按下退出按钮时的事件：JOptionPane.showInputDialog

Question

点击取消或退出按钮后如何添加功能？我试过这样，但它对我不起作用。

它向我显示了一个错误，即选择为空，但它不可能是因为它是 int？有没有其他办法解决？

public void start() {
        
        int choice = Integer.parseInt(JOptionPane.showInputDialog(null, "Choice: \n 1 - Play a game \n 2 - show all games \n 3 - Find the best score \n 4 - Find a player \n 5 - End"));
        //if (choice == JOptionPane.OK_OPTION) {
            switch (choice) {
                case 1:
                    this.play();
                    break;
                case 2:
                    this.allGames();
                    break;
                case 3:
                    this.getBestScore();
                    break;
                case 4:
                    this.getPlayer();
                    break;
                case 5:
                    System.exit(0);
                    break;
                default:
                    JOptionPane.showMessageDialog(null, "Wrong input.");
                    break;
            }
        // } else if (choice == JOptionPane.CANCEL_OPTION) {
            // System.exit(0);
        // } else if (choice == JOptionPane.CLOSED_OPTION) {
            // System.exit(0);
        // }
        
        
        
    }

Answer 1

当您按下“退出”或“取消”按钮时，您将“选择”分配给 null，但这不起作用，因为选择是一个 int。您可以“选择”一个字符串，然后在 switch 语句之前，确保选择！= null。这就是它的样子

public static void start() {
        String choice = JOptionPane.showInputDialog(null, "Choice: \n 1 - Play a game \n 2 - show all games \n 3 - Find the best score \n 4 - Find a player \n 5 - End");
       if(choice!=null) {
        switch (choice) {
                case "1":
                    play();
                    break;
                case "2":
                    allGames();
                    break;
                case "3":
                    getBestScore();
                    break;
                case "4":
                    getPlayer();
                    break;
                case "5":
                    System.exit(0);
                    break;
                default:
                    JOptionPane.showMessageDialog(null, "Wrong input.");
                    break;
                    }
        }
}