- remove arrays.xml

- clean up keys.xml
- clean up do_not_translate.xml

MyTracks/src/com/google/android/apps/mytracks/io/backup/BackupActivityHelper.java

@@ -0,0 +1,244 @@
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import com.google.android.apps.mytracks.Constants;
+import com.google.android.apps.mytracks.MyTracks;
+import com.google.android.apps.mytracks.util.FileUtils;
+import com.google.android.maps.mytracks.R;
+
+import android.app.Activity;
+import android.app.AlertDialog;
+import android.app.AlertDialog.Builder;
+import android.app.Dialog;
+import android.app.ProgressDialog;
+import android.content.DialogInterface;
+import android.content.DialogInterface.OnClickListener;
+import android.content.Intent;
+import android.util.Log;
+import android.widget.Toast;
+
+import java.io.IOException;
+import java.text.SimpleDateFormat;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.Date;
+
+/**
+ * Helper which shows a UI for writing or restoring a backup,
+ * and calls the appropriate handler for actually executing those
+ * operations.
+ *
+ * @author Rodrigo Damazio
+ */
+public class BackupActivityHelper {
+
+  // Since the user sees this format, we use the local timezone
+  private static final SimpleDateFormat DISPLAY_BACKUP_FORMAT =
+      new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+
+  private static final Comparator<Date> REVERSE_DATE_ORDER =
+      new Comparator<Date>() {
+        @Override
+        public int compare(Date s1, Date s2) {
+          return s2.compareTo(s1);
+        }
+      };
+
+  private final FileUtils fileUtils;
+  private final ExternalFileBackup backup;
+  private final Activity activity;
+
+  public BackupActivityHelper(Activity activity) {
+    this.activity = activity;
+    this.fileUtils = new FileUtils();
+    this.backup = new ExternalFileBackup(activity, fileUtils);
+  }
+
+  /**
+   * Writes a full backup to the default file.
+   * This shows the results to the user.
+   */
+  public void writeBackup() {
+    if (!fileUtils.isSdCardAvailable()) {
+      showToast(R.string.io_no_external_storage_found);
+      return;
+    }
+
+    if (!backup.isBackupsDirectoryAvailable(true)) {
+      showToast(R.string.io_create_dir_failed);
+      return;
+    }
+
+    final ProgressDialog progressDialog = ProgressDialog.show(
+        activity,
+        activity.getString(R.string.progress_title),
+        activity.getString(R.string.backup_write_progress_message),
+        true);
+
+    // Do the writing in another thread
+    new Thread() {
+      @Override
+      public void run() {
+        try {
+          backup.writeToDefaultFile();
+          showToast(R.string.io_write_finished);
+        } catch (IOException e) {
+          Log.e(Constants.TAG, "Failed to write backup", e);
+          showToast(R.string.io_write_failed);
+        } finally {
+          dismissDialog(progressDialog);
+        }
+      }
+    }.start();
+  }
+
+  /**
+   * Restores a full backup from the SD card.
+   * The user will be given a choice of which backup to restore as well as a
+   * confirmation dialog.
+   */
+  public void restoreBackup() {
+    // Get the list of existing backups
+    if (!fileUtils.isSdCardAvailable()) {
+      showToast(R.string.io_no_external_storage_found);
+      return;
+    }
+
+    if (!backup.isBackupsDirectoryAvailable(false)) {
+      showToast(R.string.no_backups);
+      return;
+    }
+
+    final Date[] backupDates = backup.getAvailableBackups();
+    if (backupDates == null || backupDates.length == 0) {
+      showToast(R.string.no_backups);
+      return;
+    }
+    Arrays.sort(backupDates, REVERSE_DATE_ORDER);
+
+    // Show a confirmation dialog
+    Builder confirmationDialogBuilder = new AlertDialog.Builder(activity);
+    confirmationDialogBuilder.setMessage(R.string.restore_overwrites_warning);
+    confirmationDialogBuilder.setCancelable(true);
+    confirmationDialogBuilder.setPositiveButton(android.R.string.yes,
+        new OnClickListener() {
+          @Override
+          public void onClick(DialogInterface dialog, int which) {
+            pickBackupForRestore(backupDates);
+          }
+        });
+    confirmationDialogBuilder.setNegativeButton(android.R.string.no, null);
+    confirmationDialogBuilder.create().show();
+  }
+
+  /**
+   * Shows a backup list for the user to pick, then restores it.
+   *
+   * @param backupDates the list of available backup files
+   */
+  private void pickBackupForRestore(final Date[] backupDates) {
+    if (backupDates.length == 1) {
+      // Only one choice, don't bother showing the list
+      restoreFromDateAsync(backupDates[0]);
+      return;
+    }
+
+    // Make a user-visible version of the backup filenames
+    final String backupDateStrs[] = new String[backupDates.length];
+    for (int i = 0; i < backupDates.length; i++) {
+      backupDateStrs[i] = DISPLAY_BACKUP_FORMAT.format(backupDates[i]);
+    }
+
+    // Show a dialog for the user to pick which backup to restore
+    Builder dialogBuilder = new AlertDialog.Builder(activity);
+    dialogBuilder.setCancelable(true);
+    dialogBuilder.setTitle(R.string.select_backup_to_restore);
+    dialogBuilder.setItems(backupDateStrs, new OnClickListener() {
+      @Override
+      public void onClick(DialogInterface dialog, int which) {
+        // User picked to restore this one
+        restoreFromDateAsync(backupDates[which]);
+      }
+    });
+    dialogBuilder.create().show();
+  }
+
+  /**
+   * Shows a progress dialog, then starts restoring the backup asynchronously.
+   *
+   * @param date the date
+   */
+  private void restoreFromDateAsync(final Date date) {
+    // Show a progress dialog
+    ProgressDialog.show(
+        activity,
+        activity.getString(R.string.progress_title),
+        activity.getString(R.string.backup_import_progress_message),
+        true);
+
+    // Do the actual importing in another thread (don't block the UI)
+    new Thread() {
+      @Override
+      public void run() {
+        try {
+          backup.restoreFromDate(date);
+          showToast(R.string.io_read_finished);
+        } catch (IOException e) {
+          Log.e(Constants.TAG, "Failed to restore backup", e);
+          showToast(R.string.io_read_failed);
+        } finally {
+          // Data may have been restored, "reboot" the app to catch it
+          restartApplication();
+        }
+      }
+    }.start();
+  }
+
+  /**
+   * Restarts My Tracks completely.
+   * This forces any modified data to be re-read.
+   */
+  private void restartApplication() {
+    Intent intent = new Intent(activity, MyTracks.class);
+    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
+    activity.startActivity(intent);
+  }
+
+  /**
+   * Shows a toast with the given contents.
+   */
+  private void showToast(final int resId) {
+    activity.runOnUiThread(new Runnable() {
+      @Override
+      public void run() {
+        Toast.makeText(activity, resId, Toast.LENGTH_LONG).show();
+      }
+    });
+  }
+
+  /**
+   * Safely dismisses the given dialog.
+   */
+  private void dismissDialog(final Dialog dialog) {
+    activity.runOnUiThread(new Runnable() {
+      @Override
+      public void run() {
+        dialog.dismiss();
+      }
+    });
+  }
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/BackupColumns.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2010 Google Inc.
+ * 
+ * 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.google.android.apps.mytracks.io.backup;
+
+import static com.google.android.apps.mytracks.content.ContentTypeIds.*;
+import com.google.android.apps.mytracks.content.TrackPointsColumns;
+import com.google.android.apps.mytracks.content.TracksColumns;
+import com.google.android.apps.mytracks.content.WaypointsColumns;
+
+public class BackupColumns {
+  /** Columns that go into the backup. */
+  public static final String[] POINTS_BACKUP_COLUMNS =
+      { TrackPointsColumns._ID, TrackPointsColumns.TRACKID, TrackPointsColumns.LATITUDE,
+        TrackPointsColumns.LONGITUDE, TrackPointsColumns.ALTITUDE, TrackPointsColumns.BEARING,
+        TrackPointsColumns.TIME, TrackPointsColumns.ACCURACY, TrackPointsColumns.SPEED,
+        TrackPointsColumns.SENSOR };
+  public static final byte[] POINTS_BACKUP_COLUMN_TYPES =
+      { LONG_TYPE_ID, LONG_TYPE_ID, INT_TYPE_ID, INT_TYPE_ID, FLOAT_TYPE_ID,
+        FLOAT_TYPE_ID, LONG_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID, BLOB_TYPE_ID };
+
+  public static final String[] TRACKS_BACKUP_COLUMNS = {
+      TracksColumns._ID, TracksColumns.NAME, TracksColumns.DESCRIPTION, TracksColumns.CATEGORY,
+      TracksColumns.STARTID, TracksColumns.STOPID, TracksColumns.STARTTIME, TracksColumns.STOPTIME,
+      TracksColumns.NUMPOINTS, TracksColumns.TOTALDISTANCE, TracksColumns.TOTALTIME,
+      TracksColumns.MOVINGTIME, TracksColumns.AVGSPEED, TracksColumns.AVGMOVINGSPEED,
+      TracksColumns.MAXSPEED, TracksColumns.MINELEVATION, TracksColumns.MAXELEVATION,
+      TracksColumns.ELEVATIONGAIN, TracksColumns.MINGRADE, TracksColumns.MAXGRADE,
+      TracksColumns.MINLAT, TracksColumns.MAXLAT, TracksColumns.MINLON, TracksColumns.MAXLON,
+      TracksColumns.MAPID, TracksColumns.TABLEID};
+  public static final byte[] TRACKS_BACKUP_COLUMN_TYPES = {
+      LONG_TYPE_ID, STRING_TYPE_ID, STRING_TYPE_ID, STRING_TYPE_ID,
+      LONG_TYPE_ID, LONG_TYPE_ID, LONG_TYPE_ID, LONG_TYPE_ID, INT_TYPE_ID,
+      FLOAT_TYPE_ID, LONG_TYPE_ID, LONG_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID,
+      FLOAT_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID,
+      FLOAT_TYPE_ID, INT_TYPE_ID, INT_TYPE_ID, INT_TYPE_ID, INT_TYPE_ID, STRING_TYPE_ID,
+      STRING_TYPE_ID};
+
+  public static final String[] WAYPOINTS_BACKUP_COLUMNS = {
+      WaypointsColumns._ID, WaypointsColumns.TRACKID, WaypointsColumns.NAME,
+      WaypointsColumns.DESCRIPTION, WaypointsColumns.CATEGORY, WaypointsColumns.ICON,
+      WaypointsColumns.TYPE, WaypointsColumns.LENGTH, WaypointsColumns.DURATION,
+      WaypointsColumns.STARTTIME, WaypointsColumns.STARTID, WaypointsColumns.STOPID,
+      WaypointsColumns.LATITUDE, WaypointsColumns.LONGITUDE, WaypointsColumns.ALTITUDE,
+      WaypointsColumns.BEARING, WaypointsColumns.TIME, WaypointsColumns.ACCURACY,
+      WaypointsColumns.SPEED, WaypointsColumns.TOTALDISTANCE, WaypointsColumns.TOTALTIME,
+      WaypointsColumns.MOVINGTIME, WaypointsColumns.AVGSPEED, WaypointsColumns.AVGMOVINGSPEED,
+      WaypointsColumns.MAXSPEED, WaypointsColumns.MINELEVATION, WaypointsColumns.MAXELEVATION,
+      WaypointsColumns.ELEVATIONGAIN, WaypointsColumns.MINGRADE, WaypointsColumns.MAXGRADE };
+  public static final byte[] WAYPOINTS_BACKUP_COLUMN_TYPES = {
+      LONG_TYPE_ID, LONG_TYPE_ID, STRING_TYPE_ID, STRING_TYPE_ID,
+      STRING_TYPE_ID, STRING_TYPE_ID, INT_TYPE_ID, FLOAT_TYPE_ID, LONG_TYPE_ID,
+      LONG_TYPE_ID, LONG_TYPE_ID, LONG_TYPE_ID, INT_TYPE_ID, INT_TYPE_ID,
+      FLOAT_TYPE_ID, FLOAT_TYPE_ID, LONG_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID,
+      FLOAT_TYPE_ID, LONG_TYPE_ID, LONG_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID,
+      FLOAT_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID, FLOAT_TYPE_ID,
+      FLOAT_TYPE_ID };
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/BackupPreferencesListener.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
+
+/**
+ * Shared preferences listener which notifies the backup system about new data
+ * being available for backup.
+ *
+ * @author Rodrigo Damazio
+ */
+public interface BackupPreferencesListener extends OnSharedPreferenceChangeListener {
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/BackupPreferencesListenerImpl.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2011 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import android.app.backup.BackupManager;
+import android.content.Context;
+import android.content.SharedPreferences;
+
+/**
+ * Implementation of {@link BackupPreferencesListener} that calls the
+ * {@link BackupManager}.
+ *
+ * @author Jimmy Shih
+ */
+public class BackupPreferencesListenerImpl implements BackupPreferencesListener {
+
+  private final BackupManager backupManager;
+
+  public BackupPreferencesListenerImpl(Context context) {
+    this.backupManager = new BackupManager(context);
+  }
+
+  @Override
+  public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
+    backupManager.dataChanged();
+  }
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/DatabaseDumper.java

@@ -0,0 +1,248 @@
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import com.google.android.apps.mytracks.content.ContentTypeIds;
+
+import android.database.Cursor;
+import android.database.MergeCursor;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+
+/**
+ * Database dumper which is able to write only part of the database
+ * according to some query.
+ *
+ * This dumper is symmetrical to {@link DatabaseImporter}.
+ *
+ * @author Rodrigo Damazio
+ */
+class DatabaseDumper {
+
+  /** The names of the columns being dumped. */
+  private final String[] columnNames;
+  /** The types of the columns being dumped. */
+  private final byte[] columnTypes;
+  /** Whether to output null fields. */
+  private final boolean outputNullFields;
+
+  // Temporary state
+  private int[] columnIndices;
+  private boolean[] hasFields;
+
+  public DatabaseDumper(String[] columnNames, byte[] columnTypes,
+      boolean outputNullFields) {
+    if (columnNames.length != columnTypes.length) {
+      throw new IllegalArgumentException("Names don't match types");
+    }
+
+    this.columnNames = columnNames;
+    this.columnTypes = columnTypes;
+    this.outputNullFields = outputNullFields;
+  }
+
+  /**
+   * Writes the header plus all rows that can be read from the given cursor.
+   * This assumes the cursor will have the same column and column indices on
+   * every row (and thus may not work with a {@link MergeCursor}).
+   */
+  public void writeAllRows(Cursor cursor, DataOutputStream writer)
+      throws IOException {
+    writeHeaders(cursor, cursor.getCount(), writer);
+
+    if (!cursor.moveToFirst()) {
+      return;
+    }
+
+    do {
+      writeOneRow(cursor, writer);
+    } while (cursor.moveToNext());
+  }
+
+  /**
+   * Writes just the headers for the data that will come from the given cursor.
+   * The headers include column information and the number of rows that will be
+   * written.
+   *
+   * @param cursor the cursor to get columns from
+   * @param numRows the number of rows that will be later written
+   * @param writer the output to write to
+   * @throws IOException if there are errors while writing
+   */
+  public void writeHeaders(Cursor cursor, int numRows, DataOutputStream writer)
+      throws IOException {
+    initializeCachedValues(cursor);
+    writeQueryMetadata(numRows, writer);
+  }
+
+  /**
+   * Writes the current row from the cursor. The cursor is not advanced.
+   * This must be called after {@link #writeHeaders}.
+   *
+   * @param cursor the cursor to write data from
+   * @param writer the output to write to
+   * @throws IOException if there are any errors while writing
+   */
+  public void writeOneRow(Cursor cursor, DataOutputStream writer)
+      throws IOException {
+    if (columnIndices == null) {
+      throw new IllegalStateException(
+          "Cannot write rows before writing the header");
+    }
+
+    if (columnIndices.length > Long.SIZE) {
+      throw new IllegalArgumentException("Too many fields");
+    }
+
+    // Build a bitmap of which fields are present
+    long fields = 0;
+    for (int i = 0; i < columnIndices.length; i++) {
+      hasFields[i] = !cursor.isNull(columnIndices[i]);
+      fields |= (hasFields[i] ? 1 : 0) << i;
+    }
+    writer.writeLong(fields);
+
+    // Actually write the present fields
+    for (int i = 0; i < columnIndices.length; i++) {
+      if (hasFields[i]) {
+        writeCell(columnIndices[i], columnTypes[i], cursor, writer);
+      } else if (outputNullFields) {
+        writeDummyCell(columnTypes[i], writer);
+      }
+    }
+  }
+
+  /**
+   * Initializes the column indices and other temporary state for reading from
+   * the given cursor.
+   */
+  private void initializeCachedValues(Cursor cursor) {
+    // These indices are constant for every row (unless we're fed a MergeCursor)
+    if (cursor instanceof MergeCursor) {
+      throw new IllegalArgumentException("Cannot use a MergeCursor");
+    }
+
+    columnIndices = new int[columnNames.length];
+    for (int i = 0; i < columnNames.length; i++) {
+      String columnName = columnNames[i];
+      columnIndices[i] = cursor.getColumnIndexOrThrow(columnName);
+    }
+
+    hasFields = new boolean[columnIndices.length];
+  }
+
+  /**
+   * Writes metadata about the query to be dumped.
+   *
+   * @param numRows the number of rows that will be dumped
+   * @param writer the output to write to
+   * @throws IOException if there are any errors while writing
+   */
+  private void writeQueryMetadata(
+      int numRows, DataOutputStream writer) throws IOException {
+    // Write column data
+    writer.writeInt(columnNames.length);
+    for (int i = 0; i < columnNames.length; i++) {
+      String columnName = columnNames[i];
+      byte columnType = columnTypes[i];
+      writer.writeUTF(columnName);
+      writer.writeByte(columnType);
+    }
+
+    // Write the number of rows
+    writer.writeInt(numRows);
+  }
+
+  /**
+   * Writes a single cell of the database to the output.
+   *
+   * @param columnIdx the column index to read from
+   * @param columnTypeId the type of the column to be read
+   * @param cursor the cursor to read from
+   * @param writer the output to write to
+   * @throws IOException if there are any errors while writing
+   */
+  private void writeCell(
+      int columnIdx, byte columnTypeId, Cursor cursor, DataOutputStream writer)
+      throws IOException {
+    switch (columnTypeId) {
+      case ContentTypeIds.LONG_TYPE_ID:
+        writer.writeLong(cursor.getLong(columnIdx));
+        return;
+      case ContentTypeIds.DOUBLE_TYPE_ID:
+        writer.writeDouble(cursor.getDouble(columnIdx));
+        return;
+      case ContentTypeIds.FLOAT_TYPE_ID:
+        writer.writeFloat(cursor.getFloat(columnIdx));
+        return;
+      case ContentTypeIds.BOOLEAN_TYPE_ID:
+        writer.writeBoolean(cursor.getInt(columnIdx) != 0);
+        return;
+      case ContentTypeIds.INT_TYPE_ID:
+        writer.writeInt(cursor.getInt(columnIdx));
+        return;
+      case ContentTypeIds.STRING_TYPE_ID:
+        writer.writeUTF(cursor.getString(columnIdx));
+        return;
+      case ContentTypeIds.BLOB_TYPE_ID: {
+        byte[] blob = cursor.getBlob(columnIdx);
+        writer.writeInt(blob.length);
+        writer.write(blob);
+        return;
+      }
+      default:
+        throw new IllegalArgumentException(
+            "Type " + columnTypeId + " not supported");
+    }
+  }
+
+  /**
+   * Writes a dummy cell value to the output.
+   *
+   * @param columnTypeId the type of the value to write
+   * @throws IOException if there are any errors while writing
+   */
+  private void writeDummyCell(byte columnTypeId, DataOutputStream writer)
+      throws IOException {
+    switch (columnTypeId) {
+      case ContentTypeIds.LONG_TYPE_ID:
+        writer.writeLong(0L);
+        return;
+      case ContentTypeIds.DOUBLE_TYPE_ID:
+        writer.writeDouble(0.0);
+        return;
+      case ContentTypeIds.FLOAT_TYPE_ID:
+        writer.writeFloat(0.0f);
+        return;
+      case ContentTypeIds.BOOLEAN_TYPE_ID:
+        writer.writeBoolean(false);
+        return;
+      case ContentTypeIds.INT_TYPE_ID:
+        writer.writeInt(0);
+        return;
+      case ContentTypeIds.STRING_TYPE_ID:
+        writer.writeUTF("");
+        return;
+      case ContentTypeIds.BLOB_TYPE_ID:
+        writer.writeInt(0);
+        return;
+      default:
+        throw new IllegalArgumentException(
+            "Type " + columnTypeId + " not supported");
+    }
+  }
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/DatabaseImporter.java

@@ -0,0 +1,197 @@
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import com.google.android.apps.mytracks.content.ContentTypeIds;
+
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.net.Uri;
+
+import java.io.DataInputStream;
+import java.io.IOException;
+
+/**
+ * Database importer which reads values written by {@link DatabaseDumper}.
+ *
+ * @author Rodrigo Damazio
+ */
+public class DatabaseImporter {
+
+  /** Maximum number of entries in a bulk insertion */
+  private static final int DEFAULT_BULK_SIZE = 1024;
+
+  private final Uri destinationUri;
+  private final ContentResolver resolver;
+  private final boolean readNullFields;
+  private final int bulkSize;
+
+  // Metadata read from the reader
+  private String[] columnNames;
+  private byte[] columnTypes;
+
+  public DatabaseImporter(Uri destinationUri, ContentResolver resolver,
+      boolean readNullFields) {
+    this(destinationUri, resolver, readNullFields, DEFAULT_BULK_SIZE);
+  }
+
+  protected DatabaseImporter(Uri destinationUri, ContentResolver resolver,
+      boolean readNullFields, int bulkSize) {
+    this.destinationUri = destinationUri;
+    this.resolver = resolver;
+    this.readNullFields = readNullFields;
+    this.bulkSize = bulkSize;
+  }
+
+  /**
+   * Reads the header which includes metadata about the table being imported.
+   *
+   * @throws IOException if there are any problems while reading
+   */
+  private void readHeaders(DataInputStream reader) throws IOException {
+    int numColumns = reader.readInt();
+    columnNames = new String[numColumns];
+    columnTypes = new byte[numColumns];
+    for (int i = 0; i < numColumns; i++) {
+      columnNames[i] = reader.readUTF();
+      columnTypes[i] = reader.readByte();
+    }
+  }
+
+  /**
+   * Imports all rows from the reader into the database.
+   * Insertion is done in bulks for efficiency.
+   *
+   * @throws IOException if there are any errors while reading
+   */
+  public void importAllRows(DataInputStream reader) throws IOException {
+    readHeaders(reader);
+
+    ContentValues[] valueBulk = new ContentValues[bulkSize];
+    int numValues = 0;
+
+    int numRows = reader.readInt();
+    int numColumns = columnNames.length;
+
+    // For each row
+    for (int r = 0; r < numRows; r++) {
+      if (valueBulk[numValues] == null) {
+        valueBulk[numValues] = new ContentValues(numColumns);
+      } else {
+        // Reuse values objects
+        valueBulk[numValues].clear();
+      }
+
+      // Read the fields bitmap
+      long fields = reader.readLong();
+      for (int c = 0; c < numColumns; c++) {
+        if ((fields & 1) == 1) {
+          // Field is present, read into values
+          readOneCell(columnNames[c], columnTypes[c], valueBulk[numValues],
+              reader);
+        } else if (readNullFields) {
+          // Field not present but still written, read and discard
+          readOneCell(columnNames[c], columnTypes[c], null, reader);
+        }
+
+        fields >>= 1;
+      }
+
+      numValues++;
+
+      // If we have enough values, flush them as a bulk insertion
+      if (numValues >= bulkSize) {
+        doBulkInsert(valueBulk);
+        numValues = 0;
+      }
+    }
+
+    // Do a final bulk insert with the leftovers
+    if (numValues > 0) {
+      ContentValues[] leftovers = new ContentValues[numValues];
+      System.arraycopy(valueBulk, 0, leftovers, 0, numValues);
+      doBulkInsert(leftovers);
+    }
+  }
+
+  protected void doBulkInsert(ContentValues[] values) {
+    resolver.bulkInsert(destinationUri, values);
+  }
+
+  /**
+   * Reads a single cell from the reader.
+   *
+   * @param name the name of the column to be read
+   * @param typeId the type ID of the column to be read
+   * @param values the {@link ContentValues} object to put the read cell value
+   *        in - if null, the value is just discarded
+   * @throws IOException if there are any problems while reading
+   */
+  private void readOneCell(String name, byte typeId, ContentValues values,
+      DataInputStream reader) throws IOException {
+    switch (typeId) {
+      case ContentTypeIds.BOOLEAN_TYPE_ID: {
+        boolean value = reader.readBoolean();
+        if (values != null) { values.put(name, value); }
+        return;
+      }
+      case ContentTypeIds.LONG_TYPE_ID: {
+        long value = reader.readLong();
+        if (values != null) { values.put(name, value); }
+        return;
+      }
+      case ContentTypeIds.DOUBLE_TYPE_ID: {
+        double value = reader.readDouble();
+        if (values != null) { values.put(name, value); }
+        return;
+      }
+      case ContentTypeIds.FLOAT_TYPE_ID: {
+        Float value = reader.readFloat();
+        if (values != null) { values.put(name, value); }
+        return;
+      }
+      case ContentTypeIds.INT_TYPE_ID: {
+        int value = reader.readInt();
+        if (values != null) { values.put(name, value); }
+        return;
+      }
+      case ContentTypeIds.STRING_TYPE_ID: {
+        String value = reader.readUTF();
+        if (values != null) { values.put(name, value); }
+        return;
+      }
+      case ContentTypeIds.BLOB_TYPE_ID: {
+        int blobLength = reader.readInt();
+        if (blobLength != 0) {
+          byte[] blob = new byte[blobLength];
+          int readBytes = reader.read(blob, 0, blobLength);
+          if (readBytes != blobLength) {
+            throw new IOException(String.format(
+                "Short read on column %s; expected %d bytes, read %d",
+                name, blobLength, readBytes));
+          }
+          
+          if (values != null) {
+            values.put(name, blob);
+          }
+        }
+        return;
+      }
+      default:
+        throw new IOException("Read unknown type " + typeId);
+    }
+  }
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/ExternalFileBackup.java

@@ -0,0 +1,266 @@
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import static com.google.android.apps.mytracks.Constants.TAG;
+
+import com.google.android.apps.mytracks.Constants;
+import com.google.android.apps.mytracks.content.TrackPointsColumns;
+import com.google.android.apps.mytracks.content.TracksColumns;
+import com.google.android.apps.mytracks.content.WaypointsColumns;
+import com.google.android.apps.mytracks.util.FileUtils;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.database.Cursor;
+import android.util.Log;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+import java.util.TimeZone;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+import java.util.zip.ZipOutputStream;
+
+/**
+ * Handler for writing or reading single-file backups.
+ *
+ * @author Rodrigo Damazio
+ */
+class ExternalFileBackup {
+  // Filename format - in UTC
+  private static final SimpleDateFormat BACKUP_FILENAME_FORMAT =
+      new SimpleDateFormat("'backup-'yyyy-MM-dd_HH-mm-ss'.zip'");
+  static {
+    BACKUP_FILENAME_FORMAT.setTimeZone(TimeZone.getTimeZone("UTC"));
+  }
+
+  private static final String BACKUPS_SUBDIR = "backups";
+  private static final int BACKUP_FORMAT_VERSION = 1;
+  private static final String ZIP_ENTRY_NAME =
+      "backup.mytracks.v" + BACKUP_FORMAT_VERSION;
+  private static final int COMPRESSION_LEVEL = 8;
+
+  private final Context context;
+  private final FileUtils fileUtils;
+
+  public ExternalFileBackup(Context context, FileUtils fileUtils) {
+    this.context = context;
+    this.fileUtils = fileUtils;
+  }
+
+  /**
+   * Returns whether the backups directory is (or can be made) available.
+   *
+   * @param create whether to try creating the directory if it doesn't exist
+   */
+  public boolean isBackupsDirectoryAvailable(boolean create) {
+    return getBackupsDirectory(create) != null;
+  }
+
+  /**
+   * Returns the backup directory, or null if not available.
+   *
+   * @param create whether to try creating the directory if it doesn't exist
+   */
+  private File getBackupsDirectory(boolean create) {
+    String dirName = fileUtils.buildExternalDirectoryPath(BACKUPS_SUBDIR);
+    final File dir = new File(dirName);
+    Log.d(Constants.TAG, "Dir: " + dir.getAbsolutePath());
+    if (create) {
+      // Try to create - if that fails, return null
+      return fileUtils.ensureDirectoryExists(dir) ? dir : null;
+    } else {
+      // Return it if it already exists, otherwise return null
+      return dir.isDirectory() ? dir : null;
+    }
+  }
+
+  /**
+   * Returns a list of available backups to be restored.
+   */
+  public Date[] getAvailableBackups() {
+    File dir = getBackupsDirectory(false);
+    if (dir == null) { return null; }
+    String[] fileNames = dir.list();
+
+    List<Date> backupDates = new ArrayList<Date>(fileNames.length);
+    for (int i = 0; i < fileNames.length; i++) {
+      String fileName = fileNames[i];
+      try {
+        backupDates.add(BACKUP_FILENAME_FORMAT.parse(fileName));
+      } catch (ParseException e) {
+        // Not a backup file, ignore
+      }
+    }
+
+    return backupDates.toArray(new Date[backupDates.size()]);
+  }
+
+  /**
+   * Writes the backup to the default file.
+   */
+  public void writeToDefaultFile() throws IOException {
+    writeToFile(getFileForDate(new Date()));
+  }
+
+  /**
+   * Restores the backup from the given date.
+   */
+  public void restoreFromDate(Date when) throws IOException {
+    restoreFromFile(getFileForDate(when));
+  }
+
+  /**
+   * Produces the proper file descriptor for the given backup date.
+   */
+  private File getFileForDate(Date when) {
+    File dir = getBackupsDirectory(false);
+    String fileName = BACKUP_FILENAME_FORMAT.format(when);
+    File file = new File(dir, fileName);
+    return file;
+  }
+
+  /**
+   * Synchronously writes a backup to the given file.
+   */
+  private void writeToFile(File outputFile) throws IOException {
+    Log.d(Constants.TAG,
+        "Writing backup to file " + outputFile.getAbsolutePath());
+
+    // Create all the auxiliary classes that will do the writing
+    PreferenceBackupHelper preferencesHelper = new PreferenceBackupHelper();
+    DatabaseDumper trackDumper = new DatabaseDumper(
+        BackupColumns.TRACKS_BACKUP_COLUMNS,
+        BackupColumns.TRACKS_BACKUP_COLUMN_TYPES,
+        false);
+    DatabaseDumper waypointDumper = new DatabaseDumper(
+        BackupColumns.WAYPOINTS_BACKUP_COLUMNS,
+        BackupColumns.WAYPOINTS_BACKUP_COLUMN_TYPES,
+        false);
+    DatabaseDumper pointDumper = new DatabaseDumper(
+        BackupColumns.POINTS_BACKUP_COLUMNS,
+        BackupColumns.POINTS_BACKUP_COLUMN_TYPES,
+        false);
+
+    // Open the target for writing
+    FileOutputStream outputStream = new FileOutputStream(outputFile);
+    ZipOutputStream compressedStream = new ZipOutputStream(outputStream);
+    compressedStream.setLevel(COMPRESSION_LEVEL);
+    compressedStream.putNextEntry(new ZipEntry(ZIP_ENTRY_NAME));
+    DataOutputStream outWriter = new DataOutputStream(compressedStream);
+
+    try {
+      // Dump the entire contents of each table
+      ContentResolver contentResolver = context.getContentResolver();
+      Cursor tracksCursor = contentResolver.query(
+          TracksColumns.CONTENT_URI, null, null, null, null);
+      try {
+        trackDumper.writeAllRows(tracksCursor, outWriter);
+      } finally {
+        tracksCursor.close();
+      }
+
+      Cursor waypointsCursor = contentResolver.query(
+          WaypointsColumns.CONTENT_URI, null, null, null, null);
+      try {
+        waypointDumper.writeAllRows(waypointsCursor, outWriter);
+      } finally {
+        waypointsCursor.close();
+      }
+
+      Cursor pointsCursor = contentResolver.query(
+          TrackPointsColumns.CONTENT_URI, null, null, null, null);
+      try {
+        pointDumper.writeAllRows(pointsCursor, outWriter);
+      } finally {
+        pointsCursor.close();
+      }
+
+      // Dump preferences
+      SharedPreferences preferences =
+          context.getSharedPreferences(Constants.SETTINGS_NAME, 0);
+      preferencesHelper.exportPreferences(preferences, outWriter);
+    } catch (IOException e) {
+      // We tried to delete the partially created file, but do nothing
+      // if that also fails.
+      if (!outputFile.delete()) {
+        Log.w(TAG, "Failed to delete file " + outputFile.getAbsolutePath());
+      }
+
+      throw e;
+    } finally {
+      compressedStream.closeEntry();
+      compressedStream.close();
+    }
+  }
+
+  /**
+   * Synchronously restores the backup from the given file.
+   */
+  private void restoreFromFile(File inputFile) throws IOException {
+    Log.d(Constants.TAG,
+        "Restoring from file " + inputFile.getAbsolutePath());
+
+    PreferenceBackupHelper preferencesHelper = new PreferenceBackupHelper();
+    ContentResolver resolver = context.getContentResolver();
+    DatabaseImporter trackImporter =
+        new DatabaseImporter(TracksColumns.CONTENT_URI, resolver, false);
+    DatabaseImporter waypointImporter =
+        new DatabaseImporter(WaypointsColumns.CONTENT_URI, resolver, false);
+    DatabaseImporter pointImporter =
+        new DatabaseImporter(TrackPointsColumns.CONTENT_URI, resolver, false);
+
+    ZipFile zipFile = new ZipFile(inputFile, ZipFile.OPEN_READ);
+    ZipEntry zipEntry = zipFile.getEntry(ZIP_ENTRY_NAME);
+    if (zipEntry == null) {
+      throw new IOException("Invalid backup ZIP file");
+    }
+
+    InputStream compressedStream = zipFile.getInputStream(zipEntry);
+    DataInputStream reader = new DataInputStream(compressedStream);
+
+    try {
+      // Delete all previous contents of the tables and preferences.
+      resolver.delete(TracksColumns.CONTENT_URI, null, null);
+      resolver.delete(TrackPointsColumns.CONTENT_URI, null, null);
+      resolver.delete(WaypointsColumns.CONTENT_URI, null, null);
+
+      // Import the new contents of each table
+      trackImporter.importAllRows(reader);
+      waypointImporter.importAllRows(reader);
+      pointImporter.importAllRows(reader);
+
+      // Restore preferences
+      SharedPreferences preferences =
+          context.getSharedPreferences(Constants.SETTINGS_NAME, 0);
+      preferencesHelper.importPreferences(reader, preferences);
+    } finally {
+      compressedStream.close();
+      zipFile.close();
+    }
+  }
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/MyTracksBackupAgent.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import com.google.android.apps.mytracks.Constants;
+
+import android.app.backup.BackupAgent;
+import android.app.backup.BackupDataInput;
+import android.app.backup.BackupDataOutput;
+import android.content.SharedPreferences;
+import android.os.ParcelFileDescriptor;
+import android.util.Log;
+
+import java.io.IOException;
+
+/**
+ * Backup agent used to backup and restore all preferences.
+ * We use a regular {@link BackupAgent} instead of the convenient helpers in
+ * order to be future-proof (assuming we'll want to back up tracks later).
+ * 
+ * @author Rodrigo Damazio
+ */
+public class MyTracksBackupAgent extends BackupAgent {
+  private static final String PREFERENCES_ENTITY = "prefs";
+
+  @Override
+  public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
+      ParcelFileDescriptor newState) throws IOException {
+    Log.i(Constants.TAG, "Performing backup");
+    SharedPreferences preferences = this.getSharedPreferences(
+        Constants.SETTINGS_NAME, 0);
+
+    backupPreferences(data, preferences);
+    Log.i(Constants.TAG, "Backup complete");
+  }
+
+  private void backupPreferences(BackupDataOutput data,
+      SharedPreferences preferences) throws IOException {
+    PreferenceBackupHelper preferenceDumper = createPreferenceBackupHelper();
+    byte[] dumpedContents = preferenceDumper.exportPreferences(preferences);
+    data.writeEntityHeader(PREFERENCES_ENTITY, dumpedContents.length);
+    data.writeEntityData(dumpedContents, dumpedContents.length);
+  }
+
+  protected PreferenceBackupHelper createPreferenceBackupHelper() {
+    return new PreferenceBackupHelper();
+  }
+
+  @Override
+  public void onRestore(BackupDataInput data, int appVersionCode,
+      ParcelFileDescriptor newState) throws IOException {
+    Log.i(Constants.TAG, "Restoring from backup");
+    while (data.readNextHeader()) {
+      String key = data.getKey();
+      Log.d(Constants.TAG, "Restoring entity " + key);
+      if (key.equals(PREFERENCES_ENTITY)) {
+        restorePreferences(data);
+      } else {
+        Log.e(Constants.TAG, "Found unknown backup entity: " + key);
+        data.skipEntityData();
+      }
+    }
+    Log.i(Constants.TAG, "Done restoring from backup");
+  }
+
+  /**
+   * Restores all preferences from the backup.
+   * 
+   * @param data the backup data to read from
+   * @throws IOException if there are any errors while reading
+   */
+  private void restorePreferences(BackupDataInput data) throws IOException {
+    int dataSize = data.getDataSize();
+    byte[] dataBuffer = new byte[dataSize];
+    int read = data.readEntityData(dataBuffer, 0, dataSize);
+    if (read != dataSize) {
+      throw new IOException("Failed to read all the preferences data");
+    }
+
+    SharedPreferences preferences = this.getSharedPreferences(
+        Constants.SETTINGS_NAME, 0);
+    PreferenceBackupHelper importer = createPreferenceBackupHelper();
+    importer.importPreferences(dataBuffer, preferences);
+  }
+}

MyTracks/src/com/google/android/apps/mytracks/io/backup/PreferenceBackupHelper.java

@@ -0,0 +1,176 @@
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * 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.google.android.apps.mytracks.io.backup;
+
+import com.google.android.apps.mytracks.content.ContentTypeIds;
+
+import android.content.SharedPreferences;
+import android.content.SharedPreferences.Editor;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ * Helper for backing up and restoring shared preferences.
+ *
+ * @author Rodrigo Damazio
+ */
+class PreferenceBackupHelper {
+
+  private static final int BUFFER_SIZE = 2048;
+
+  /**
+   * Exports all shared preferences from the given object as a byte array.
+   *
+   * @param preferences the preferences to export
+   * @return the corresponding byte array
+   * @throws IOException if there are any errors while writing to the byte array
+   */
+  public byte[] exportPreferences(SharedPreferences preferences)
+      throws IOException {
+    ByteArrayOutputStream bufStream = new ByteArrayOutputStream(BUFFER_SIZE);
+    DataOutputStream outWriter = new DataOutputStream(bufStream);
+    exportPreferences(preferences, outWriter);
+
+    return bufStream.toByteArray();
+  }
+
+  /**
+   * Exports all shared preferences from the given object into the given output
+   * stream.
+   *
+   * @param preferences the preferences to export
+   * @param outWriter the stream to write them to
+   * @throws IOException if there are any errors while writing the output
+   */
+  public void exportPreferences(
+      SharedPreferences preferences,
+      DataOutputStream outWriter) throws IOException {
+    Map<String, ?> values = preferences.getAll();
+
+    outWriter.writeInt(values.size());
+    for (Map.Entry<String, ?> entry : values.entrySet()) {
+      writePreference(entry.getKey(), entry.getValue(), outWriter);
+    }
+    outWriter.flush();
+  }
+
+  /**
+   * Imports all preferences from the given byte array.
+   *
+   * @param data the byte array to read preferences from
+   * @param preferences the shared preferences to edit
+   * @return whether the preference change was successful
+   * @throws IOException if there are any errors while reading
+   */
+  public boolean importPreferences(byte[] data, SharedPreferences preferences)
+      throws IOException {
+    ByteArrayInputStream bufStream = new ByteArrayInputStream(data);
+    DataInputStream reader = new DataInputStream(bufStream);
+
+    return importPreferences(reader, preferences);
+  }
+
+  /**
+   * Imports all preferences from the given stream.
+   *
+   * @param reader the stream to read from
+   * @param preferences the shared preferences to edit
+   * @return whether the preference change was successful
+   * @throws IOException if there are any errors while reading
+   */
+  public boolean importPreferences(DataInputStream reader,
+      SharedPreferences preferences) throws IOException {
+    Editor editor = preferences.edit();
+    editor.clear();
+
+    int numPreferences = reader.readInt();
+    for (int i = 0; i < numPreferences; i++) {
+      String name = reader.readUTF();
+      byte typeId = reader.readByte();
+      readAndSetPreference(name, typeId, reader, editor);
+    }
+
+    return editor.commit();
+  }
+
+  /**
+   * Reads a single preference and sets it into the given editor.
+   *
+   * @param name the name of the preference to read
+   * @param typeId the type ID of the preference to read
+   * @param reader the reader to read from
+   * @param editor the editor to set the preference in
+   * @throws IOException if there are errors while reading
+   */
+  private void readAndSetPreference(String name, byte typeId,
+      DataInputStream reader, Editor editor) throws IOException {
+    switch (typeId) {
+      case ContentTypeIds.BOOLEAN_TYPE_ID:
+        editor.putBoolean(name, reader.readBoolean());
+        return;
+      case ContentTypeIds.LONG_TYPE_ID:
+        editor.putLong(name, reader.readLong());
+        return;
+      case ContentTypeIds.FLOAT_TYPE_ID:
+        editor.putFloat(name, reader.readFloat());
+        return;
+      case ContentTypeIds.INT_TYPE_ID:
+        editor.putInt(name, reader.readInt());
+        return;
+      case ContentTypeIds.STRING_TYPE_ID:
+        editor.putString(name, reader.readUTF());
+        return;
+    }
+  }
+
+  /**
+   * Writes a single preference.
+   *
+   * @param name the name of the preference to write
+   * @param value the correctly-typed value of the preference
+   * @param writer the writer to write to
+   * @throws IOException if there are errors while writing
+   */
+  private void writePreference(String name, Object value, DataOutputStream writer)
+      throws IOException {
+    writer.writeUTF(name);
+
+    if (value instanceof Boolean) {
+      writer.writeByte(ContentTypeIds.BOOLEAN_TYPE_ID);
+      writer.writeBoolean((Boolean) value);
+    } else if (value instanceof Integer) {
+      writer.writeByte(ContentTypeIds.INT_TYPE_ID);
+      writer.writeInt((Integer) value);
+    } else if (value instanceof Long) {
+      writer.writeByte(ContentTypeIds.LONG_TYPE_ID);
+      writer.writeLong((Long) value);
+    } else if (value instanceof Float) {
+      writer.writeByte(ContentTypeIds.FLOAT_TYPE_ID);
+      writer.writeFloat((Float) value);
+    } else if (value instanceof String) {
+      writer.writeByte(ContentTypeIds.STRING_TYPE_ID);
+      writer.writeUTF((String) value);
+    } else {
+      throw new IllegalArgumentException(
+          "Type " + value.getClass().getName() + " not supported");
+    }
+  }
+}