diff --git a/src/main/java/com/clearspring/analytics/stream/cardinality/CountThenEstimate.java b/src/main/java/com/clearspring/analytics/stream/cardinality/CountThenEstimate.java
index 32ff84c3e..e1dd7d179 100644
--- a/src/main/java/com/clearspring/analytics/stream/cardinality/CountThenEstimate.java
+++ b/src/main/java/com/clearspring/analytics/stream/cardinality/CountThenEstimate.java
@@ -183,7 +183,7 @@ public boolean tipped()
     }
 
     @Override
-    public byte[] getBytes() throws IOException
+    public byte[] getBytes()
     {
         return ExternalizableUtil.toBytes(this);
     }
diff --git a/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLog.java b/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLog.java
index 588aad749..8f17d9a5e 100644
--- a/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLog.java
+++ b/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLog.java
@@ -16,17 +16,13 @@
 
 package com.clearspring.analytics.stream.cardinality;
 
+import java.io.Serializable;
+import java.nio.ByteBuffer;
+
 import com.clearspring.analytics.hash.MurmurHash;
 import com.clearspring.analytics.util.Bits;
 import com.clearspring.analytics.util.IBuilder;
 
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.io.Serializable;
-
 /**
  * Java implementation of HyperLogLog (HLL) algorithm from this paper:
  * <p/>
@@ -215,20 +211,17 @@ public int sizeof()
         return registerSet.size * 4;
     }
 
-    @Override
-    public byte[] getBytes() throws IOException
-    {
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        DataOutputStream dos = new DataOutputStream(baos);
 
-        dos.writeInt(log2m);
-        dos.writeInt(registerSet.size * 4);
+    @Override
+    public byte[] getBytes() {
+        ByteBuffer bb = ByteBuffer.allocate(Bits.INT_BYTES * (1+1+registerSet.size));
+        bb.putInt(log2m);
+        bb.putInt(registerSet.size * Bits.INT_BYTES);
         for (int x : registerSet.bits())
         {
-            dos.writeInt(x);
+            bb.putInt(x);
         }
-
-        return baos.toByteArray();
+        return bb.array();
     }
 
     @Override
@@ -283,15 +276,13 @@ public int sizeof()
             return RegisterSet.getBits(k) * 4;
         }
 
-        public static HyperLogLog build(byte[] bytes) throws IOException
+        public static HyperLogLog build(byte[] bytes)
         {
-            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
-            DataInputStream oi = new DataInputStream(bais);
-            int log2m = oi.readInt();
-            int size = oi.readInt();
-            byte[] longArrayBytes = new byte[size];
-            oi.readFully(longArrayBytes);
-            return new HyperLogLog(log2m, new RegisterSet((int) Math.pow(2, log2m), Bits.getBits(longArrayBytes)));
+            ByteBuffer bb = ByteBuffer.wrap(bytes);
+            int log2m = bb.getInt();
+            int size = bb.getInt();
+            int [] regSetDump = Bits.getBits(bb, size);
+            return new HyperLogLog(log2m, new RegisterSet((int) Math.pow(2, log2m), regSetDump));
         }
     }
 
diff --git a/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLogPlus.java b/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLogPlus.java
index 51de1a6de..fbbf21f12 100644
--- a/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLogPlus.java
+++ b/src/main/java/com/clearspring/analytics/stream/cardinality/HyperLogLogPlus.java
@@ -22,6 +22,7 @@
 import com.clearspring.analytics.util.Varint;
 
 import java.io.*;
+import java.nio.ByteBuffer;
 import java.util.*;
 
 
@@ -820,36 +821,47 @@ public int sizeof()
     }
 
     @Override
-    public byte[] getBytes() throws IOException
+    public byte[] getBytes()
     {
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        DataOutputStream dos = new DataOutputStream(baos);
-
-        dos.writeInt(p);
-        dos.writeInt(sp);
+        ByteBuffer bb = null;
+        
         switch (format)
         {
             case NORMAL:
-                dos.writeInt(0);
-                dos.writeInt(registerSet.size * 4);
+                int bbSize = Bits.INT_BYTES * (1+1+1+1+registerSet.size);
+                bb = ByteBuffer.allocate(bbSize);
+                bb.putInt(p);
+                bb.putInt(sp);
+                bb.putInt(0);
+                bb.putInt((Integer.SIZE/8) * registerSet.size);
                 for (int x : registerSet.bits())
                 {
-                    dos.writeInt(x);
+                    bb.putInt(x);
                 }
                 break;
             case SPARSE:
-                dos.writeInt(1);
                 mergeTempList();
+
+                int sparseByteCount = 0;
+                for (byte[] bytes: sparseSet)
+                {
+                    sparseByteCount += Bits.INT_BYTES * 1 + bytes.length;
+                }
+
+                bb = ByteBuffer.allocate(Bits.INT_BYTES * (1+1+1+1) + sparseByteCount);
+                bb.putInt(p);
+                bb.putInt(sp);
+                bb.putInt(1);
                 for (byte[] bytes : sparseSet)
                 {
-                    dos.writeInt(bytes.length);
-                    dos.write(bytes);
+                    bb.putInt(bytes.length);
+                    bb.put(bytes);
                 }
-                dos.writeInt(-1);
+                bb.putInt(-1);
                 break;
         }
 
-        return baos.toByteArray();
+        return bb.array();
     }
 
     /**
@@ -1009,19 +1021,18 @@ public int sizeof()
             return RegisterSet.getBits(k) * 5;
         }
 
-        public static HyperLogLogPlus build(byte[] bytes) throws IOException
+        public static HyperLogLogPlus build(byte[] bytes)
         {
-            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
-            DataInputStream oi = new DataInputStream(bais);
-            int p = oi.readInt();
-            int sp = oi.readInt();
-            int formatType = oi.readInt();
+            ByteBuffer bb = ByteBuffer.wrap(bytes);
+
+            int p = bb.getInt();
+            int sp = bb.getInt();
+            int formatType = bb.getInt();
             if (formatType == 0)
             {
-                int size = oi.readInt();
-                byte[] longArrayBytes = new byte[size];
-                oi.readFully(longArrayBytes);
-                HyperLogLogPlus hyperLogLogPlus = new HyperLogLogPlus(p, sp, new RegisterSet((int) Math.pow(2, p), Bits.getBits(longArrayBytes)));
+                int size = bb.getInt();
+                int [] regSetDump = Bits.getBits(bb, size);
+                HyperLogLogPlus hyperLogLogPlus = new HyperLogLogPlus(p, sp, new RegisterSet((int) Math.pow(2, p), regSetDump));
                 hyperLogLogPlus.format = Format.NORMAL;
                 return hyperLogLogPlus;
             }
@@ -1029,10 +1040,10 @@ public static HyperLogLogPlus build(byte[] bytes) throws IOException
             {
                 int l;
                 List<byte[]> rehydratedSet = new ArrayList<byte[]>();
-                while ((l = oi.readInt()) > 0)
+                while ((l = bb.getInt()) > 0)
                 {
                     byte[] longArrayBytes = new byte[l];
-                    oi.read(longArrayBytes, 0, l);
+                    bb.get(longArrayBytes, 0, l);
                     rehydratedSet.add(longArrayBytes);
                 }
                 HyperLogLogPlus hyperLogLogPlus = new HyperLogLogPlus(p, sp, rehydratedSet);
diff --git a/src/main/java/com/clearspring/analytics/stream/cardinality/ICardinality.java b/src/main/java/com/clearspring/analytics/stream/cardinality/ICardinality.java
index 111c4a91f..5cf5ff43b 100644
--- a/src/main/java/com/clearspring/analytics/stream/cardinality/ICardinality.java
+++ b/src/main/java/com/clearspring/analytics/stream/cardinality/ICardinality.java
@@ -57,7 +57,7 @@ public interface ICardinality
      * @return
      * @throws IOException
      */
-    byte[] getBytes() throws IOException;
+    byte[] getBytes();
 
     /**
      * Merges estimators to produce an estimator for the combined streams
diff --git a/src/main/java/com/clearspring/analytics/util/Bits.java b/src/main/java/com/clearspring/analytics/util/Bits.java
index 10c029cbe..14cdc1d7c 100644
--- a/src/main/java/com/clearspring/analytics/util/Bits.java
+++ b/src/main/java/com/clearspring/analytics/util/Bits.java
@@ -16,21 +16,19 @@
 
 package com.clearspring.analytics.util;
 
-import java.io.ByteArrayInputStream;
-import java.io.DataInputStream;
-import java.io.IOException;
+import java.nio.ByteBuffer;
 
 public class Bits
 {
 
-    public static int[] getBits(byte[] mBytes) throws IOException
+    public static final int INT_BYTES = Integer.SIZE / 8;
+
+    public static int [] getBits(ByteBuffer bb, int size)
     {
-        int bitSize = mBytes.length / 4;
-        int[] bits = new int[bitSize];
-        DataInputStream dis = new DataInputStream(new ByteArrayInputStream(mBytes));
-        for (int i = 0; i < bitSize; i++)
-        {
-            bits[i] = dis.readInt();
+        int count = size / (Integer.SIZE/8);
+        int [] bits = new int[count];
+        for (int i = 0; i < count; i++) {
+            bits[i] = bb.getInt();
         }
         return bits;
     }
diff --git a/src/main/java/com/clearspring/analytics/util/ExternalizableUtil.java b/src/main/java/com/clearspring/analytics/util/ExternalizableUtil.java
index 33077ab4b..236b8d179 100644
--- a/src/main/java/com/clearspring/analytics/util/ExternalizableUtil.java
+++ b/src/main/java/com/clearspring/analytics/util/ExternalizableUtil.java
@@ -7,12 +7,17 @@
 
 public class ExternalizableUtil
 {
-    public static byte[] toBytes(Externalizable o) throws IOException
+    public static byte[] toBytes(Externalizable o)
     {
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        ObjectOutputStream out = new ObjectOutputStream(baos);
-        o.writeExternal(out);
-        out.flush();
-        return baos.toByteArray();
+        try {
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            ObjectOutputStream out = new ObjectOutputStream(baos);
+            o.writeExternal(out);
+            out.flush();
+            return baos.toByteArray();
+        } catch (IOException e) {
+            // ByteArrayOutputStream does not throw IOException
+            throw new IllegalStateException(e);
+        }
     }
 }