java - 显示一个窗口以获取用户输入

Question

我是 Java 编程新手。

我有这两个小项目。

import javax.swing.*;

public class tutorial {

    public static void main(String[] args){
        JFrame frame = new JFrame("Test");
        frame.setVisible(true);
        frame.setSize(300,300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JLabel label = new JLabel("hello");
        JPanel panel = new JPanel();
        frame.add(panel);
        panel.add(label);

        JButton button = new JButton("Hello again");
        panel.add(button);
    }
}

还有这个:

import java.util.*;

public class Test {

    public static void main(String[] args){
        int age;
        Scanner keyboard = new Scanner(System.in);
        System.out.println("How old are you?");
        age = keyboard.nextInt();
        if (age<18) 
        {
            System.out.println("Hi youngster!");
        }
        else 
        {
            System.out.println("Hello mature!");
        }
    }

}

如何将第二个代码添加到第一个代码中，以便用户将看到一个窗口，显示“您多大了”，并且他们可以输入自己的年龄。

提前致谢!

Answer 1

我不确定你想要的所有东西，因为它是未定义的，但据我所知，你想要一个包含输入字段的 JFrame，你可以在其中输入值并显示适当的答案。 我还建议您阅读教程，但如果您有疑问，请不要犹豫。 我希望它与您想要的有点接近。

package example.tutorial;

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Tutorial extends JPanel {
    private static final String YOUNG_RESPONSE = "Hi youngster!";
    private static final String ADULT_RESPONSE = "Hello mature!";
    private static final String INVALID_AGE = "Invalid age!";

    private static final int MIN_AGE = 0;
    private static final int MAX_AGE = 100;

    private static JTextField ageField;
    private static JLabel res;

    private Tutorial() {
        setLayout(new BorderLayout());

        JPanel northPanel = new JPanel();
        northPanel.setLayout(new FlowLayout());
        JLabel label = new JLabel("How old are you ? ");
        northPanel.add(label);

        ageField = new JTextField(15);
        northPanel.add(ageField);
        add(northPanel, BorderLayout.NORTH);


        JPanel centerPanel = new JPanel();  
        JButton btn = new JButton("Hello again");
        btn.addActionListener(new BtnListener());
        centerPanel.add(btn);

        res = new JLabel();
        res.setVisible(false);
        centerPanel.add(res);

        add(centerPanel, BorderLayout.CENTER);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Test");
        frame.add(new Tutorial());
        frame.setVisible(true);
        frame.setSize(300, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    private static class BtnListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            String content = ageField.getText();
            int age = -1;
            try{
                age = Integer.parseInt(content);
                if(isValid(age)) {
                    res.setText(age < 18 ? YOUNG_RESPONSE : ADULT_RESPONSE);
                } else {
                    res.setText(INVALID_AGE);
                }
                if(!res.isVisible())
                    res.setVisible(true);
            } catch(NumberFormatException ex) {
                res.setText("Wrong input");
            }
        }

        private boolean isValid(int age) {
            return age > MIN_AGE && age < MAX_AGE;
        }
    }
}