cancelling a handler.postdelayed process

Question

I am using handler.postDelayed() to create a waiting period before the next stage of my app takes place. During the wait period I am displaying a dialog with progress bar and cancel button.

My problem is I can't find a way to cancel the postDelayed task before the time elapses.

Answer 1

Here is a class providing a cancel method for a delayed action

public class DelayedAction {

private Handler _handler;
private Runnable _runnable;

/**
 * Constructor
 * @param runnable The runnable
 * @param delay The delay (in milli sec) to wait before running the runnable
 */
public DelayedAction(Runnable runnable, long delay) {
    _handler = new Handler(Looper.getMainLooper());
    _runnable = runnable;
    _handler.postDelayed(_runnable, delay);
}

/**
 * Cancel a runnable
 */
public void cancel() {
    if ( _handler == null || _runnable == null ) {
        return;
    }
    _handler.removeCallbacks(_runnable);
}}

Answer 2

I do this to post a delayed runnable:

myHandler.postDelayed(myRunnable, SPLASH_DISPLAY_LENGTH); 

And this to remove it: myHandler.removeCallbacks(myRunnable);

Answer 3

It worked for me when I called CancelCallBacks(this) inside the post delayed runnable by handing it via a boolean

Runnable runnable = new Runnable(){
    @Override
    public void run() {
        Log.e("HANDLER", "run: Outside Runnable");
        if (IsRecording) {
            Log.e("HANDLER", "run: Runnable");
            handler.postDelayed(this, 2000);
        }else{
            handler.removeCallbacks(this);
        }
    }
};

Answer 4

Hope this gist help https://gist.github.com/imammubin/a587192982ff8db221da14d094df6fb4

MainActivity as Screen Launcher with handler & runnable function, the Runnable run to login page or feed page with base preference login user with firebase.

Answer 5

Another way is to handle the Runnable itself:

Runnable r = new Runnable {
    public void run() {
        if (booleanCancelMember != false) {
            //do what you need
        }
    }
}

Answer 6

In case you do have multiple inner/anonymous runnables passed to same handler, and you want to cancel all at same event use

handler.removeCallbacksAndMessages(null);

As per documentation,

Remove any pending posts of callbacks and sent messages whose obj is token. If token is null, all callbacks and messages will be removed.