如下代码,如下所示:
public class app extends javax.swing.JFrame implements Runnable {
扩展 JFrame。但我还需要它来扩展 JPanel,以便制作一个透明的 JPanel。问题是我不能同时扩展两者,java 会抛出一个错误:
如果我扩展 JPanel,我可以制作一个透明的 JPanel,但是程序无法运行,因为有几行代码有错误(如果我扩展 JFrame,错误就会消失)。
但是,如果我扩展 JFrame,该程序将运行得很好,但它使我无法执行透明的 JPanel。我该如何解决这个问题?
最佳答案
基本上,创建从 JPanel
扩展的自定义类,将 setOpaque
设置为 false 以使其透明。
创建一个 JFrame
的实例,将其设置为未修饰并单独调整其不透明度。
将自定义面板添加到框架中...
示例
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TransparentPanel {
public static void main(String[] args) {
new TransparentPanel();
}
public TransparentPanel() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new BorderLayout());
try {
BufferedImage img = ImageIO.read(new File("/Users/swhitehead/Dropbox/MegaTokyo/issue459.jpg"));
final JLabel label = new JLabel(new ImageIcon(img.getScaledInstance(-1, 200, Image.SCALE_SMOOTH)));
label.setLayout(new CardLayout());
JPanel menu = new JPanel(new GridBagLayout());
JButton button = new JButton("Show");
menu.add(button);
JPanel transparent = new JPanel(new GridBagLayout());
transparent.setOpaque(false);
transparent.add(new JLabel("Look, I'm see through"));
label.add(menu, "menu");
label.add(transparent, "transparent");
CardLayout layout = (CardLayout) label.getLayout();
layout.show(label, "menu");
button.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
CardLayout layout = (CardLayout) label.getLayout();
layout.show(label, "transparent");
}
});
add(label);
} catch (IOException exp) {
exp.printStackTrace();
}
}
}
}
关于java - "Extends JFrame"和 JPanel?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18690530/