Using the Application Class
Depending on what you're doing in your initialization you could consider creating a new class that extends Application
and moving your initialization code into an overridden onCreate
method within that class.
public class MyApplicationClass extends Application {
@Override
public void onCreate() {
super.onCreate();
// TODO Put your application initialization code here.
}
}
The onCreate
in the application class is only called when the entire application is created, so the Activity restarts on orientation or keyboard visibility changes won't trigger it.
It's good practice to expose the instance of this class as a singleton and exposing the application variables you're initializing using getters and setters.
NOTE: You'll need to specify the name of your new Application class in the manifest for it to be registered and used:
<application
android:name="com.you.yourapp.MyApplicationClass"
Reacting to Configuration Changes [UPDATE: this is deprecated since API 13; see the recommended alternative]
As a further alternative, you can have your application listen for events that would cause a restart – like orientation and keyboard visibility changes – and handle them within your Activity.
Start by adding the android:configChanges
node to your Activity's manifest node
<activity android:name=".MyActivity"
android:configChanges="orientation|keyboardHidden"
android:label="@string/app_name">
or for Android 3.2 (API level 13) and newer:
<activity android:name=".MyActivity"
android:configChanges="keyboardHidden|orientation|screenSize"
android:label="@string/app_name">
Then within the Activity override the onConfigurationChanged
method and call setContentView
to force the GUI layout to be re-done in the new orientation.
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
setContentView(R.layout.myLayout);
}
Thanks to Code Shogun, whose code I adapted to my situation.
Let your activity implementOnClickListener
as usual:
public class SelectFilterActivity extends Activity implements OnClickListener {
private static final int SWIPE_MIN_DISTANCE = 120;
private static final int SWIPE_MAX_OFF_PATH = 250;
private static final int SWIPE_THRESHOLD_VELOCITY = 200;
private GestureDetector gestureDetector;
View.OnTouchListener gestureListener;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/* ... */
// Gesture detection
gestureDetector = new GestureDetector(this, new MyGestureDetector());
gestureListener = new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
};
}
class MyGestureDetector extends SimpleOnGestureListener {
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
try {
if (Math.abs(e1.getY() - e2.getY()) > SWIPE_MAX_OFF_PATH)
return false;
// right to left swipe
if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
Toast.makeText(SelectFilterActivity.this, "Left Swipe", Toast.LENGTH_SHORT).show();
} else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
Toast.makeText(SelectFilterActivity.this, "Right Swipe", Toast.LENGTH_SHORT).show();
}
} catch (Exception e) {
// nothing
}
return false;
}
@Override
public boolean onDown(MotionEvent e) {
return true;
}
}
}
Attach your gesture listener to all the views you add to the main layout;
// Do this for each view added to the grid
imageView.setOnClickListener(SelectFilterActivity.this);
imageView.setOnTouchListener(gestureListener);
Watch in awe as your overridden methods are hit, both the onClick(View v)
of the activity and the onFling
of the gesture listener.
public void onClick(View v) {
Filter f = (Filter) v.getTag();
FilterFullscreenActivity.show(this, input, f);
}
The post 'fling' dance is optional but encouraged.
Best Answer
Call
clearAnimation()
on whicheverView
you calledstartAnimation()
.