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* <td class="DescrColumn">The Save/Restore Screen implementation * </tr> * <tr> * <td class="LinkColumn">/res/any/layout/save_restore_state.xml * <td class="DescrColumn">Defines contents of the screen * </tr> * </table> * */ public class PersistentState extends Activity { /** * Initialization of the Activity after it is first created. Here we use * {@link android.app.Activity#setContentView setContentView()} to set up * the Activity's content, and retrieve the EditText widget whose state we * will persistent. */ @Override protected void onCreate(Bundle savedInstanceState) { // Be sure to call the super class. super.onCreate(savedInstanceState); // See assets/res/any/layout/save_restore_state.xml for this // view layout definition, which is being set here as // the content of our screen. setContentView(R.layout.save_restore_state); // Set message to be appropriate for this screen. ((TextView)findViewById(R.id.msg)).setText(R.string.persistent_msg); // Retrieve the EditText widget whose state we will save. mSaved = (EditText)findViewById(R.id.saved); } /** * Upon being resumed we can retrieve the current state. This allows us * to update the state if it was changed at any time while paused. */ @Override protected void onResume() { super.onResume(); SharedPreferences prefs = getPreferences(0); String restoredText = prefs.getString("text", null); if (restoredText != null) { mSaved.setText(restoredText, TextView.BufferType.EDITABLE); int selectionStart = prefs.getInt("selection-start", -1); int selectionEnd = prefs.getInt("selection-end", -1); if (selectionStart != -1 && selectionEnd != -1) { mSaved.setSelection(selectionStart, selectionEnd); } } } /** * Any time we are paused we need to save away the current state, so it * will be restored correctly when we are resumed. */ @Override protected void onPause() { super.onPause(); SharedPreferences.Editor editor = getPreferences(0).edit(); editor.putString("text", mSaved.getText().toString()); editor.putInt("selection-start", mSaved.getSelectionStart()); editor.putInt("selection-end", mSaved.getSelectionEnd()); editor.commit(); } private EditText mSaved; }

Other Android examples (source code examples)

Here is a short list of links related to this Android PersistentState.java source code file:

Android example source code file (PersistentState.java)

This example Android source code file (PersistentState.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

activity, android, app, content, edittext, os, override, persistentstate, sharedpreferences, string, ui, widget

The PersistentState.java Android example source code

/*
 * Copyright (C) 2007 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.example.android.apis.app;

// Need the following import to get access to the app resources, since this
// class is in a sub-package.

import com.example.android.apis.R;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.TextView;

/**
 * Simple example of using persistent preferences to retain a screen's state.
 * <p>This can be used as an alternative to the normal
 * <code>onSaveInstanceState() mechanism, if you
 * wish the state to persist even after an activity is finished.</p>
 *
 * <p>Note that using this approach requires more care, since you are sharing
 * the persistent state potentially across multiple instances of the activity.
 * In particular, if you allow a new instance of the activity to be launched
 * directly on top of the existing instance, the state can get out of sync
 * because the new instance is resumed before the old one is paused.</p>
 *
 * <p>For any persistent state that is not simplistic, a content
 * provider is often a better choice.</p>
 *
 * <p>In this example we are currently saving and restoring the state of the
 * top text editor, but not of the bottom text editor.  You can see the difference
 * by editing the two text fields, then going back from the activity and
 * starting it again.</p>
 *
 * <h4>Demo
 * App/Activity/Save & Restore State
 *
 * <h4>Source files
 * <table class="LinkTable">
 *         <tr>
 *             <td class="LinkColumn">src/com.example.android.apis/app/PersistentState.java
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