java - 第二个 JOptionPane 不会出现

Question

我刚刚开始接触 Java 和一般编程。有人可以向我解释一下为什么在我输入第一个对话框的信息后第二个对话框不会出现吗？

谢谢!

// Java Practice

import javax.swing.JOptionPane;
import java.util.Scanner;

public class DialogTest 
{
    public static void main(String [] args)
    {
        Scanner keyboard = new Scanner(System.in);

        String firstname;
        String lastname;
        int age;

        JOptionPane.showInputDialog("What is " +
                                    "your first name?");
        firstname = keyboard.nextLine();

        JOptionPane.showInputDialog("What is " +
                                    "your last name?");
        lastname = keyboard.nextLine();

        JOptionPane.showInputDialog("How old are you?");
        age = keyboard.nextInt();

        JOptionPane.showMessageDialog(null, "I see, so your name is: " + firstname + lastname + " and you are" + age + " years old.");

        System.exit(0);
    }
}

Answer 1

JOptionPane.showInputDialog() 返回一个包含用户输入的值的String。不要使用 Scanner 类，而是将方法调用的返回值存储到变量中:

String firstname, lastname, age;

firstname = JOptionPane.showInputDialog("What is " +
                                "your first name?");

lastname = JOptionPane.showInputDialog("What is " +
                                "your last name?");

age = JOptionPane.showInputDialog("How old are you?");

JOptionPane.showMessageDialog(null, "I see, so your name is: " + firstname + lastname + " and you are" + age + " years old.");