Java Activity.onBackPressed方法代碼示例

import android.app.Activity; //導入方法依賴的package包/類
public void onBackPressed() {
    Activity activity = getActivity();

    if (activity != null) {
        activity.onBackPressed();
    }
}
 

import android.app.Activity; //導入方法依賴的package包/類
/**
 * This utility method handles Up navigation intents by searching for a parent activity and
 * navigating there if defined. When using this for an activity make sure to define both the
 * native parentActivity as well as the AppCompat one when supporting API levels less than 16.
 * when the activity has a single parent activity. If the activity doesn't have a single parent
 * activity then don't define one and this method will use back button functionality. If "Up"
 * functionality is still desired for activities without parents then use
 * {@code syntheticParentActivity} to define one dynamically.
 *
 * Note: Up navigation intents are represented by a back arrow in the top left of the Toolbar
 *       in Material Design guidelines.
 *
 * @param currentActivity Activity in use when navigate Up action occurred.
 * @param syntheticParentActivity Parent activity to use when one is not already configured.
 */
public static void navigateUpOrBack(Activity currentActivity,
                                    Class<? extends Activity> syntheticParentActivity) {
    // Retrieve parent activity from AndroidManifest.
    Intent intent = NavUtils.getParentActivityIntent(currentActivity);

    // Synthesize the parent activity when a natural one doesn't exist.
    if (intent == null && syntheticParentActivity != null) {
        try {
            intent = NavUtils.getParentActivityIntent(currentActivity, syntheticParentActivity);
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
    }

    if (intent == null) {
        // No parent defined in manifest. This indicates the activity may be used by
        // in multiple flows throughout the app and doesn't have a strict parent. In
        // this case the navigation up button should act in the same manner as the
        // back button. This will result in users being forwarded back to other
        // applications if currentActivity was invoked from another application.
        currentActivity.onBackPressed();
    } else {
        if (NavUtils.shouldUpRecreateTask(currentActivity, intent)) {
            // Need to synthesize a backstack since currentActivity was probably invoked by a
            // different app. The preserves the "Up" functionality within the app according to
            // the activity hierarchy defined in AndroidManifest.xml via parentActivity
            // attributes.
            TaskStackBuilder builder = TaskStackBuilder.create(currentActivity);
            builder.addNextIntentWithParentStack(intent);
            builder.startActivities();
        } else {
            // Navigate normally to the manifest defined "Up" activity.
            NavUtils.navigateUpTo(currentActivity, intent);
        }
    }
}