diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
index 476d51b..9aa39e0 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
@@ -162,15 +162,16 @@
      * Gets the address of the last CharGroup of the exact matching word in the dictionary.
      * If no match is found, returns NOT_VALID_WORD.
      *
-     * @param buffer the buffer to read.
+     * @param reader the reader.
      * @param word the word we search for.
      * @return the address of the terminal node.
      * @throws IOException if the file can't be read.
      * @throws UnsupportedFormatException if the format of the file is not recognized.
      */
     @UsedForTesting
-    public static int getTerminalPosition(final FusionDictionaryBufferInterface buffer,
+    public static int getTerminalPosition(final BinaryDictReader reader,
             final String word) throws IOException, UnsupportedFormatException {
+        final FusionDictionaryBufferInterface buffer = reader.getBuffer();
         if (word == null) return FormatSpec.NOT_VALID_WORD;
         if (buffer.position() != 0) buffer.position(0);
 
@@ -507,18 +508,19 @@
     }
 
     /**
-     * Find a word from the buffer.
+     * Find a word using the BinaryDictReader.
      *
-     * @param buffer the buffer representing the body of the dictionary file.
+     * @param reader the reader
      * @param word the word searched
      * @return the found group
      * @throws IOException
      * @throws UnsupportedFormatException
      */
     @UsedForTesting
-    public static CharGroupInfo findWordFromBuffer(final FusionDictionaryBufferInterface buffer,
+    public static CharGroupInfo findWordByBinaryDictReader(final BinaryDictReader reader,
             final String word) throws IOException, UnsupportedFormatException {
-        int position = getTerminalPosition(buffer, word);
+        int position = getTerminalPosition(reader, word);
+        final FusionDictionaryBufferInterface buffer = reader.getBuffer();
         if (position != FormatSpec.NOT_VALID_WORD) {
             buffer.position(0);
             final FileHeader header = BinaryDictDecoder.readHeader(buffer);
diff --git a/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
index 5d116d7..11f9f8a 100644
--- a/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
@@ -49,17 +49,18 @@
     /**
      * Delete the word from the binary file.
      *
-     * @param buffer the buffer to write.
+     * @param reader the reader.
      * @param word the word we delete
      * @throws IOException
      * @throws UnsupportedFormatException
      */
     @UsedForTesting
-    public static void deleteWord(final FusionDictionaryBufferInterface buffer,
-            final String word) throws IOException, UnsupportedFormatException {
+    public static void deleteWord(final BinaryDictReader reader, final String word)
+            throws IOException, UnsupportedFormatException {
+        final FusionDictionaryBufferInterface buffer = reader.getBuffer();
         buffer.position(0);
         final FileHeader header = BinaryDictDecoder.readHeader(buffer);
-        final int wordPosition = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+        final int wordPosition = BinaryDictIOUtils.getTerminalPosition(reader, word);
         if (wordPosition == FormatSpec.NOT_VALID_WORD) return;
 
         buffer.position(wordPosition);
@@ -235,7 +236,7 @@
     /**
      * Insert a word into a binary dictionary.
      *
-     * @param buffer the buffer containing the existing dictionary.
+     * @param reader the reader.
      * @param destination a stream to the underlying file, with the pointer at the end of the file.
      * @param word the word to insert.
      * @param frequency the frequency of the new word.
@@ -248,16 +249,16 @@
     // TODO: Support batch insertion.
     // TODO: Remove @UsedForTesting once UserHistoryDictionary is implemented by BinaryDictionary.
     @UsedForTesting
-    public static void insertWord(final FusionDictionaryBufferInterface buffer,
-            final OutputStream destination, final String word, final int frequency,
-            final ArrayList<WeightedString> bigramStrings,
+    public static void insertWord(final BinaryDictReader reader, final OutputStream destination,
+            final String word, final int frequency, final ArrayList<WeightedString> bigramStrings,
             final ArrayList<WeightedString> shortcuts, final boolean isNotAWord,
             final boolean isBlackListEntry)
                     throws IOException, UnsupportedFormatException {
         final ArrayList<PendingAttribute> bigrams = new ArrayList<PendingAttribute>();
+        final FusionDictionaryBufferInterface buffer = reader.getBuffer();
         if (bigramStrings != null) {
             for (final WeightedString bigram : bigramStrings) {
-                int position = BinaryDictIOUtils.getTerminalPosition(buffer, bigram.mWord);
+                int position = BinaryDictIOUtils.getTerminalPosition(reader, bigram.mWord);
                 if (position == FormatSpec.NOT_VALID_WORD) {
                     // TODO: figure out what is the correct thing to do here.
                 } else {
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
index 6d37466..e98790b 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
@@ -493,8 +493,8 @@
     }
 
     // Tests for getTerminalPosition
-    private String getWordFromBinary(final FusionDictionaryBufferInterface buffer,
-            final int address) {
+    private String getWordFromBinary(final BinaryDictReader reader, final int address) {
+        final FusionDictionaryBufferInterface buffer = reader.getBuffer();
         if (buffer.position() != 0) buffer.position(0);
 
         FileHeader header = null;
@@ -510,14 +510,14 @@
                 address - header.mHeaderSize, header.mFormatOptions).mWord;
     }
 
-    private long runGetTerminalPosition(final FusionDictionaryBufferInterface buffer,
-            final String word, int index, boolean contained) {
+    private long runGetTerminalPosition(final BinaryDictReader reader, final String word, int index,
+            boolean contained) {
         final int expectedFrequency = (UNIGRAM_FREQ + index) % 255;
         long diff = -1;
         int position = -1;
         try {
             final long now = System.nanoTime();
-            position = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+            position = BinaryDictIOUtils.getTerminalPosition(reader, word);
             diff = System.nanoTime() - now;
         } catch (IOException e) {
             Log.e(TAG, "IOException while getTerminalPosition", e);
@@ -526,7 +526,7 @@
         }
 
         assertEquals(FormatSpec.NOT_VALID_WORD != position, contained);
-        if (contained) assertEquals(getWordFromBinary(buffer, position), word);
+        if (contained) assertEquals(getWordFromBinary(reader, position), word);
         return diff;
     }
 
@@ -547,29 +547,27 @@
         timeWritingDictToFile(file, dict, VERSION3_WITH_DYNAMIC_UPDATE);
 
         final BinaryDictReader reader = new BinaryDictReader(file);
-        FusionDictionaryBufferInterface buffer = null;
         try {
-            buffer = reader.openAndGetBuffer(
-                    new BinaryDictReader.FusionDictionaryBufferFromByteArrayFactory());
+            reader.openBuffer(new BinaryDictReader.FusionDictionaryBufferFromByteArrayFactory());
         } catch (IOException e) {
             // ignore
             Log.e(TAG, "IOException while opening the buffer", e);
         }
-        assertNotNull("Can't get the buffer", buffer);
+        assertNotNull("Can't get the buffer", reader.getBuffer());
 
         try {
             // too long word
             final String longWord = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, longWord));
+                    BinaryDictIOUtils.getTerminalPosition(reader, longWord));
 
             // null
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, null));
+                    BinaryDictIOUtils.getTerminalPosition(reader, null));
 
             // empty string
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, ""));
+                    BinaryDictIOUtils.getTerminalPosition(reader, ""));
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
         }
@@ -577,7 +575,7 @@
         // Test a word that is contained within the dictionary.
         long sum = 0;
         for (int i = 0; i < sWords.size(); ++i) {
-            final long time = runGetTerminalPosition(buffer, sWords.get(i), i, true);
+            final long time = runGetTerminalPosition(reader, sWords.get(i), i, true);
             sum += time == -1 ? 0 : time;
         }
         Log.d(TAG, "per a search : " + (((double)sum) / sWords.size() / 1000000));
@@ -588,7 +586,7 @@
         for (int i = 0; i < 1000; ++i) {
             final String word = generateWord(random, codePointSet);
             if (sWords.indexOf(word) != -1) continue;
-            runGetTerminalPosition(buffer, word, i, false);
+            runGetTerminalPosition(reader, word, i, false);
         }
     }
 
@@ -608,28 +606,27 @@
         timeWritingDictToFile(file, dict, VERSION3_WITH_DYNAMIC_UPDATE);
 
         final BinaryDictReader reader = new BinaryDictReader(file);
-        FusionDictionaryBufferInterface buffer = null;
         try {
-            buffer = reader.openAndGetBuffer(
+            reader.openBuffer(
                     new BinaryDictReader.FusionDictionaryBufferFromByteArrayFactory());
         } catch (IOException e) {
             // ignore
             Log.e(TAG, "IOException while opening the buffer", e);
         }
-        assertNotNull("Can't get the buffer", buffer);
+        assertNotNull("Can't get the buffer", reader.getBuffer());
 
         try {
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(0)));
-            DynamicBinaryDictIOUtils.deleteWord(buffer, sWords.get(0));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(0)));
+            DynamicBinaryDictIOUtils.deleteWord(reader, sWords.get(0));
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(0)));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(0)));
 
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(5)));
-            DynamicBinaryDictIOUtils.deleteWord(buffer, sWords.get(5));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(5)));
+            DynamicBinaryDictIOUtils.deleteWord(reader, sWords.get(5));
             assertEquals(FormatSpec.NOT_VALID_WORD,
-                    BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(5)));
+                    BinaryDictIOUtils.getTerminalPosition(reader, sWords.get(5)));
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
         }
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
index 011d711..300fd6a 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
@@ -21,8 +21,9 @@
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
 
-import com.android.inputmethod.latin.makedict.BinaryDictDecoder.ByteBufferWrapper;
 import com.android.inputmethod.latin.makedict.BinaryDictDecoder.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.BinaryDictReader.
+        FusionDictionaryBufferFromWritableByteBufferFactory;
 import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
 import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
@@ -33,8 +34,6 @@
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.io.RandomAccessFile;
-import java.nio.channels.FileChannel;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Random;
@@ -137,12 +136,12 @@
 
     private int getWordPosition(final File file, final String word) {
         int position = FormatSpec.NOT_VALID_WORD;
+        final BinaryDictReader reader = new BinaryDictReader(file);
         FileInputStream inStream = null;
         try {
             inStream = new FileInputStream(file);
-            final FusionDictionaryBufferInterface buffer = new ByteBufferWrapper(
-                    inStream.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length()));
-            position = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+            reader.openBuffer(new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
+            position = BinaryDictIOUtils.getTerminalPosition(reader, word);
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
         } finally {
@@ -158,23 +157,13 @@
     }
 
     private CharGroupInfo findWordFromFile(final File file, final String word) {
-        FileInputStream inStream = null;
+        final BinaryDictReader reader = new BinaryDictReader(file);
         CharGroupInfo info = null;
         try {
-            inStream = new FileInputStream(file);
-            final FusionDictionaryBufferInterface buffer = new ByteBufferWrapper(
-                    inStream.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length()));
-            info = BinaryDictIOUtils.findWordFromBuffer(buffer, word);
+            reader.openBuffer(new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
+            info = BinaryDictIOUtils.findWordByBinaryDictReader(reader, word);
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
-        } finally {
-            if (inStream != null) {
-                try {
-                    inStream.close();
-                } catch (IOException e) {
-                    // do nothing
-                }
-            }
         }
         return info;
     }
@@ -183,42 +172,33 @@
     private long insertAndCheckWord(final File file, final String word, final int frequency,
             final boolean exist, final ArrayList<WeightedString> bigrams,
             final ArrayList<WeightedString> shortcuts) {
-        RandomAccessFile raFile = null;
+        final BinaryDictReader reader = new BinaryDictReader(file);
         BufferedOutputStream outStream = null;
-        FusionDictionaryBufferInterface buffer = null;
         long amountOfTime = -1;
         try {
-            raFile = new RandomAccessFile(file, "rw");
-            buffer = new ByteBufferWrapper(raFile.getChannel().map(
-                    FileChannel.MapMode.READ_WRITE, 0, file.length()));
+            reader.openBuffer(new FusionDictionaryBufferFromWritableByteBufferFactory());
             outStream = new BufferedOutputStream(new FileOutputStream(file, true));
 
             if (!exist) {
                 assertEquals(FormatSpec.NOT_VALID_WORD, getWordPosition(file, word));
             }
             final long now = System.nanoTime();
-            DynamicBinaryDictIOUtils.insertWord(buffer, outStream, word, frequency, bigrams,
+            DynamicBinaryDictIOUtils.insertWord(reader, outStream, word, frequency, bigrams,
                     shortcuts, false, false);
             amountOfTime = System.nanoTime() - now;
             outStream.flush();
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD, getWordPosition(file, word));
             outStream.close();
-            raFile.close();
         } catch (IOException e) {
+            Log.e(TAG, "Raised an IOException while inserting a word", e);
         } catch (UnsupportedFormatException e) {
+            Log.e(TAG, "Raised an UnsupportedFormatException error while inserting a word", e);
         } finally {
             if (outStream != null) {
                 try {
                     outStream.close();
                 } catch (IOException e) {
-                    // do nothing
-                }
-            }
-            if (raFile != null) {
-                try {
-                    raFile.close();
-                } catch (IOException e) {
-                    // do nothing
+                    Log.e(TAG, "Failed to close the output stream", e);
                 }
             }
         }
@@ -226,45 +206,28 @@
     }
 
     private void deleteWord(final File file, final String word) {
-        RandomAccessFile raFile = null;
-        FusionDictionaryBufferInterface buffer = null;
+        final BinaryDictReader reader = new BinaryDictReader(file);
         try {
-            raFile = new RandomAccessFile(file, "rw");
-            buffer = new ByteBufferWrapper(raFile.getChannel().map(
-                    FileChannel.MapMode.READ_WRITE, 0, file.length()));
-            DynamicBinaryDictIOUtils.deleteWord(buffer, word);
+            reader.openBuffer(new FusionDictionaryBufferFromWritableByteBufferFactory());
+            DynamicBinaryDictIOUtils.deleteWord(reader, word);
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
-        } finally {
-            if (raFile != null) {
-                try {
-                    raFile.close();
-                } catch (IOException e) {
-                    // do nothing
-                }
-            }
         }
     }
 
     private void checkReverseLookup(final File file, final String word, final int position) {
-        FileInputStream inStream = null;
+        final BinaryDictReader reader = new BinaryDictReader(file);
         try {
-            inStream = new FileInputStream(file);
-            final FusionDictionaryBufferInterface buffer = new ByteBufferWrapper(
-                    inStream.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, file.length()));
+            final FusionDictionaryBufferInterface buffer = reader.openAndGetBuffer(
+                    new BinaryDictReader.FusionDictionaryBufferFromByteBufferFactory());
             final FileHeader header = BinaryDictDecoder.readHeader(buffer);
-            assertEquals(word, BinaryDictDecoder.getWordAtAddress(buffer, header.mHeaderSize,
-                    position - header.mHeaderSize, header.mFormatOptions).mWord);
+            assertEquals(word,
+                    BinaryDictDecoder.getWordAtAddress(reader.getBuffer(), header.mHeaderSize,
+                            position - header.mHeaderSize, header.mFormatOptions).mWord);
         } catch (IOException e) {
+            Log.e(TAG, "Raised an IOException while looking up a word", e);
         } catch (UnsupportedFormatException e) {
-        } finally {
-            if (inStream != null) {
-                try {
-                    inStream.close();
-                } catch (IOException e) {
-                    // do nothing
-                }
-            }
+            Log.e(TAG, "Raised an UnsupportedFormatException error while looking up a word", e);
         }
     }