Clear Arrays without List

I am trying to create a small project in Android Studio (through Java) and have met some issues, one is to try and clear two float-type arrays, another is that a button, that should jump to a random (out of 9 places) location on screen, is staying in same position, here is the code.

My goal is to make the button jump to a random location on the screen (X and Y axis positions are written in randArgsX and randArgsY arrays) without staying in the same place after a click.

An extra thing that would be thanked is to add a timer till the button disappears after reappearing, and if the player taps a wrong place (outside a small radius of about 20 px) or the time until the button disappeared is up, the player will lose 1 life.