Question

我想要求用户在showInputDialog中输入整数，但如果输入是非整数值，则catch将起作用。

有人能引导我走向正确的方向吗？

public static void tryCatch(){
    try{
        Scanner scanner = new Scanner(System.in);
        JOptionPane.showMessageDialog(null, "Welcome");
        JOptionPane.showInputDialog(null, "Enter your number");

        int pass = Integer.parseInt(null);

    } catch(InputMismatchException e){
        JOptionPane.showMessageDialog(null, "Invalid number!");
    }   
}

Answer 1

如果你读过JavaDocs for JOptionPane.showInputDialog，你就会看到......

返回：
用户的输入，或null表示用户取消了输入

这意味着您可以将从方法调用返回的结果分配给变量，例如......

String text = JOptionPane.showInputDialog(null, "Enter your number");

有关详细信息，请参阅How to Make Dialogs和JavaDocs for JOptionpane

Answer 2

以下是示例

import javax.swing.*;

/**
 * JOptionPane showInputDialog example #1.
 * A simple showInputDialog example.
 * 
 */
public class JOptionPaneShowInputDialogExample1
{
  public static void main(String[] args)
  {
   // a jframe here isn't strictly necessary, but it makes the example a little more real
   JFrame frame = new JFrame("InputDialog Example #1");

   // prompt the user to enter their num
   int num;

  do {

        try
                {
                    num= Integer.parseInt(JOptionPane.showInputDialog(frame, "Enter the     number"));
                    break;
                }

                catch (NumberFormatException e)
                {
                    JOptionPane.showMessageDialog(null,
                            "Error. Please enter a valid number", "Error",
                            JOptionPane.INFORMATION_MESSAGE);
                }

    } while (true)
   // get the user's input. note that if they press Cancel, 'name' will be null
   System.out.printf("The user's name is '%d'.\n", num);
   System.exit(0);

} }

如何将showInputDialog的输入放在变量中？

2 个答案: