Trocar String Por Imagem android studio

Programação
#1

OLá gostaria de trocar a string pela imagem no meu programa, consegui colocar a imagem, mas a string ainda está lá:

private void highlightCurrentPlayer() {
if (currentPlayer == PLAYER_ONE) {
playerOneTextView.setTypeface(null, Typeface.BOLD);
playerTwoTextView.setTypeface(null, Typeface.NORMAL);
} else if (currentPlayer == PLAYER_TWO) {
playerOneTextView.setTypeface(null, Typeface.NORMAL);
playerTwoTextView.setTypeface(null, Typeface.BOLD);
}
}

private void setButtonMarker(Button button) {
    if (TextUtils.isEmpty(button.getText().toString())) {
        button.setText(MARKER_CELL[currentPlayer]);

        if (currentPlayer == PLAYER_ONE)
            button.setBackground(getResources().getDrawable(R.drawable.captainamerica, getTheme()));
        else if (currentPlayer == PLAYER_TWO)
            button.setBackground(getResources().getDrawable(R.drawable.ironman, getTheme()));

        playNumbers++;

        checkWinner();

        currentPlayer = ++currentPlayer % 2;

        highlightCurrentPlayer();
    }

fiz isso e saiu a imagem

private void setButtonMarker(Button button) {
if (TextUtils.isEmpty(button.getText().toString())) {
button.setText(MARKER_CELL[currentPlayer]);

        if (currentPlayer == PLAYER_ONE)
            button.setBackground(getResources().getDrawable(R.drawable.captainamerica, getTheme()));
        else if (currentPlayer == PLAYER_TWO)
            button.setBackground(getResources().getDrawable(R.drawable.ironman, getTheme()));

        playNumbers++;

        checkWinner();

        currentPlayer = ++currentPlayer % 2;

        highlightCurrentPlayer();
    }