Create just one Button and add something like a buttonstatus. Then you can check the status in your listener.
For example:
boolean isPlaying = false;
playPause = (Button) findViewById(R.id.play);
playPause.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if (isPlaying) {
pause();
}else{
play();
}
isPlaying = !isPlaying;
}
});