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？我这样试过，但对我不起作用。

它向我显示一个错误，说 choice 是 null 但它不可能是因为它是 int？还有其他解决办法吗？

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，您正在将“选择”分配给 null，但这不起作用，因为选择是一个整数。您可以将“选择”设为一个字符串，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;
                    }
        }
}

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

event when press exit button: JOptionPane.showInputDialog

java

swing