Java Swing revalidate() 与 repaint()

Java Swing中的revalidate()和repaint()方法是用于更新和重绘Swing组件的重要方法。在本文中，我们将深入探讨这两个方法的作用和用法，并分享一些示例代码来帮助读者更好地理解它们。

java
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class RevalidateExample extends JFrame {
    private JLabel label;
    public RevalidateExample() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Revalidate Example");
        setLayout(new FlowLayout());
        label = new JLabel("Click the button to update the label");
        add(label);
        JButton button = new JButton("Update Label");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                label.setText("New Message: " + System.currentTimeMillis());
                revalidate();
            }
        });
        add(button);
        pack();
        setVisible(true);
    }
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new RevalidateExample();
            }
        });
    }
}

java
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
public class RepaintExample extends JFrame {
    private JPanel drawPanel;
    public RepaintExample() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Repaint Example");
        setLayout(new BorderLayout());
        drawPanel = new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(getRandomColor());
                g.fillRect(50, 50, 200, 200);
            }
        };
        add(drawPanel, BorderLayout.CENTER);
        JButton button = new JButton("Draw Rectangle");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                drawPanel.repaint();
            }
        });
        add(button, BorderLayout.SOUTH);
        setSize(300, 300);
        setVisible(true);
    }
    private Color getRandomColor() {
        Random random = new Random();
        int r = random.nextInt(256);
        int g = random.nextInt(256);
        int b = random.nextInt(256);
        return new Color(r, g, b);
    }
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new RepaintExample();
            }
        });
    }
}