JMenuItem和ActionListener

Question

我的JMenuItem和ActionListener有问题，我正在尝试制作一个JMenuItem，它可以选择游戏中的玩家数量，但我的PlayerAlt[i].addActionListener(players);代码给了我一个错误，即“玩家不能被解析为变量”

    String[] Players = { "1", "2", "3", "4" };
    JMenu pmenu = new JMenu("Players");
    final JMenuItem[] PlayerAlt = new JMenuItem[Players.length];
    for (int i = 0; i < PlayerAlt.length; i++) {
      PlayerAlt[i] = new JMenuItem(Players[i]);
      pmenu.add(PlayerAlt[i]);
      PlayerAlt[i].addActionListener(players);
    }
    ActionListener players = new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        for (int i = 0; i < PlayerAlt.length; i++) {
          if (e.getSource() == PlayerAlt[i]) {
        Gamerside.add(s1);
          }
        }
      }
    };

Answer 1

变量players是在您想使用它之后声明的。因此，这是无法解决的。

将players声明移至循环上方

ActionListener players = new ActionListener() {
      ......
};
for (int i = 0; i < PlayerAlt.length; i++) {
    .....
    PlayerAlt[i].addActionListener(players);
}

Answer 2

在您的示例中，players在尝试使用它之后被声明为(在两行之后)，所以在尝试使用它的时候它是不存在的。

为求澄清：

int b = 4;
b += a; //Error, a does not exist yet..
int a = 2; //...because it is declared here