diff --git a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
index 7c7064e..877fff2 100644
--- a/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
+++ b/java/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtils.java
@@ -32,14 +32,12 @@
 import java.io.OutputStream;
 import java.nio.channels.FileChannel;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Stack;
 
 public final class BinaryDictIOUtils {
     private static final boolean DBG = false;
-    private static final int MAX_JUMPS = 10000;
 
     private BinaryDictIOUtils() {
         // This utility class is not publicly instantiable.
@@ -246,36 +244,10 @@
         return FormatSpec.NOT_VALID_WORD;
     }
 
-    private static int markAsDeleted(final int flags) {
-        return (flags & (~FormatSpec.MASK_GROUP_ADDRESS_TYPE)) | FormatSpec.FLAG_IS_DELETED;
-    }
-
-    /**
-     * Delete the word from the binary file.
-     *
-     * @param buffer the buffer to write.
-     * @param word the word we delete
-     * @throws IOException
-     * @throws UnsupportedFormatException
-     */
-    @UsedForTesting
-    public static void deleteWord(final FusionDictionaryBufferInterface buffer,
-            final String word) throws IOException, UnsupportedFormatException {
-        buffer.position(0);
-        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
-        final int wordPosition = getTerminalPosition(buffer, word);
-        if (wordPosition == FormatSpec.NOT_VALID_WORD) return;
-
-        buffer.position(wordPosition);
-        final int flags = buffer.readUnsignedByte();
-        buffer.position(wordPosition);
-        buffer.put((byte)markAsDeleted(flags));
-    }
-
     /**
      * @return the size written, in bytes. Always 3 bytes.
      */
-    private static int writeSInt24ToBuffer(final FusionDictionaryBufferInterface buffer,
+    static int writeSInt24ToBuffer(final FusionDictionaryBufferInterface buffer,
             final int value) {
         final int absValue = Math.abs(value);
         buffer.put((byte)(((value < 0 ? 0x80 : 0) | (absValue >> 16)) & 0xFF));
@@ -287,7 +259,7 @@
     /**
      * @return the size written, in bytes. Always 3 bytes.
      */
-    private static int writeSInt24ToStream(final OutputStream destination, final int value)
+    static int writeSInt24ToStream(final OutputStream destination, final int value)
             throws IOException {
         final int absValue = Math.abs(value);
         destination.write((byte)(((value < 0 ? 0x80 : 0) | (absValue >> 16)) & 0xFF));
@@ -318,39 +290,7 @@
         return BinaryDictInputOutput.getByteSize(value);
     }
 
-    /**
-     * Update a parent address in a CharGroup that is referred to by groupOriginAddress.
-     *
-     * @param buffer the buffer to write.
-     * @param groupOriginAddress the address of the group.
-     * @param newParentAddress the absolute address of the parent.
-     * @param formatOptions file format options.
-     */
-    public static void updateParentAddress(final FusionDictionaryBufferInterface buffer,
-            final int groupOriginAddress, final int newParentAddress,
-            final FormatOptions formatOptions) {
-        final int originalPosition = buffer.position();
-        buffer.position(groupOriginAddress);
-        if (!formatOptions.mSupportsDynamicUpdate) {
-            throw new RuntimeException("this file format does not support parent addresses");
-        }
-        final int flags = buffer.readUnsignedByte();
-        if (BinaryDictInputOutput.isMovedGroup(flags, formatOptions)) {
-            // if the group is moved, the parent address is stored in the destination group.
-            // We are guaranteed to process the destination group later, so there is no need to
-            // update anything here.
-            buffer.position(originalPosition);
-            return;
-        }
-        if (DBG) {
-            MakedictLog.d("update parent address flags=" + flags + ", " + groupOriginAddress);
-        }
-        final int parentOffset = newParentAddress - groupOriginAddress;
-        writeSInt24ToBuffer(buffer, parentOffset);
-        buffer.position(originalPosition);
-    }
-
-    private static void skipCharGroup(final FusionDictionaryBufferInterface buffer,
+    static void skipCharGroup(final FusionDictionaryBufferInterface buffer,
             final FormatOptions formatOptions) {
         final int flags = buffer.readUnsignedByte();
         BinaryDictInputOutput.readParentAddress(buffer, formatOptions);
@@ -385,33 +325,7 @@
         }
     }
 
-    /**
-     * Update parent addresses in a Node that is referred to by nodeOriginAddress.
-     *
-     * @param buffer the buffer to be modified.
-     * @param nodeOriginAddress the address of a modified Node.
-     * @param newParentAddress the address to be written.
-     * @param formatOptions file format options.
-     */
-    public static void updateParentAddresses(final FusionDictionaryBufferInterface buffer,
-            final int nodeOriginAddress, final int newParentAddress,
-            final FormatOptions formatOptions) {
-        final int originalPosition = buffer.position();
-        buffer.position(nodeOriginAddress);
-        do {
-            final int count = BinaryDictInputOutput.readCharGroupCount(buffer);
-            for (int i = 0; i < count; ++i) {
-                updateParentAddress(buffer, buffer.position(), newParentAddress, formatOptions);
-                skipCharGroup(buffer, formatOptions);
-            }
-            final int forwardLinkAddress = buffer.readUnsignedInt24();
-            buffer.position(forwardLinkAddress);
-        } while (formatOptions.mSupportsDynamicUpdate
-                && buffer.position() != FormatSpec.NO_FORWARD_LINK_ADDRESS);
-        buffer.position(originalPosition);
-    }
-
-    private static void skipString(final FusionDictionaryBufferInterface buffer,
+    static void skipString(final FusionDictionaryBufferInterface buffer,
             final boolean hasMultipleChars) {
         if (hasMultipleChars) {
             int character = CharEncoding.readChar(buffer);
@@ -453,29 +367,6 @@
     }
 
     /**
-     * Update a children address in a CharGroup that is addressed by groupOriginAddress.
-     *
-     * @param buffer the buffer to write.
-     * @param groupOriginAddress the address of the group.
-     * @param newChildrenAddress the absolute address of the child.
-     * @param formatOptions file format options.
-     */
-    public static void updateChildrenAddress(final FusionDictionaryBufferInterface buffer,
-            final int groupOriginAddress, final int newChildrenAddress,
-            final FormatOptions formatOptions) {
-        final int originalPosition = buffer.position();
-        buffer.position(groupOriginAddress);
-        final int flags = buffer.readUnsignedByte();
-        final int parentAddress = BinaryDictInputOutput.readParentAddress(buffer, formatOptions);
-        skipString(buffer, (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS) != 0);
-        if ((flags & FormatSpec.FLAG_IS_TERMINAL) != 0) buffer.readUnsignedByte();
-        final int childrenOffset = newChildrenAddress == FormatSpec.NO_CHILDREN_ADDRESS
-                ? FormatSpec.NO_CHILDREN_ADDRESS : newChildrenAddress - buffer.position();
-        writeSInt24ToBuffer(buffer, childrenOffset);
-        buffer.position(originalPosition);
-    }
-
-    /**
      * Write a char group to an output stream.
      * A char group is an in-memory representation of a node in trie.
      * A char group info is an on-disk representation of a node.
@@ -567,52 +458,10 @@
         return size;
     }
 
-    @SuppressWarnings("unused")
-    private static void updateForwardLink(final FusionDictionaryBufferInterface buffer,
-            final int nodeOriginAddress, final int newNodeAddress,
-            final FormatOptions formatOptions) {
-        buffer.position(nodeOriginAddress);
-        int jumpCount = 0;
-        while (jumpCount++ < MAX_JUMPS) {
-            final int count = BinaryDictInputOutput.readCharGroupCount(buffer);
-            for (int i = 0; i < count; ++i) skipCharGroup(buffer, formatOptions);
-            final int forwardLinkAddress = buffer.readUnsignedInt24();
-            if (forwardLinkAddress == FormatSpec.NO_FORWARD_LINK_ADDRESS) {
-                buffer.position(buffer.position() - FormatSpec.FORWARD_LINK_ADDRESS_SIZE);
-                writeSInt24ToBuffer(buffer, newNodeAddress);
-                return;
-            }
-            buffer.position(forwardLinkAddress);
-        }
-        if (DBG && jumpCount >= MAX_JUMPS) {
-            throw new RuntimeException("too many jumps, probably a bug.");
-        }
-    }
-
-    /**
-     * Helper method to move a char group to the tail of the file.
-     */
-    private static int moveCharGroup(final OutputStream destination,
-            final FusionDictionaryBufferInterface buffer, final CharGroupInfo info,
-            final int nodeOriginAddress, final int oldGroupAddress,
-            final FormatOptions formatOptions) throws IOException {
-        updateParentAddress(buffer, oldGroupAddress, buffer.limit() + 1, formatOptions);
-        buffer.position(oldGroupAddress);
-        final int currentFlags = buffer.readUnsignedByte();
-        buffer.position(oldGroupAddress);
-        buffer.put((byte)(FormatSpec.FLAG_IS_MOVED | (currentFlags
-                & (~FormatSpec.MASK_MOVE_AND_DELETE_FLAG))));
-        int size = FormatSpec.GROUP_FLAGS_SIZE;
-        updateForwardLink(buffer, nodeOriginAddress, buffer.limit(), formatOptions);
-        size += writeNode(destination, new CharGroupInfo[] { info });
-        return size;
-    }
-
     /**
      * Compute the size of the char group.
      */
-    private static int computeGroupSize(final CharGroupInfo info,
-            final FormatOptions formatOptions) {
+    static int computeGroupSize(final CharGroupInfo info, final FormatOptions formatOptions) {
         int size = FormatSpec.GROUP_FLAGS_SIZE + FormatSpec.PARENT_ADDRESS_SIZE
                 + BinaryDictInputOutput.getGroupCharactersSize(info.mCharacters)
                 + BinaryDictInputOutput.getChildrenAddressSize(info.mFlags, formatOptions);
@@ -639,7 +488,7 @@
      * @return the size written, in bytes.
      * @throws IOException
      */
-    private static int writeNode(final OutputStream destination, final CharGroupInfo[] infos)
+    static int writeNode(final OutputStream destination, final CharGroupInfo[] infos)
             throws IOException {
         int size = BinaryDictInputOutput.getGroupCountSize(infos.length);
         switch (BinaryDictInputOutput.getGroupCountSize(infos.length)) {
@@ -659,306 +508,6 @@
     }
 
     /**
-     * Move a group that is referred to by oldGroupOrigin to the tail of the file.
-     * And set the children address to the byte after the group.
-     *
-     * @param nodeOrigin the address of the tail of the file.
-     * @param characters
-     * @param length
-     * @param flags
-     * @param frequency
-     * @param parentAddress
-     * @param shortcutTargets
-     * @param bigrams
-     * @param destination the stream representing the tail of the file.
-     * @param buffer the buffer representing the (constant-size) body of the file.
-     * @param oldNodeOrigin
-     * @param oldGroupOrigin
-     * @param formatOptions
-     * @return the size written, in bytes.
-     * @throws IOException
-     */
-    private static int moveGroup(final int nodeOrigin, final int[] characters, final int length,
-            final int flags, final int frequency, final int parentAddress,
-            final ArrayList<WeightedString> shortcutTargets,
-            final ArrayList<PendingAttribute> bigrams, final OutputStream destination,
-            final FusionDictionaryBufferInterface buffer, final int oldNodeOrigin,
-            final int oldGroupOrigin, final FormatOptions formatOptions) throws IOException {
-        int size = 0;
-        final int newGroupOrigin = nodeOrigin + 1;
-        final int[] writtenCharacters = Arrays.copyOfRange(characters, 0, length);
-        final CharGroupInfo tmpInfo = new CharGroupInfo(newGroupOrigin, -1 /* endAddress */,
-                flags, writtenCharacters, frequency, parentAddress, FormatSpec.NO_CHILDREN_ADDRESS,
-                shortcutTargets, bigrams);
-        size = computeGroupSize(tmpInfo, formatOptions);
-        final CharGroupInfo newInfo = new CharGroupInfo(newGroupOrigin, newGroupOrigin + size,
-                flags, writtenCharacters, frequency, parentAddress,
-                nodeOrigin + 1 + size + FormatSpec.FORWARD_LINK_ADDRESS_SIZE, shortcutTargets,
-                bigrams);
-        moveCharGroup(destination, buffer, newInfo, oldNodeOrigin, oldGroupOrigin, formatOptions);
-        return 1 + size + FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
-    }
-
-    /**
-     * Insert a word into a binary dictionary.
-     *
-     * @param buffer
-     * @param destination
-     * @param word
-     * @param frequency
-     * @param bigramStrings
-     * @param shortcuts
-     * @throws IOException
-     * @throws UnsupportedFormatException
-     */
-    // 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,
-            final ArrayList<WeightedString> shortcuts, final boolean isNotAWord,
-            final boolean isBlackListEntry)
-                    throws IOException, UnsupportedFormatException {
-        final ArrayList<PendingAttribute> bigrams = new ArrayList<PendingAttribute>();
-        if (bigramStrings != null) {
-            for (final WeightedString bigram : bigramStrings) {
-                int position = getTerminalPosition(buffer, bigram.mWord);
-                if (position == FormatSpec.NOT_VALID_WORD) {
-                    // TODO: figure out what is the correct thing to do here.
-                } else {
-                    bigrams.add(new PendingAttribute(bigram.mFrequency, position));
-                }
-            }
-        }
-
-        final boolean isTerminal = true;
-        final boolean hasBigrams = !bigrams.isEmpty();
-        final boolean hasShortcuts = shortcuts != null && !shortcuts.isEmpty();
-
-        // find the insert position of the word.
-        if (buffer.position() != 0) buffer.position(0);
-        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
-
-        int wordPos = 0, address = buffer.position(), nodeOriginAddress = buffer.position();
-        final int[] codePoints = FusionDictionary.getCodePoints(word);
-        final int wordLen = codePoints.length;
-
-        for (int depth = 0; depth < Constants.DICTIONARY_MAX_WORD_LENGTH; ++depth) {
-            if (wordPos >= wordLen) break;
-            nodeOriginAddress = buffer.position();
-            int nodeParentAddress = -1;
-            final int charGroupCount = BinaryDictInputOutput.readCharGroupCount(buffer);
-            boolean foundNextGroup = false;
-
-            for (int i = 0; i < charGroupCount; ++i) {
-                address = buffer.position();
-                final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
-                        buffer.position(), header.mFormatOptions);
-                final boolean isMovedGroup = BinaryDictInputOutput.isMovedGroup(currentInfo.mFlags,
-                        header.mFormatOptions);
-                if (isMovedGroup) continue;
-                nodeParentAddress = (currentInfo.mParentAddress == FormatSpec.NO_PARENT_ADDRESS)
-                        ? FormatSpec.NO_PARENT_ADDRESS : currentInfo.mParentAddress + address;
-                boolean matched = true;
-                for (int p = 0; p < currentInfo.mCharacters.length; ++p) {
-                    if (wordPos + p >= wordLen) {
-                        /*
-                         * splitting
-                         * before
-                         *  abcd - ef
-                         *
-                         * insert "abc"
-                         *
-                         * after
-                         *  abc - d - ef
-                         */
-                        final int newNodeAddress = buffer.limit();
-                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(p > 1,
-                                isTerminal, 0, hasShortcuts, hasBigrams, false /* isNotAWord */,
-                                false /* isBlackListEntry */, header.mFormatOptions);
-                        int written = moveGroup(newNodeAddress, currentInfo.mCharacters, p, flags,
-                                frequency, nodeParentAddress, shortcuts, bigrams, destination,
-                                buffer, nodeOriginAddress, address, header.mFormatOptions);
-
-                        final int[] characters2 = Arrays.copyOfRange(currentInfo.mCharacters, p,
-                                currentInfo.mCharacters.length);
-                        if (currentInfo.mChildrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
-                            updateParentAddresses(buffer, currentInfo.mChildrenAddress,
-                                    newNodeAddress + written + 1, header.mFormatOptions);
-                        }
-                        final CharGroupInfo newInfo2 = new CharGroupInfo(
-                                newNodeAddress + written + 1, -1 /* endAddress */,
-                                currentInfo.mFlags, characters2, currentInfo.mFrequency,
-                                newNodeAddress + 1, currentInfo.mChildrenAddress,
-                                currentInfo.mShortcutTargets, currentInfo.mBigrams);
-                        writeNode(destination, new CharGroupInfo[] { newInfo2 });
-                        return;
-                    } else if (codePoints[wordPos + p] != currentInfo.mCharacters[p]) {
-                        if (p > 0) {
-                            /*
-                             * splitting
-                             * before
-                             *   ab - cd
-                             *
-                             * insert "ac"
-                             *
-                             * after
-                             *   a - b - cd
-                             *     |
-                             *     - c
-                             */
-
-                            final int newNodeAddress = buffer.limit();
-                            final int childrenAddress = currentInfo.mChildrenAddress;
-
-                            // move prefix
-                            final int prefixFlags = BinaryDictInputOutput.makeCharGroupFlags(p > 1,
-                                    false /* isTerminal */, 0 /* childrenAddressSize*/,
-                                    false /* hasShortcut */, false /* hasBigrams */,
-                                    false /* isNotAWord */, false /* isBlackListEntry */,
-                                    header.mFormatOptions);
-                            int written = moveGroup(newNodeAddress, currentInfo.mCharacters, p,
-                                    prefixFlags, -1 /* frequency */, nodeParentAddress, null, null,
-                                    destination, buffer, nodeOriginAddress, address,
-                                    header.mFormatOptions);
-
-                            final int[] suffixCharacters = Arrays.copyOfRange(
-                                    currentInfo.mCharacters, p, currentInfo.mCharacters.length);
-                            if (currentInfo.mChildrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
-                                updateParentAddresses(buffer, currentInfo.mChildrenAddress,
-                                        newNodeAddress + written + 1, header.mFormatOptions);
-                            }
-                            final int suffixFlags = BinaryDictInputOutput.makeCharGroupFlags(
-                                    suffixCharacters.length > 1,
-                                    (currentInfo.mFlags & FormatSpec.FLAG_IS_TERMINAL) != 0,
-                                    0 /* childrenAddressSize */,
-                                    (currentInfo.mFlags & FormatSpec.FLAG_HAS_SHORTCUT_TARGETS)
-                                            != 0,
-                                    (currentInfo.mFlags & FormatSpec.FLAG_HAS_BIGRAMS) != 0,
-                                    isNotAWord, isBlackListEntry, header.mFormatOptions);
-                            final CharGroupInfo suffixInfo = new CharGroupInfo(
-                                    newNodeAddress + written + 1, -1 /* endAddress */, suffixFlags,
-                                    suffixCharacters, currentInfo.mFrequency, newNodeAddress + 1,
-                                    currentInfo.mChildrenAddress, currentInfo.mShortcutTargets,
-                                    currentInfo.mBigrams);
-                            written += computeGroupSize(suffixInfo, header.mFormatOptions) + 1;
-
-                            final int[] newCharacters = Arrays.copyOfRange(codePoints, wordPos + p,
-                                    codePoints.length);
-                            final int flags = BinaryDictInputOutput.makeCharGroupFlags(
-                                    newCharacters.length > 1, isTerminal,
-                                    0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                                    isNotAWord, isBlackListEntry, header.mFormatOptions);
-                            final CharGroupInfo newInfo = new CharGroupInfo(
-                                    newNodeAddress + written, -1 /* endAddress */, flags,
-                                    newCharacters, frequency, newNodeAddress + 1,
-                                    FormatSpec.NO_CHILDREN_ADDRESS, shortcuts, bigrams);
-                            writeNode(destination, new CharGroupInfo[] { suffixInfo, newInfo });
-                            return;
-                        }
-                        matched = false;
-                        break;
-                    }
-                }
-
-                if (matched) {
-                    if (wordPos + currentInfo.mCharacters.length == wordLen) {
-                        // the word exists in the dictionary.
-                        // only update group.
-                        final int newNodeAddress = buffer.limit();
-                        final boolean hasMultipleChars = currentInfo.mCharacters.length > 1;
-                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(hasMultipleChars,
-                                isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                                isNotAWord, isBlackListEntry, header.mFormatOptions);
-                        final CharGroupInfo newInfo = new CharGroupInfo(newNodeAddress + 1,
-                                -1 /* endAddress */, flags, currentInfo.mCharacters, frequency,
-                                nodeParentAddress, currentInfo.mChildrenAddress, shortcuts,
-                                bigrams);
-                        moveCharGroup(destination, buffer, newInfo, nodeOriginAddress, address,
-                                header.mFormatOptions);
-                        return;
-                    }
-                    wordPos += currentInfo.mCharacters.length;
-                    if (currentInfo.mChildrenAddress == FormatSpec.NO_CHILDREN_ADDRESS) {
-                        /*
-                         * found the prefix of the word.
-                         * make new node and link to the node from this group.
-                         *
-                         * before
-                         * ab - cd
-                         *
-                         * insert "abcde"
-                         *
-                         * after
-                         * ab - cd - e
-                         */
-                        final int newNodeAddress = buffer.limit();
-                        updateChildrenAddress(buffer, address, newNodeAddress,
-                                header.mFormatOptions);
-                        final int newGroupAddress = newNodeAddress + 1;
-                        final boolean hasMultipleChars = (wordLen - wordPos) > 1;
-                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(hasMultipleChars,
-                                isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                                isNotAWord, isBlackListEntry, header.mFormatOptions);
-                        final int[] characters = Arrays.copyOfRange(codePoints, wordPos, wordLen);
-                        final CharGroupInfo newInfo = new CharGroupInfo(newGroupAddress, -1, flags,
-                                characters, frequency, address, FormatSpec.NO_CHILDREN_ADDRESS,
-                                shortcuts, bigrams);
-                        writeNode(destination, new CharGroupInfo[] { newInfo });
-                        return;
-                    }
-                    buffer.position(currentInfo.mChildrenAddress);
-                    foundNextGroup = true;
-                    break;
-                }
-            }
-
-            if (foundNextGroup) continue;
-
-            // reached the end of the array.
-            final int linkAddressPosition = buffer.position();
-            int nextLink = buffer.readUnsignedInt24();
-            if ((nextLink & FormatSpec.MSB24) != 0) {
-                nextLink = -(nextLink & FormatSpec.SINT24_MAX);
-            }
-            if (nextLink == FormatSpec.NO_FORWARD_LINK_ADDRESS) {
-                /*
-                 * expand this node.
-                 *
-                 * before
-                 * ab - cd
-                 *
-                 * insert "abef"
-                 *
-                 * after
-                 * ab - cd
-                 *    |
-                 *    - ef
-                 */
-
-                // change the forward link address.
-                final int newNodeAddress = buffer.limit();
-                buffer.position(linkAddressPosition);
-                writeSInt24ToBuffer(buffer, newNodeAddress);
-
-                final int[] characters = Arrays.copyOfRange(codePoints, wordPos, wordLen);
-                final int flags = BinaryDictInputOutput.makeCharGroupFlags(characters.length > 1,
-                        isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
-                        isNotAWord, isBlackListEntry, header.mFormatOptions);
-                final CharGroupInfo newInfo = new CharGroupInfo(newNodeAddress + 1,
-                        -1 /* endAddress */, flags, characters, frequency, nodeParentAddress,
-                        FormatSpec.NO_CHILDREN_ADDRESS, shortcuts, bigrams);
-                writeNode(destination, new CharGroupInfo[]{ newInfo });
-                return;
-            } else {
-                depth--;
-                buffer.position(nextLink);
-            }
-        }
-    }
-
-    /**
      * Find a word from the buffer.
      *
      * @param buffer the buffer representing the body of the dictionary file.
diff --git a/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
new file mode 100644
index 0000000..fd728f1
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/makedict/DynamicBinaryDictIOUtils.java
@@ -0,0 +1,493 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.inputmethod.latin.makedict;
+
+import com.android.inputmethod.annotations.UsedForTesting;
+import com.android.inputmethod.latin.Constants;
+import com.android.inputmethod.latin.makedict.BinaryDictInputOutput.FusionDictionaryBufferInterface;
+import com.android.inputmethod.latin.makedict.FormatSpec.FileHeader;
+import com.android.inputmethod.latin.makedict.FormatSpec.FormatOptions;
+import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+/**
+ * The utility class to help dynamic updates on the binary dictionary.
+ *
+ * All the methods in this class are static.
+ */
+@UsedForTesting
+public final class DynamicBinaryDictIOUtils {
+    private static final boolean DBG = false;
+    private static final int MAX_JUMPS = 10000;
+
+    private DynamicBinaryDictIOUtils() {
+        // This utility class is not publicly instantiable.
+    }
+
+    private static int markAsDeleted(final int flags) {
+        return (flags & (~FormatSpec.MASK_GROUP_ADDRESS_TYPE)) | FormatSpec.FLAG_IS_DELETED;
+    }
+
+    /**
+     * Delete the word from the binary file.
+     *
+     * @param buffer the buffer to write.
+     * @param word the word we delete
+     * @throws IOException
+     * @throws UnsupportedFormatException
+     */
+    @UsedForTesting
+    public static void deleteWord(final FusionDictionaryBufferInterface buffer,
+            final String word) throws IOException, UnsupportedFormatException {
+        buffer.position(0);
+        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
+        final int wordPosition = BinaryDictIOUtils.getTerminalPosition(buffer, word);
+        if (wordPosition == FormatSpec.NOT_VALID_WORD) return;
+
+        buffer.position(wordPosition);
+        final int flags = buffer.readUnsignedByte();
+        buffer.position(wordPosition);
+        buffer.put((byte)markAsDeleted(flags));
+    }
+
+    /**
+     * Update a parent address in a CharGroup that is referred to by groupOriginAddress.
+     *
+     * @param buffer the buffer to write.
+     * @param groupOriginAddress the address of the group.
+     * @param newParentAddress the absolute address of the parent.
+     * @param formatOptions file format options.
+     */
+    public static void updateParentAddress(final FusionDictionaryBufferInterface buffer,
+            final int groupOriginAddress, final int newParentAddress,
+            final FormatOptions formatOptions) {
+        final int originalPosition = buffer.position();
+        buffer.position(groupOriginAddress);
+        if (!formatOptions.mSupportsDynamicUpdate) {
+            throw new RuntimeException("this file format does not support parent addresses");
+        }
+        final int flags = buffer.readUnsignedByte();
+        if (BinaryDictInputOutput.isMovedGroup(flags, formatOptions)) {
+            // if the group is moved, the parent address is stored in the destination group.
+            // We are guaranteed to process the destination group later, so there is no need to
+            // update anything here.
+            buffer.position(originalPosition);
+            return;
+        }
+        if (DBG) {
+            MakedictLog.d("update parent address flags=" + flags + ", " + groupOriginAddress);
+        }
+        final int parentOffset = newParentAddress - groupOriginAddress;
+        BinaryDictIOUtils.writeSInt24ToBuffer(buffer, parentOffset);
+        buffer.position(originalPosition);
+    }
+
+    /**
+     * Update parent addresses in a Node that is referred to by nodeOriginAddress.
+     *
+     * @param buffer the buffer to be modified.
+     * @param nodeOriginAddress the address of a modified Node.
+     * @param newParentAddress the address to be written.
+     * @param formatOptions file format options.
+     */
+    public static void updateParentAddresses(final FusionDictionaryBufferInterface buffer,
+            final int nodeOriginAddress, final int newParentAddress,
+            final FormatOptions formatOptions) {
+        final int originalPosition = buffer.position();
+        buffer.position(nodeOriginAddress);
+        do {
+            final int count = BinaryDictInputOutput.readCharGroupCount(buffer);
+            for (int i = 0; i < count; ++i) {
+                updateParentAddress(buffer, buffer.position(), newParentAddress, formatOptions);
+                BinaryDictIOUtils.skipCharGroup(buffer, formatOptions);
+            }
+            final int forwardLinkAddress = buffer.readUnsignedInt24();
+            buffer.position(forwardLinkAddress);
+        } while (formatOptions.mSupportsDynamicUpdate
+                && buffer.position() != FormatSpec.NO_FORWARD_LINK_ADDRESS);
+        buffer.position(originalPosition);
+    }
+
+    /**
+     * Update a children address in a CharGroup that is addressed by groupOriginAddress.
+     *
+     * @param buffer the buffer to write.
+     * @param groupOriginAddress the address of the group.
+     * @param newChildrenAddress the absolute address of the child.
+     * @param formatOptions file format options.
+     */
+    public static void updateChildrenAddress(final FusionDictionaryBufferInterface buffer,
+            final int groupOriginAddress, final int newChildrenAddress,
+            final FormatOptions formatOptions) {
+        final int originalPosition = buffer.position();
+        buffer.position(groupOriginAddress);
+        final int flags = buffer.readUnsignedByte();
+        final int parentAddress = BinaryDictInputOutput.readParentAddress(buffer, formatOptions);
+        BinaryDictIOUtils.skipString(buffer, (flags & FormatSpec.FLAG_HAS_MULTIPLE_CHARS) != 0);
+        if ((flags & FormatSpec.FLAG_IS_TERMINAL) != 0) buffer.readUnsignedByte();
+        final int childrenOffset = newChildrenAddress == FormatSpec.NO_CHILDREN_ADDRESS
+                ? FormatSpec.NO_CHILDREN_ADDRESS : newChildrenAddress - buffer.position();
+        BinaryDictIOUtils.writeSInt24ToBuffer(buffer, childrenOffset);
+        buffer.position(originalPosition);
+    }
+
+    /**
+     * Helper method to move a char group to the tail of the file.
+     */
+    private static int moveCharGroup(final OutputStream destination,
+            final FusionDictionaryBufferInterface buffer, final CharGroupInfo info,
+            final int nodeOriginAddress, final int oldGroupAddress,
+            final FormatOptions formatOptions) throws IOException {
+        updateParentAddress(buffer, oldGroupAddress, buffer.limit() + 1, formatOptions);
+        buffer.position(oldGroupAddress);
+        final int currentFlags = buffer.readUnsignedByte();
+        buffer.position(oldGroupAddress);
+        buffer.put((byte)(FormatSpec.FLAG_IS_MOVED | (currentFlags
+                & (~FormatSpec.MASK_MOVE_AND_DELETE_FLAG))));
+        int size = FormatSpec.GROUP_FLAGS_SIZE;
+        updateForwardLink(buffer, nodeOriginAddress, buffer.limit(), formatOptions);
+        size += BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[] { info });
+        return size;
+    }
+    @SuppressWarnings("unused")
+    private static void updateForwardLink(final FusionDictionaryBufferInterface buffer,
+            final int nodeOriginAddress, final int newNodeAddress,
+            final FormatOptions formatOptions) {
+        buffer.position(nodeOriginAddress);
+        int jumpCount = 0;
+        while (jumpCount++ < MAX_JUMPS) {
+            final int count = BinaryDictInputOutput.readCharGroupCount(buffer);
+            for (int i = 0; i < count; ++i) BinaryDictIOUtils.skipCharGroup(buffer, formatOptions);
+            final int forwardLinkAddress = buffer.readUnsignedInt24();
+            if (forwardLinkAddress == FormatSpec.NO_FORWARD_LINK_ADDRESS) {
+                buffer.position(buffer.position() - FormatSpec.FORWARD_LINK_ADDRESS_SIZE);
+                BinaryDictIOUtils.writeSInt24ToBuffer(buffer, newNodeAddress);
+                return;
+            }
+            buffer.position(forwardLinkAddress);
+        }
+        if (DBG && jumpCount >= MAX_JUMPS) {
+            throw new RuntimeException("too many jumps, probably a bug.");
+        }
+    }
+
+    /**
+     * Move a group that is referred to by oldGroupOrigin to the tail of the file.
+     * And set the children address to the byte after the group.
+     *
+     * @param nodeOrigin the address of the tail of the file.
+     * @param characters
+     * @param length
+     * @param flags
+     * @param frequency
+     * @param parentAddress
+     * @param shortcutTargets
+     * @param bigrams
+     * @param destination the stream representing the tail of the file.
+     * @param buffer the buffer representing the (constant-size) body of the file.
+     * @param oldNodeOrigin
+     * @param oldGroupOrigin
+     * @param formatOptions
+     * @return the size written, in bytes.
+     * @throws IOException
+     */
+    private static int moveGroup(final int nodeOrigin, final int[] characters, final int length,
+            final int flags, final int frequency, final int parentAddress,
+            final ArrayList<WeightedString> shortcutTargets,
+            final ArrayList<PendingAttribute> bigrams, final OutputStream destination,
+            final FusionDictionaryBufferInterface buffer, final int oldNodeOrigin,
+            final int oldGroupOrigin, final FormatOptions formatOptions) throws IOException {
+        int size = 0;
+        final int newGroupOrigin = nodeOrigin + 1;
+        final int[] writtenCharacters = Arrays.copyOfRange(characters, 0, length);
+        final CharGroupInfo tmpInfo = new CharGroupInfo(newGroupOrigin, -1 /* endAddress */,
+                flags, writtenCharacters, frequency, parentAddress, FormatSpec.NO_CHILDREN_ADDRESS,
+                shortcutTargets, bigrams);
+        size = BinaryDictIOUtils.computeGroupSize(tmpInfo, formatOptions);
+        final CharGroupInfo newInfo = new CharGroupInfo(newGroupOrigin, newGroupOrigin + size,
+                flags, writtenCharacters, frequency, parentAddress,
+                nodeOrigin + 1 + size + FormatSpec.FORWARD_LINK_ADDRESS_SIZE, shortcutTargets,
+                bigrams);
+        moveCharGroup(destination, buffer, newInfo, oldNodeOrigin, oldGroupOrigin, formatOptions);
+        return 1 + size + FormatSpec.FORWARD_LINK_ADDRESS_SIZE;
+    }
+
+    /**
+     * Insert a word into a binary dictionary.
+     *
+     * @param buffer
+     * @param destination
+     * @param word
+     * @param frequency
+     * @param bigramStrings
+     * @param shortcuts
+     * @throws IOException
+     * @throws UnsupportedFormatException
+     */
+    // 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,
+            final ArrayList<WeightedString> shortcuts, final boolean isNotAWord,
+            final boolean isBlackListEntry)
+                    throws IOException, UnsupportedFormatException {
+        final ArrayList<PendingAttribute> bigrams = new ArrayList<PendingAttribute>();
+        if (bigramStrings != null) {
+            for (final WeightedString bigram : bigramStrings) {
+                int position = BinaryDictIOUtils.getTerminalPosition(buffer, bigram.mWord);
+                if (position == FormatSpec.NOT_VALID_WORD) {
+                    // TODO: figure out what is the correct thing to do here.
+                } else {
+                    bigrams.add(new PendingAttribute(bigram.mFrequency, position));
+                }
+            }
+        }
+
+        final boolean isTerminal = true;
+        final boolean hasBigrams = !bigrams.isEmpty();
+        final boolean hasShortcuts = shortcuts != null && !shortcuts.isEmpty();
+
+        // find the insert position of the word.
+        if (buffer.position() != 0) buffer.position(0);
+        final FileHeader header = BinaryDictInputOutput.readHeader(buffer);
+
+        int wordPos = 0, address = buffer.position(), nodeOriginAddress = buffer.position();
+        final int[] codePoints = FusionDictionary.getCodePoints(word);
+        final int wordLen = codePoints.length;
+
+        for (int depth = 0; depth < Constants.DICTIONARY_MAX_WORD_LENGTH; ++depth) {
+            if (wordPos >= wordLen) break;
+            nodeOriginAddress = buffer.position();
+            int nodeParentAddress = -1;
+            final int charGroupCount = BinaryDictInputOutput.readCharGroupCount(buffer);
+            boolean foundNextGroup = false;
+
+            for (int i = 0; i < charGroupCount; ++i) {
+                address = buffer.position();
+                final CharGroupInfo currentInfo = BinaryDictInputOutput.readCharGroup(buffer,
+                        buffer.position(), header.mFormatOptions);
+                final boolean isMovedGroup = BinaryDictInputOutput.isMovedGroup(currentInfo.mFlags,
+                        header.mFormatOptions);
+                if (isMovedGroup) continue;
+                nodeParentAddress = (currentInfo.mParentAddress == FormatSpec.NO_PARENT_ADDRESS)
+                        ? FormatSpec.NO_PARENT_ADDRESS : currentInfo.mParentAddress + address;
+                boolean matched = true;
+                for (int p = 0; p < currentInfo.mCharacters.length; ++p) {
+                    if (wordPos + p >= wordLen) {
+                        /*
+                         * splitting
+                         * before
+                         *  abcd - ef
+                         *
+                         * insert "abc"
+                         *
+                         * after
+                         *  abc - d - ef
+                         */
+                        final int newNodeAddress = buffer.limit();
+                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(p > 1,
+                                isTerminal, 0, hasShortcuts, hasBigrams, false /* isNotAWord */,
+                                false /* isBlackListEntry */, header.mFormatOptions);
+                        int written = moveGroup(newNodeAddress, currentInfo.mCharacters, p, flags,
+                                frequency, nodeParentAddress, shortcuts, bigrams, destination,
+                                buffer, nodeOriginAddress, address, header.mFormatOptions);
+
+                        final int[] characters2 = Arrays.copyOfRange(currentInfo.mCharacters, p,
+                                currentInfo.mCharacters.length);
+                        if (currentInfo.mChildrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
+                            updateParentAddresses(buffer, currentInfo.mChildrenAddress,
+                                    newNodeAddress + written + 1, header.mFormatOptions);
+                        }
+                        final CharGroupInfo newInfo2 = new CharGroupInfo(
+                                newNodeAddress + written + 1, -1 /* endAddress */,
+                                currentInfo.mFlags, characters2, currentInfo.mFrequency,
+                                newNodeAddress + 1, currentInfo.mChildrenAddress,
+                                currentInfo.mShortcutTargets, currentInfo.mBigrams);
+                        BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[] { newInfo2 });
+                        return;
+                    } else if (codePoints[wordPos + p] != currentInfo.mCharacters[p]) {
+                        if (p > 0) {
+                            /*
+                             * splitting
+                             * before
+                             *   ab - cd
+                             *
+                             * insert "ac"
+                             *
+                             * after
+                             *   a - b - cd
+                             *     |
+                             *     - c
+                             */
+
+                            final int newNodeAddress = buffer.limit();
+                            final int childrenAddress = currentInfo.mChildrenAddress;
+
+                            // move prefix
+                            final int prefixFlags = BinaryDictInputOutput.makeCharGroupFlags(p > 1,
+                                    false /* isTerminal */, 0 /* childrenAddressSize*/,
+                                    false /* hasShortcut */, false /* hasBigrams */,
+                                    false /* isNotAWord */, false /* isBlackListEntry */,
+                                    header.mFormatOptions);
+                            int written = moveGroup(newNodeAddress, currentInfo.mCharacters, p,
+                                    prefixFlags, -1 /* frequency */, nodeParentAddress, null, null,
+                                    destination, buffer, nodeOriginAddress, address,
+                                    header.mFormatOptions);
+
+                            final int[] suffixCharacters = Arrays.copyOfRange(
+                                    currentInfo.mCharacters, p, currentInfo.mCharacters.length);
+                            if (currentInfo.mChildrenAddress != FormatSpec.NO_CHILDREN_ADDRESS) {
+                                updateParentAddresses(buffer, currentInfo.mChildrenAddress,
+                                        newNodeAddress + written + 1, header.mFormatOptions);
+                            }
+                            final int suffixFlags = BinaryDictInputOutput.makeCharGroupFlags(
+                                    suffixCharacters.length > 1,
+                                    (currentInfo.mFlags & FormatSpec.FLAG_IS_TERMINAL) != 0,
+                                    0 /* childrenAddressSize */,
+                                    (currentInfo.mFlags & FormatSpec.FLAG_HAS_SHORTCUT_TARGETS)
+                                            != 0,
+                                    (currentInfo.mFlags & FormatSpec.FLAG_HAS_BIGRAMS) != 0,
+                                    isNotAWord, isBlackListEntry, header.mFormatOptions);
+                            final CharGroupInfo suffixInfo = new CharGroupInfo(
+                                    newNodeAddress + written + 1, -1 /* endAddress */, suffixFlags,
+                                    suffixCharacters, currentInfo.mFrequency, newNodeAddress + 1,
+                                    currentInfo.mChildrenAddress, currentInfo.mShortcutTargets,
+                                    currentInfo.mBigrams);
+                            written += BinaryDictIOUtils.computeGroupSize(suffixInfo,
+                                    header.mFormatOptions) + 1;
+
+                            final int[] newCharacters = Arrays.copyOfRange(codePoints, wordPos + p,
+                                    codePoints.length);
+                            final int flags = BinaryDictInputOutput.makeCharGroupFlags(
+                                    newCharacters.length > 1, isTerminal,
+                                    0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
+                                    isNotAWord, isBlackListEntry, header.mFormatOptions);
+                            final CharGroupInfo newInfo = new CharGroupInfo(
+                                    newNodeAddress + written, -1 /* endAddress */, flags,
+                                    newCharacters, frequency, newNodeAddress + 1,
+                                    FormatSpec.NO_CHILDREN_ADDRESS, shortcuts, bigrams);
+                            BinaryDictIOUtils.writeNode(destination,
+                                    new CharGroupInfo[] { suffixInfo, newInfo });
+                            return;
+                        }
+                        matched = false;
+                        break;
+                    }
+                }
+
+                if (matched) {
+                    if (wordPos + currentInfo.mCharacters.length == wordLen) {
+                        // the word exists in the dictionary.
+                        // only update group.
+                        final int newNodeAddress = buffer.limit();
+                        final boolean hasMultipleChars = currentInfo.mCharacters.length > 1;
+                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(hasMultipleChars,
+                                isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
+                                isNotAWord, isBlackListEntry, header.mFormatOptions);
+                        final CharGroupInfo newInfo = new CharGroupInfo(newNodeAddress + 1,
+                                -1 /* endAddress */, flags, currentInfo.mCharacters, frequency,
+                                nodeParentAddress, currentInfo.mChildrenAddress, shortcuts,
+                                bigrams);
+                        moveCharGroup(destination, buffer, newInfo, nodeOriginAddress, address,
+                                header.mFormatOptions);
+                        return;
+                    }
+                    wordPos += currentInfo.mCharacters.length;
+                    if (currentInfo.mChildrenAddress == FormatSpec.NO_CHILDREN_ADDRESS) {
+                        /*
+                         * found the prefix of the word.
+                         * make new node and link to the node from this group.
+                         *
+                         * before
+                         * ab - cd
+                         *
+                         * insert "abcde"
+                         *
+                         * after
+                         * ab - cd - e
+                         */
+                        final int newNodeAddress = buffer.limit();
+                        updateChildrenAddress(buffer, address, newNodeAddress,
+                                header.mFormatOptions);
+                        final int newGroupAddress = newNodeAddress + 1;
+                        final boolean hasMultipleChars = (wordLen - wordPos) > 1;
+                        final int flags = BinaryDictInputOutput.makeCharGroupFlags(hasMultipleChars,
+                                isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
+                                isNotAWord, isBlackListEntry, header.mFormatOptions);
+                        final int[] characters = Arrays.copyOfRange(codePoints, wordPos, wordLen);
+                        final CharGroupInfo newInfo = new CharGroupInfo(newGroupAddress, -1, flags,
+                                characters, frequency, address, FormatSpec.NO_CHILDREN_ADDRESS,
+                                shortcuts, bigrams);
+                        BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[] { newInfo });
+                        return;
+                    }
+                    buffer.position(currentInfo.mChildrenAddress);
+                    foundNextGroup = true;
+                    break;
+                }
+            }
+
+            if (foundNextGroup) continue;
+
+            // reached the end of the array.
+            final int linkAddressPosition = buffer.position();
+            int nextLink = buffer.readUnsignedInt24();
+            if ((nextLink & FormatSpec.MSB24) != 0) {
+                nextLink = -(nextLink & FormatSpec.SINT24_MAX);
+            }
+            if (nextLink == FormatSpec.NO_FORWARD_LINK_ADDRESS) {
+                /*
+                 * expand this node.
+                 *
+                 * before
+                 * ab - cd
+                 *
+                 * insert "abef"
+                 *
+                 * after
+                 * ab - cd
+                 *    |
+                 *    - ef
+                 */
+
+                // change the forward link address.
+                final int newNodeAddress = buffer.limit();
+                buffer.position(linkAddressPosition);
+                BinaryDictIOUtils.writeSInt24ToBuffer(buffer, newNodeAddress);
+
+                final int[] characters = Arrays.copyOfRange(codePoints, wordPos, wordLen);
+                final int flags = BinaryDictInputOutput.makeCharGroupFlags(characters.length > 1,
+                        isTerminal, 0 /* childrenAddressSize */, hasShortcuts, hasBigrams,
+                        isNotAWord, isBlackListEntry, header.mFormatOptions);
+                final CharGroupInfo newInfo = new CharGroupInfo(newNodeAddress + 1,
+                        -1 /* endAddress */, flags, characters, frequency, nodeParentAddress,
+                        FormatSpec.NO_CHILDREN_ADDRESS, shortcuts, bigrams);
+                BinaryDictIOUtils.writeNode(destination, new CharGroupInfo[]{ newInfo });
+                return;
+            } else {
+                depth--;
+                buffer.position(nextLink);
+            }
+        }
+    }
+}
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java
index e4b5ad2..7bfd603 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOTests.java
@@ -619,13 +619,13 @@
         try {
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD,
                     BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(0)));
-            BinaryDictIOUtils.deleteWord(buffer, sWords.get(0));
+            DynamicBinaryDictIOUtils.deleteWord(buffer, sWords.get(0));
             assertEquals(FormatSpec.NOT_VALID_WORD,
                     BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(0)));
 
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD,
                     BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(5)));
-            BinaryDictIOUtils.deleteWord(buffer, sWords.get(5));
+            DynamicBinaryDictIOUtils.deleteWord(buffer, sWords.get(5));
             assertEquals(FormatSpec.NOT_VALID_WORD,
                     BinaryDictIOUtils.getTerminalPosition(buffer, sWords.get(5)));
         } catch (IOException e) {
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
index 9331da4..e759507 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictIOUtilsTests.java
@@ -197,8 +197,8 @@
                 assertEquals(FormatSpec.NOT_VALID_WORD, getWordPosition(file, word));
             }
             final long now = System.nanoTime();
-            BinaryDictIOUtils.insertWord(buffer, outStream, word, frequency, bigrams, shortcuts,
-                    false, false);
+            DynamicBinaryDictIOUtils.insertWord(buffer, outStream, word, frequency, bigrams,
+                    shortcuts, false, false);
             amountOfTime = System.nanoTime() - now;
             outStream.flush();
             MoreAsserts.assertNotEqual(FormatSpec.NOT_VALID_WORD, getWordPosition(file, word));
@@ -232,7 +232,7 @@
             raFile = new RandomAccessFile(file, "rw");
             buffer = new ByteBufferWrapper(raFile.getChannel().map(
                     FileChannel.MapMode.READ_WRITE, 0, file.length()));
-            BinaryDictIOUtils.deleteWord(buffer, word);
+            DynamicBinaryDictIOUtils.deleteWord(buffer, word);
         } catch (IOException e) {
         } catch (UnsupportedFormatException e) {
         } finally {