diff --git a/java/src/com/android/inputmethod/latin/makedict/SparseTableContentWriter.java b/java/src/com/android/inputmethod/latin/makedict/SparseTableContentWriter.java
new file mode 100644
index 0000000..49f0fd6
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/makedict/SparseTableContentWriter.java
@@ -0,0 +1,93 @@
+/*
+ * 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 java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * An auxiliary class for writing data associated with SparseTable to files.
+ */
+public class SparseTableContentWriter {
+    public interface SparseTableContentWriterInterface {
+        public void write(final OutputStream outStream) throws IOException;
+    }
+
+    private final int mContentCount;
+    private final SparseTable mSparseTable;
+    private final File mLookupTableFile;
+    protected final File mBaseDir;
+    private final File[] mAddressTableFiles;
+    private final File[] mContentFiles;
+    protected final OutputStream[] mContentOutStreams;
+
+    /**
+     * Sole constructor of SparseTableContentWriter.
+     *
+     * @param name the name of SparseTable.
+     * @param initialCapacity the initial capacity of SparseTable.
+     * @param blockSize the block size of the content table.
+     * @param baseDir the directory which contains the files of the content table.
+     * @param contentFilenames the file names of content files.
+     * @param contentIds the ids of contents. These ids are used for a suffix of a name of address
+     * files and content files.
+     */
+    public SparseTableContentWriter(final String name, final int initialCapacity,
+            final int blockSize, final File baseDir, final String[] contentFilenames,
+            final String[] contentIds) {
+        if (contentFilenames.length != contentIds.length) {
+            throw new RuntimeException("The length of contentFilenames and the length of"
+                    + " contentIds are different " + contentFilenames.length + ", "
+                    + contentIds.length);
+        }
+        mContentCount = contentFilenames.length;
+        mSparseTable = new SparseTable(initialCapacity, blockSize, mContentCount);
+        mLookupTableFile = new File(baseDir, name + FormatSpec.LOOKUP_TABLE_FILE_SUFFIX);
+        mAddressTableFiles = new File[mContentCount];
+        mContentFiles = new File[mContentCount];
+        mBaseDir = baseDir;
+        for (int i = 0; i < mContentCount; ++i) {
+            mAddressTableFiles[i] = new File(mBaseDir,
+                    name + FormatSpec.CONTENT_TABLE_FILE_SUFFIX + contentIds[i]);
+            mContentFiles[i] = new File(mBaseDir, contentFilenames[i] + contentIds[i]);
+        }
+        mContentOutStreams = new OutputStream[mContentCount];
+    }
+
+    public void openStreams() throws FileNotFoundException {
+        for (int i = 0; i < mContentCount; ++i) {
+            mContentOutStreams[i] = new FileOutputStream(mContentFiles[i]);
+        }
+    }
+
+    protected void write(final int contentIndex, final int index,
+            final SparseTableContentWriterInterface writer) throws IOException {
+        mSparseTable.set(contentIndex, index, (int) mContentFiles[contentIndex].length());
+        writer.write(mContentOutStreams[contentIndex]);
+        mContentOutStreams[contentIndex].flush();
+    }
+
+    public void closeStreams() throws IOException {
+        mSparseTable.writeToFiles(mLookupTableFile, mAddressTableFiles);
+        for (int i = 0; i < mContentCount; ++i) {
+            mContentOutStreams[i].close();
+        }
+    }
+}
\ No newline at end of file
diff --git a/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java b/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
index 5d5ab04..8424274 100644
--- a/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
@@ -57,62 +57,6 @@
         mDictPlacedDir = dictPlacedDir;
     }
 
-    private interface SparseTableContentWriterInterface {
-        public void write(final OutputStream outStream) throws IOException;
-    }
-
-    private static class SparseTableContentWriter {
-        private final int mContentCount;
-        private final SparseTable mSparseTable;
-        private final File mLookupTableFile;
-        protected final File mBaseDir;
-        private final File[] mAddressTableFiles;
-        private final File[] mContentFiles;
-        protected final OutputStream[] mContentOutStreams;
-
-        public SparseTableContentWriter(final String name, final int initialCapacity,
-                final int blockSize, final File baseDir, final String[] contentFilenames,
-                final String[] contentIds) {
-            if (contentFilenames.length != contentIds.length) {
-                throw new RuntimeException("The length of contentFilenames and the length of"
-                        + " contentIds are different " + contentFilenames.length + ", "
-                        + contentIds.length);
-            }
-            mContentCount = contentFilenames.length;
-            mSparseTable = new SparseTable(initialCapacity, blockSize, mContentCount);
-            mLookupTableFile = new File(baseDir, name + FormatSpec.LOOKUP_TABLE_FILE_SUFFIX);
-            mAddressTableFiles = new File[mContentCount];
-            mContentFiles = new File[mContentCount];
-            mBaseDir = baseDir;
-            for (int i = 0; i < mContentCount; ++i) {
-                mAddressTableFiles[i] = new File(mBaseDir,
-                        name + FormatSpec.CONTENT_TABLE_FILE_SUFFIX + contentIds[i]);
-                mContentFiles[i] = new File(mBaseDir, contentFilenames[i] + contentIds[i]);
-            }
-            mContentOutStreams = new OutputStream[mContentCount];
-        }
-
-        public void openStreams() throws FileNotFoundException {
-            for (int i = 0; i < mContentCount; ++i) {
-                mContentOutStreams[i] = new FileOutputStream(mContentFiles[i]);
-            }
-        }
-
-        protected void write(final int contentIndex, final int index,
-                final SparseTableContentWriterInterface writer) throws IOException {
-            mSparseTable.set(contentIndex, index, (int) mContentFiles[contentIndex].length());
-            writer.write(mContentOutStreams[contentIndex]);
-            mContentOutStreams[contentIndex].flush();
-        }
-
-        public void closeStreams() throws IOException {
-            mSparseTable.writeToFiles(mLookupTableFile, mAddressTableFiles);
-            for (int i = 0; i < mContentCount; ++i) {
-                mContentOutStreams[i].close();
-            }
-        }
-    }
-
     private static class BigramContentWriter extends SparseTableContentWriter {
         private final boolean mWriteTimestamp;