Problems with jumping animation

I made a jumping animation but when i stop touching the screen, the animation stops.

Here is the code:

    boolean touching = Gdx.input.isTouched();
    long elapsed = (System.currentTimeMillis() - startTime)%1000;

    if (touching){
        float jump = 500 * (float)Math.sin(((Math.PI*2)/1000)*(elapsed/2));
        sprite.setPosition(Gdx.graphics.getWidth()/2,jump);
    }

How do i make the animation finish after i stop touching the screen?

Here is a gif of the code running:

I think what you want to achieve is to jump by a single touch and let it finish. I would use somekind of state to do this. Currently, the code within your statement only runs when touching.

Whenever a user touches the screen you could set a boolean jumping to true. Then instead of checking if (touching) you check for if (jumping). Here you put the code for the jump. When someone presses the screen while jumping you should not allow it to reset (except in the case of something like a double jump). And whenever the entity touches the ground again jumping should be set back to false.