我正在制作一个3x3网格类型的应用程序，我想通过添加for循环来调用按下的按钮来更改它。但是，我得到了异常“java.lang.arrayindexoutofboundsexception:length=3；索引=3“，因为for循环很奇怪。有人能帮我弄明白吗？我对java和编程都是新手。
代码：

public int j = 1;
public int i = 1;
public final int[][] buttons = new int[][] {
        {R.id.top_left_button, R.id.top_center_button, R.id.top_right_button},
        {R.id.left_button, R.id.center_button, R.id.right_button},
        {R.id.bottom_left_button, R.id.bottom_center_button, R.id.bottom_right_button}};
private Button lastButton;

public void setPlayer(Button button, int x, int y){
    button.setText("!");
    lastButton = (Button)findViewById(buttons[x][y]);
    lastButton.setText(" ");
    lastButton = button;
}
@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_game);

    ctx = this;

    final GameEngine game = new GameEngine();
    lastButton = (Button)findViewById(R.id.center_button);
    for (i = 0; i < buttons.length; i++) {
        for (j = 0; j < buttons[i].length; j++) {
            final Button button = (Button)findViewById(buttons[i][j]);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Button b = (Button)v;
                    int x = i;
                    int y = j;
                    setPlayer(b, x , y);
                }
            });
        }
    }