ImageView X axis don't update in Thread

Issue

I'm trying to animate an object coming down from an ImageView but the ImageView's X-axis doesn't update while moving.

Here is the Thread:

public class EnemyMoveThread extends Thread // Enemy animation
{
    @Override
    public void run()
    {
        **enemyX = enemy.getX();** // this is the problematic part

        while (! disqualified())
        {
            try {
                enemy.startAnimation(ltrAnim); // move ImageView left to right


                Thread.sleep(600);
            }
            catch (InterruptedException e) 
            {    e.printStackTrace();    }

            try {
                enemy.startAnimation(rtlAnim); // move ImageView left to right


                Thread.sleep(600);
            }
            catch (InterruptedException e)
            {    e.printStackTrace();    }
        }

    }
}

Solution

That's because the Thread can't update gui elements, as it isn't the main thread. However the Activity provides a method called runOnUiThread(Runnable runnable), that can update GUI elements. In your code you would need to get the Activity of your app, using a custom constructor and then call the GUI update methods using

activity.runOnUiThread(() -> {
    // your GUI code here
});

Answered By - Sebastian