFirstBit
+		 * @param posFirstBit posFirstBit
 		 * @return depth across dims.
 		 */
 		private int getDepthAcrossDims(int posFirstBit) {
@@ -2162,7 +2162,7 @@ public Entry<V> nextEntry() {
 			if (!hasNext()) {
 				throw new NoSuchElementException();
 			}
-			Entry<V> ret = new Entry<V>(nextKey, nextValue);
+			Entry<V> ret = new Entry<>(nextKey, nextValue);
 			findNext();
 			return ret;
 		}
diff --git a/src/main/java/org/zoodb/index/critbit/CritBit64.java b/src/main/java/org/zoodb/index/critbit/CritBit64.java
index d38488c..f0b4f25 100644
--- a/src/main/java/org/zoodb/index/critbit/CritBit64.java
+++ b/src/main/java/org/zoodb/index/critbit/CritBit64.java
@@ -55,6 +55,8 @@
  * 
  * @author Tilmann Zaeschke
  */
+import ch.ethz.globis.phtree.util.Refs;
+
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 
@@ -331,9 +333,9 @@ private static long extractPrefix(long v, int endPos) {
 	}
 
 	/**
-	 * 
+	 * @param posDiff posDIff
 	 * @param v key
-	 * @param startPos start position
+	 * @param prefix prefix
 	 * @return True if the prefix matches the value or if no prefix is defined
 	 */
 	private boolean doesPrefixMatch(int posDiff, long v, long prefix) {
@@ -533,7 +535,7 @@ public static class CBIterator<V> implements Iterator<V> {
 
 		@SuppressWarnings("unchecked")
 		public CBIterator() {
-			this.stack = new Node[DEPTH];
+			this.stack = Refs.newArray(Node.class, DEPTH);
 			this.readHigherNext = new byte[DEPTH];  // default = false
 		}
 		
@@ -664,7 +666,7 @@ public static class QueryIterator<V> implements Iterator<V> {
 
 		@SuppressWarnings("unchecked")
 		public QueryIterator() {
-			this.stack = new Node[DEPTH];
+			this.stack = (Node[]) new Object[DEPTH];
 			this.readHigherNext = new byte[DEPTH];  // default = false
 			this.prefixes = new long[DEPTH];
 		}
@@ -844,7 +846,7 @@ public static class QueryIteratorMask<V> implements Iterator<V> {
 
 		@SuppressWarnings("unchecked")
 		public QueryIteratorMask() {
-			this.stack = new Node[DEPTH];
+			this.stack = Refs.newArray(Node.class, DEPTH);
 			this.readHigherNext = new byte[DEPTH];  // default = false
 			this.prefixes = new long[DEPTH];
 		}
diff --git a/src/test/java/ch/ethz/globis/phtree/bits/TestBitsByte.java b/src/test/java/ch/ethz/globis/phtree/bits/TestBitsByte.java
index 0aa3f8d..1745447 100644
--- a/src/test/java/ch/ethz/globis/phtree/bits/TestBitsByte.java
+++ b/src/test/java/ch/ethz/globis/phtree/bits/TestBitsByte.java
@@ -350,7 +350,7 @@ private void checkBinarySearch(byte[] ba, int key) {
 	private void check(byte[] t, long ... ints) {
 		for (int i = 0; i < ints.length; i++) {
 			assertEquals("i=" + i + " " + Bits.toBinary(ints, 8) + " / " + 
-					BitsByte.toBinary(t), (byte)ints[i], (byte)t[i]);
+					BitsByte.toBinary(t), (byte)ints[i], t[i]);
 		}
 	}
 
diff --git a/src/test/java/ch/ethz/globis/phtree/bits/TestBitsShort.java b/src/test/java/ch/ethz/globis/phtree/bits/TestBitsShort.java
index 2349f3b..5afa9ca 100644
--- a/src/test/java/ch/ethz/globis/phtree/bits/TestBitsShort.java
+++ b/src/test/java/ch/ethz/globis/phtree/bits/TestBitsShort.java
@@ -430,14 +430,14 @@ private void checkBinarySearch(short[] ba, int key) {
 	private void check(short[] t, long ... ints) {
 		for (int i = 0; i < ints.length; i++) {
 			assertEquals("i=" + i + " | " + BitsShort.toBinary(ints, 16) + " / " + 
-					BitsShort.toBinary(t), (short)ints[i], (short)t[i]);
+					BitsShort.toBinary(t), (short)ints[i], t[i]);
 		}
 	}
 
 	private void check(short[] t, short[] s) {
 		for (int i = 0; i < s.length; i++) {
 			assertEquals("i=" + i + " | " + BitsShort.toBinary(s) + " / " + 
-					BitsShort.toBinary(t), (short)s[i], (short)t[i]);
+					BitsShort.toBinary(t), s[i], t[i]);
 		}
 	}
 
diff --git a/src/test/java/ch/ethz/globis/phtree/bst/TestNT.java b/src/test/java/ch/ethz/globis/phtree/bst/TestNT.java
index 3bdc52e..849d118 100644
--- a/src/test/java/ch/ethz/globis/phtree/bst/TestNT.java
+++ b/src/test/java/ch/ethz/globis/phtree/bst/TestNT.java
@@ -36,7 +36,7 @@ public void testBSTree() {
 		//lookup
 		for (int i = 0; i < N; i++) {
 			int x = ht.get(i, out);
-			assertEquals("i=" + i, i+100, (int) x);
+			assertEquals("i=" + i, i+100, x);
 			//if (i%1000 == 0) System.out.println("lu=" + i);
 		}
 		
diff --git a/src/test/java/ch/ethz/globis/phtree/test/util/TestUtil.java b/src/test/java/ch/ethz/globis/phtree/test/util/TestUtil.java
index 0d0c7a1..9d43284 100644
--- a/src/test/java/ch/ethz/globis/phtree/test/util/TestUtil.java
+++ b/src/test/java/ch/ethz/globis/phtree/test/util/TestUtil.java
@@ -69,16 +69,13 @@ public static void beforeTest(Object[] args) {
 	
 	/**
 	 * Do we need this?
-	 * @deprecated do not use
 	 */
 	public static void afterTest() {
 		getInstance().afterTest();
 	}
 
-	
 	/**
 	 * Do we need this?
-	 * @deprecated do not use
 	 */
 	public static void beforeClass() {
 		getInstance().beforeClass();
@@ -86,16 +83,13 @@ public static void beforeClass() {
 
 	/**
 	 * Do we need this?
-	 * @deprecated do not use
 	 */
 	public static void afterClass() {
 		getInstance().afterClass();
 	}
 
-	
 	/**
 	 * Do we need this?
-	 * @deprecated do not use
 	 */
 	public static void beforeSuite() {
 		getInstance().beforeSuite();