问题描述
自定义组件为0x0 px。
import java.awt.*;
import javax.swing.*;
public class Catch {
public class MyGraphics extends JComponent {
private static final long serialVersionUID = 1L;
MyGraphics() {
setPreferredSize(new Dimension(500, 100));
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.fillRect(200, 62, 30, 10);
}
}
public void createGUI() {
final JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.add(new MyGraphics());
frame.add(panel);
frame.pack();
frame.setVisible(true);
frame.setDefaultCloSEOperation(JFrame.DISPOSE_ON_CLOSE);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
Catch GUI = new Catch();
GUI.createGUI();
}
});
}
}
解决方法
我在向JPanel添加图形时遇到问题。如果我更改从panel.add（new graphics（））; 到frame.add（new
graphics（））;
并且不要将JPanel添加到JFrame，黑色矩形会出现在JFrame上。我只是无法让黑色矩形出现在JPannel上，并且想知道是否有人可以帮助我。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Catch{
public class graphics extends JComponent{
public void paintComponent(Graphics g){
super.paintComponents(g);
g.fillRect(200,62,30,10);
}
}
public void createGUI(){
final JFrame frame = new JFrame();
JPanel panel = new JPanel();
frame.setSize(500,500);
frame.addMouseListener(new MouseAdapter(){
public void mouseClicked(MouseEvent e) {
System.out.println(e.getPoint().getX());
System.out.println(e.getPoint().getY());
}
});
panel.add(new graphics());
frame.add(panel);
frame.setVisible(true);
frame.setDefaultCloseOperation(frame.DISPOSE_ON_CLOSE);
}
public static void main(String[] args){
Catch GUI= new Catch();
GUI.createGUI();
}
}