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SaveRestoreState.javaAPI DocGoogle Android v1.5 Example4616Sun Nov 11 13:01:04 GMT 2007com.google.android.samples.app

SaveRestoreState

public class SaveRestoreState extends android.app.Activity

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.

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#onFreeze onFreeze()} 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}.

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.

Demo

App/Activity/Save & Restore State

Source files

src/com/google/android/samples/app/SaveRestoreState.java The Save/Restore Screen implementation
/res/any/layout/save_restore_state.xml Defines contents of the screen

Fields Summary
private android.widget.EditText
mSaved
Constructors Summary
Methods Summary
java.lang.CharSequencegetSavedText()
Retrieve the text that is currently in the "saved" editor.

        return ((EditText)findViewById(R.id.saved)).getText();
protected voidonCreate(android.os.Bundle icicle)
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.

        // Be sure to call the super class.
        super.onCreate(icicle);

        // 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.save_restore_msg);

        // Retrieve the EditText widget whose state we will save.
        mSaved = (EditText)findViewById(R.id.saved);

        // Look for any previously saved state of the EditText.
        Bundle textState = icicle != null ? icicle.getBundle("text") : null;
        if (textState != null) {
            // Have the widget restore its previously save state.  If we
            // didn't find any state, we will skip this and thus use the
            // default string in the EditText.
            mSaved.restoreState(textState);
        }
protected voidonFreeze(android.os.Bundle outState)
This is where you can save your current state. It is called immediately before onStop().

param
outState Map in which to place your state.

        super.onFreeze(outState);

        // Save the current text editor state.
        outState.putBundle("text", mSaved.saveStateAndText());
voidsetSavedText(java.lang.CharSequence text)
Change the text that is currently in the "saved" editor.

        ((EditText)findViewById(R.id.saved)).setText(text);