在一添加进JFrame中的jPanel上绘图

Question

想画一个圆。有两个JPanel，jp添加了两个JButton,想在show上画圆。现在不能画出圆来。觉得从那里看过，画的圆被show覆盖，可是repaint()以后还是不行
但是如果利用/**/当中部分，既把画圆做成类，做成底层JPanel，就可以。可是不想这样子
按现在这代码应该怎样修改那import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class Clock1{
  public static void main(String[] args){
    ClockFrame frame=new ClockFrame();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}
class ClockFrame extends JFrame{
  ClockPanel panel=new ClockPanel();
  public ClockFrame(){
    setTitle("clock");  
    setSize(200,200);
    add(panel);
  }
}
class ClockPanel extends JPanel{
  private JPanel jp=new JPanel();
  private JPanel show=new JPanel();
  /* private JPanel show=new JPanel(); */
  private JButton modify=new JButton("modify");
  private JButton ok=new JButton("ok");
  public ClockPanel(){
    setLayout(new BorderLayout());
    setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(),"clock"));
    show.setBackground(Color.RED);
    jp.add(ok);
    jp.add(modify);
    add(show);   
    jp.setLayout(new FlowLayout());
    add(jp,BorderLayout.NORTH);
    repaint();
  }
  public void paintComponent(Graphics g){
    super.paintComponent(g);
    g.drawOval(60,60,100,100);
  }}
/*
class DrawPanel1 extends JPanel{
  public void paintComponent(Graphics g){
    super.paintComponent(g);
    g.drawOval(60,60,100,100);
  }
}*/

Answer 1

你原来画的原是被show这个面板给盖住了，其实将show这个面板去掉就可以了，这里给你贴一个能看到表盘的实例import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class Clock1{
  public static void main(String[] args){
    ClockFrame frame=new ClockFrame();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}
class ClockFrame extends JFrame{
  ClockPanel panel=new ClockPanel();
  public ClockFrame(){
    setTitle("clock");
    setSize(200,200);
    this.getContentPane().add(panel);
//    add(panel);
    this.repaint(); 
  }
}
class ClockPanel extends JPanel{
  private JPanel jp=new JPanel();
//  private JPanel show=new JPanel();
  /* private JPanel show=new JPanel(); */
  private JButton modify=new JButton("modify");
  private JButton ok=new JButton("ok");
  public ClockPanel(){
    setLayout(new BorderLayout());
    setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(),"clock"));
    setBackground(Color.RED);
    jp.add(ok);
    jp.add(modify);
//    add(show);
    jp.setLayout(new FlowLayout());
    add(jp,BorderLayout.NORTH);
//    repaint();
  }
    
  @Override
  public void paintComponent(Graphics g){
    super.paintComponent(g);
    g.drawOval(60,60,100,100);
    System.out.println("-----paintComponent------");
  }}

Answer 2

this.getContentPane().add(panel);
这句要代替add(panel)

Answer 3

最初需要显得到内容窗格contentPane。后来发现脑子转不过来的人太多，Sun就让可以使用add直接添加组件了。import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class Clock{
    public static void main(String[] args){
        java.awt.EventQueue.invokeLater(new Runnable(){
                @Override public void run(){
                    JFrame frame=new JFrame("Clock");
                    frame.setSize(200,200);
                    frame.add(new ClockPanel());
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.setVisible(true);
                }
            });
    }
    static class ClockPanel extends JPanel{
        private JPanel jp=new JPanel();
        private JButton modify=new JButton("modify");
        private JButton ok=new JButton("ok");
        public ClockPanel(){
            super(new BorderLayout());
            setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(),"Clock"));
            setBackground(Color.RED);
            jp.add(ok);
            jp.add(modify);
            jp.setOpaque(false);
            add(jp,BorderLayout.NORTH);
        }
        @Override public void paintComponent(Graphics g){
            super.paintComponent(g);
            g.drawOval(60,60,100,100);
            System.out.println("-----paintComponent------");
        }
    }
}

Answer 4

这样子我知道，我也知道画图被show这个panel给覆盖了。我想知道怎么不被它覆盖，show这个panel也存在。我setBoard不是主要set的show，把按钮都放在了边界外。如果把不加show的画，那setBoard就是整个frame了。而且两个JButton也在这个边界里了

Answer 5

这样子我知道，我也知道画图被show这个panel给覆盖了。我想知道怎么不被它覆盖，show这个panel也存在。我setBoard不是主要set的show，把按钮都放在了边界外。如果把不加show的画，那setBoard就是整个frame了。而且两个JButton也在这个边界里了

Answer 6

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.border.*;import java.util.*;public class Clock{
    public static void main(String[] args){
        java.awt.EventQueue.invokeLater(new Runnable(){
                @Override public void run(){
                    JFrame frame=new JFrame("Clock");
                    frame.setSize(400,400);
                    frame.add(new ClockPanel());
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.setVisible(true);
                }
            });
    }
    static class ClockPanel extends JPanel{
        private JPanel jp=new JPanel();
        private JButton modify=new JButton("modify");
        private JButton ok=new JButton("ok");
        private JPanel drawing = new DrawingPad();
        public ClockPanel(){
            super(new BorderLayout());
            setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(),"Clock"));
            setBackground(Color.RED);
            jp.add(ok);
            jp.add(modify);
            jp.setOpaque(false);
            add(jp,BorderLayout.NORTH);
            // drawing.setOpaque(false);
            add(drawing,BorderLayout.CENTER);
        }
    }
    static class DrawingPad extends JPanel{        @Override public void paintComponent(Graphics g){
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D)g;
            g2d.setPaint(Color.BLACK);
            g2d.draw(new Ellipse2D.Double(60D,60D,100D,100D));
        }
    }
}