Question

一个Frame中有多个Panel，想在其中一个指定的Panel中画图，怎么实现呢

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Answer 1

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.BevelBorder;

public class Test extends JFrame
{
    private static final long serialVersionUID = 1L;

    Test()
    {
        setSize(400, 300);
        setLayout(new FlowLayout());
        int num = 10;
        int rand = (int) (Math.random() * num);
        for(int i = 0; i < num; i++)
        {
            JPanel panel;
            if(i == rand)
            {
                panel = new JPanel()
                {
                    private static final long serialVersionUID = 1L;

                    @Override
                    public void paint(Graphics g)
                    {
                        super.paint(g);
                        g.setColor(Color.orange);
                        g.fillOval(15, 15, 20, 20);
                        g.dispose();
                    }
                };
            }
            else
            {
                panel = new JPanel();
            }
            panel.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED, Color.red, Color.black));
            panel.setPreferredSize(new Dimension(40, 50));
            add(panel);
        }
        setLocationRelativeTo(null);
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public static void main(String[] args)
    {
        new Test().setVisible(true);
    }
}

追问

只用awt能实现吗

追答

// 道理是一样的，采纳即可

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Panel;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class Test extends Frame
{
private static final long serialVersionUID = 1L;

Test()
{
setSize(400, 300);
setLayout(new FlowLayout());
int num = 10;
int rand = (int) (Math.random() * num);
for(int i = 0; i < num; i++)
{
Panel panel;
if(i == rand)
{
panel = new Panel()
{
private static final long serialVersionUID = 1L;

@Override
public void paint(Graphics g)
{
super.paint(g);
g.setColor(Color.orange);
g.fillOval(15, 15, 20, 20);
g.dispose();
}
};
}
else
{
panel = new Panel();
}
panel.setBackground(Color.gray);
panel.setPreferredSize(new Dimension(40, 50));
add(panel);
}
setLocationRelativeTo(null);
setResizable(false);
addWindowListener(new WindowAdapter()
{
@Override
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
}
public static void main(String[] args)
{
new Test().setVisible(true);
}
}

追问

还是无法显示，头疼……