Demonstrates required behavior of saving and restoring dynamic activity state : Activity « UI « Android

1. Android
2. UI
3. Activity

Demonstrates required behavior of saving and restoring dynamic activity state

     

 
/*
 * 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 app.test;

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

/**
 * <p>Demonstrates required behavior of saving and restoring dynamic activity
 * state, so that an activity will restart with the correct state if it is
 * stopped by the system.</p>
 *
 * <p>In general, any activity that has been paused may be stopped by the system
 * at any time if it needs more resources for the currently running activity.
 * To handle this, before being paused the
 * {@link android.app.Activity#onSaveInstanceState onSaveInstanceState()} method is called before
 * an activity is paused, allowing it to supply its current state.  If that
 * activity then needs to be stopped, upon restarting it will receive its
 * last saved state in
 * {@link android.app.Activity#onCreate}.</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 to a couple different
 * applications while the demo is running and then returning back to it.  The
 * system takes care of saving a view's state as long as an id has been
 * assigned to the view, so we assign an ID to the view being saved but not
 * one to the view that isn't being saved.</p>
 * <h4>Demo</h4>
 * App/Activity/Save &amp; Restore State
 * <h4>Source files</h4>
 * <table class="LinkTable">
        <tr>
            <td class="LinkColumn">src/com.example.android.apis/app/SaveRestoreState.java</td>
            <td class="DescrColumn">The Save/Restore Screen implementation</td>
        </tr>
        <tr>
            <td class="LinkColumn">/res/any/layout/save_restore_state.xml</td>
            <td class="DescrColumn">Defines contents of the screen</td>
        </tr>
</table>
 */
public class SaveRestoreState 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 save/restore.
     */
    @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.main);

        // Set message to be appropriate for this screen.
        ((TextView)findViewById(R.id.msg)).setText("save_restore_msg");
    }

    /**
     * Retrieve the text that is currently in the "saved" editor.
     */
    CharSequence getSavedText() {
        return ((EditText)findViewById(R.id.saved)).getText();
    }

    /**
     * Change the text that is currently in the "saved" editor.
     */
    void setSavedText(CharSequence text) {
        ((EditText)findViewById(R.id.saved)).setText(text);
    }
}

//main.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- 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.
-->

<!-- Demonstrates saving and restoring activity state.
     See corresponding Java code com.android.sdk.app.SaveRestoreState.java. -->

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent">
    <LinearLayout android:orientation="vertical" android:padding="4dip"
        android:layout_width="match_parent" android:layout_height="wrap_content">

        <TextView android:id="@+id/msg"
            android:layout_width="match_parent" android:layout_height="wrap_content"
            android:layout_weight="0" android:textAppearance="?android:attr/textAppearanceMedium"
            android:paddingBottom="4dip" />

        <TextView
            android:layout_width="match_parent" android:layout_height="wrap_content"
            android:layout_weight="0" android:paddingBottom="4dip"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="saves_state"/>

        <EditText android:id="@+id/saved"
            android:layout_width="match_parent" android:layout_height="wrap_content"
            android:layout_weight="1" android:background="@drawable/icon"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="initial_text"
            android:freezesText="true">
        </EditText>

        <TextView
            android:layout_width="match_parent" android:layout_height="wrap_content"
            android:layout_weight="0" android:paddingTop="8dip" 
            android:paddingBottom="4dip"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="no_saves_state"/>

        <EditText
            android:layout_width="match_parent" android:layout_height="wrap_content"
            android:layout_weight="1" android:background="@drawable/icon"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="initial_text">
        </EditText>

    </LinearLayout>
</ScrollView>

   
    
    
    
    
  

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