public void onClick(View v) {
        if (v == B_start) {  // 시작버튼 클릭
                     생략
        }
        else {
            if(chk != 3)
            {
                switch (v.getId()) {
                    case R.id.btn1:
                        CK_num[chk] = Integer.parseInt(((Button) v).getText().toString());
                        break;
                    case R.id.btn2:
                        CK_num[chk] = Integer.parseInt(((Button) v).getText().toString());
                        break;
                    case R.id.btn3:
                        CK_num[chk] = Integer.parseInt(((Button) v).getText().toString());
                        break;
                    case R.id.btn4:
                        CK_num[chk] = Integer.parseInt(((Button) v).getText().toString());
                        break;
                    case R.id.btn5:
                        CK_num[chk] = Integer.parseInt(((Button) v).getText().toString());
                        break;
                    case R.id.btn6:
                        CK_num[chk] = Integer.parseInt(((Button) v).getText().toString());
                        break;
                }
                chk++;
            }
            if (chk == 3) {
                C_cnt = CAcheck(CK_num);     // 맞은 개수 확인
                if (C_cnt == 0)                    // 정답 개수만큼 점수++
                    G_score += 0;
                else if (C_cnt == 1)
                    G_score += 1;
                else if (C_cnt == 2)
                    G_score += 3;
                else if (C_cnt == 3)
                    G_score += 5;
                G_round++;
                T_score.setText("" + G_score);
                T_round.setText("" + G_round);
                chk = 0;
            }
    }
}
 
버튼 3개 누른다음에 한번에 처리해서 점수 +하려고 하는데
각 버튼을 최대 1번씩만 누르게 하는 방법은 뭐가 있나요?
그 버튼 숨기는 invisivle 이거 말고는 없나요?