Loop between two images

Question

I want to loop between two images continuously. The first image should be replaced by the second image and the second by the first infinitely.

The code that I have so far is as follows:

imageHandler = new Handler();
    imageHandler.postDelayed(new Runnable() {
        @Override
        public void run() {
            Picasso.with(TokenActivity.this).load(R.drawable.app_icon).into(iconImageView);
        }
    }, 1000);
    imageHandler.postDelayed(new Runnable() {
        @Override
        public void run() {
            Picasso.with(TokenActivity.this).load(R.drawable.camera_icon).into(iconImageView);
        }
    }, 2000);

Here the flip is happening but only once. How do I program it so that it can repeat infinitely?

Answer 1

Declare two runnable :

Runnable goToImage2;
Runnable goToImage1 = new Runnable() {
  @Override
  public void run() {
   Picasso.with(TokenActivity.this).load(R.drawable.app_icon).into(iconImageView);
  handler.postDelayed(goToImage2, 2000);
  }
}
goToImage2 = new Runnable() {
  @Override
  public void run() {
   Picasso.with(TokenActivity.this).load(R.drawable.camera_icon).into(iconImageView);
  handler.postDelayed(goToImage1, 2000);
  }
}

Then simply launch the first one :

handler.postDelayed(goToImage1, 0);

EDIT : If you only need two images, you can also simply use a boolean to know which one to display, and therefore only use one runnable :

boolean isShowingFirst = true;

Runnable changeImage = new Runnable() {
  @Override
  public void run() {
   Picasso.with(TokenActivity.this).load(isShowingFirst ? R.drawable.camera_icon : R.drawable.app_icon).into(iconImageView);
  isShowingFirst = !isShowingFirst;
  handler.postDelayed(changeImage, 2000);
  }
}

And launch it with :

handler.postDelayed(changeImage, 0);