Question

在我的程序中，我使用JOptionPane.showConfirmDialog来提示用户是否确定要退出模拟;如果你点击＆＃34;否＆＃34; prgoram应打印出来＆＃34;继续siumlation ...＆＃34;并继续使用该程序，但我发现当你点击否它打印出来＆＃34;继续模拟＆＃34;然后直接在＆＃34;维护将不会执行，退出模拟......＆＃34; 无论如何可以帮助我找出为什么会发生这种情况？

            if(main.equalsIgnoreCase("N") | main.equalsIgnoreCase("NO")){
                result = JOptionPane.showConfirmDialog(null, "WARNING! Are you sure you don't want to carry out maintenance? The simulation will stop if you click YES.  ", "TERMINATE THE SIMULATION? ", JOptionPane.YES_NO_OPTION);
                if(JOptionPane.NO_OPTION == result){
                    System.out.println("Continuing Simulation...");
                }
                if (JOptionPane.YES_OPTION == result) {
                    Result2 = JOptionPane.showConfirmDialog(null, "Are you sure you want to exit the simulation?", "Are You Sure?", JOptionPane.YES_NO_OPTION);
                } 
                if(JOptionPane.YES_OPTION == Result2){
                    System.out.println("Maintenance will not be carried out, exiting Simulation...");
                    try{
                        System.exit(0);
                    }
                    finally{
                        System.err.println("Exiting...");
                        System.exit(1);
                    }
                }
                if (JOptionPane.NO_OPTION == Result2) {
                    System.out.println("Continuing simulation...");
            }
            }

Answer 1

如果您点击＆＃34;否＆＃34;在第一个对话框中，您没有为Result2分配任何值，因为您没有显示第二个对话框。但是，您仍然在此if语句Result2中使用if(JOptionPane.YES_OPTION == Result2){的值。

问题是，如果Result2是一个实例变量，而您尚未为其分配值，则它具有类型int的默认值，即零

常数JOptionPane.YES_OPTION的值也为零。因此，if语句的计算结果为true，并打印出维护消息并退出。

您应该嵌套if语句，以便只有在为其分配了有意义的值时才会检查Result2的值，如下所示：

if (JOptionPane.YES_OPTION == result) {
    Result2 = JOptionPane.showConfirmDialog(null, "Are you sure you want to exit the simulation?", "Are You Sure?", JOptionPane.YES_NO_OPTION);
    if(JOptionPane.YES_OPTION == Result2){
        System.out.println("Maintenance will not be carried out, exiting Simulation...");
        try{
            System.exit(0);
        }
        finally{
            System.err.println("Exiting...");
            System.exit(1);
        }
    }
    if (JOptionPane.NO_OPTION == Result2) {
        System.out.println("Continuing simulation...");
    }
}

Answer 2

试试这个：

if(main.equalsIgnoreCase("N") | main.equalsIgnoreCase("NO")){
            result = JOptionPane.showConfirmDialog(null, "WARNING! Are you sure you don't want to carry out maintenance? The simulation will stop if you click YES.  ", "TERMINATE THE SIMULATION? ", JOptionPane.YES_NO_OPTION);
            if(JOptionPane.NO_OPTION == result){
                System.out.println("Continuing Simulation...");
            }else{
            if (JOptionPane.YES_OPTION == result) {
                Result2 = JOptionPane.showConfirmDialog(null, "Are you sure you want to exit the simulation?", "Are You Sure?", JOptionPane.YES_NO_OPTION);
            }
            if(JOptionPane.YES_OPTION == Result2){
                System.out.println("Maintenance will not be carried out, exiting Simulation...");
                try{
                    System.exit(0);
                }
                finally{
                    System.err.println("Exiting...");
                    System.exit(1);
                }
            }
            if (JOptionPane.NO_OPTION == Result2) {
                System.out.println("Continuing simulation...");
            }
        }}

您需要在if(JOptionPane.NO_OPTION == result)

之后加上其他内容

Answer 3

if（main.equalsIgnoreCase（“N”）| main.equalsIgnoreCase（“NO”））使用按位包含OR运算符“|”。尝试使用逻辑OR运算符“||”代替：

if(main.equalsIgnoreCase("N") || main.equalsIgnoreCase("NO")){

单击按钮后，为什么我的程序输出错误？

3 个答案: