Question

我正在尝试使用showInputDialog让用户在想要退出程序时输入N或n。我正在使用do-while循环，我认为我的逻辑是错误的。当我输入N或n时，程序继续运行循环。

以下是我的代码：

public static void main(String args[]) {
    MyClass app = new MyClass();
    String quit;
    // get user input until they quit
    do {

        boolean validEntry1 = false;
        do {
            String userEntry;
            double num1;
            // check for valid numerical entry and catch invalid entries
            try {
                userEntry = JOptionPane
                        .showInputDialog("Enter number 1");
                num1 = Double.parseDouble(userEntry);
                app.setNumberOne(num1);
                validEntry1 = true;

            } catch (NumberFormatException e) {
                JOptionPane.showMessageDialog(null,
                        "Please enter a valid number");
            }
        } while (!validEntry1);

        // gets user input for number 2
        boolean validEntry2 = false;
        do {
            String userEntry1;
            double num2;
            // check for valid numerical input for num2
            try {
                userEntry1 = JOptionPane
                        .showInputDialog("Enter number 2");
                num2 = Double.parseDouble(userEntry1);
                app.setNumberTwo(num2);
                validEntry2 = true;
            } catch (NumberFormatException e) {
                JOptionPane.showMessageDialog(null,
                        "Please enter a valid number");
            }
        } while (!validEntry2);

         //this method gives the result of a multiplying num1 and num2
         app.output();

        // prompt user to continue
        quit = JOptionPane
                .showInputDialog("Enter N or n to quit. Enter any other key to continue.");

    } while (quit != "N" || quit != "n"); //this is where I am having issues, It continues to loop regardless of what I enter.
}// end of main

关于我哪里出错的任何建议？

有没有更好的方法让用户输入退出gui？

Answer 1

退出是String，您应该使用.equalsIgnoreCase()进行比较。

试试这样：

while (!quit.equalsIgnoreCase("n"));

字符串是对象，因此它们使用equals方法进行比较，或者在这种情况下，您可以使用equalsIgnoreCase两种情况。

使用showInputDialog获取用户输入以退出程序

1 个答案: