JPanel btnPanel = new JPanel();
                        btnPanel.setLayout(new GridLayout(5, 5));
                        JButton[][] buttonArray = new JButton[4][4];
                        for (int i = 0; i < 5; i++) {
                                  for (int j = 0; j <5; j++) {
                                        buttonArray[i][j] = new JButton();
                                        btnPanel.add(buttonArray[i][j]);
                                  }
                        }

버튼배열 이런식으로 만드는거 아니냐??

왜 실행하면 

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
        at bingo.<init>(bingo.java:69)
        at bingo.main(bingo.java:178)


이렇게 뜨는거지???
        buttonArray[i][j] = new JButton();
이부분에서 익셉션 발생한다는데 ㅜㅜ 뭐가 문제죠 횽들