paint和repaint函数的区别，一定给分

请教paint()与repaint()方法的区别，是否可以自己写一个方法代替paint()或repaint()？我在panel上画了一个图，但移动panel后，图就不见了，why？how to resolve?

11 个解决方案

#1

repaint()方法会执行：update()方法，先刷新屏幕（以背景填充），在调用
paint()方法重画。
一般可以重载update()和paint()方法。

#2

repaint()调用paint(),在APPLET中,可根据自己意图改写paint().

#3

To get rid of the flicker, override update() as follows:
public void update(Graphics g) {
paint(g);
}

#4

问题可能在代码，能看看吗？

#5

to lmy2000:
repaint()方法应该写在哪里才能在我移动Panel时调用repaint()？

#6

另外：我的repaint()方法是在事件处理时才触发的，如何还要保证在屏幕刷新时也触发repaint()方法呢？

#7

paint画的图会被子控件覆盖！

#8

to wangtaoyy:
    void myActionListener_actionPerformed(ActionEvent e)
    {
     repaint(g, x, y, width, height, startAngle, arcAngle, Color.orange);
    ｝

    repaint()方法中重载update（），update（）中重载paint()

#9

使用轻量组件
或重载getInsets()返回合适的值。

#10

Applet子类完全正常
JApplet的子类要在paint方法中先调用父类的paint
以下Applet运行正常
         import java.awt.*;
import java.applet.*;

public class Applet1 extends Applet
{
public void init()
{

setLayout(null);
setSize(426,266);
button1.setLabel("draw");
add(button1);
button1.setBackground(java.awt.Color.lightGray);
button1.setBounds(252,48,112,47);

SymAction lSymAction = new SymAction();
button1.addActionListener(lSymAction);

}

java.awt.Button button1 = new java.awt.Button();

class SymAction implements java.awt.event.ActionListener
{
public void actionPerformed(java.awt.event.ActionEvent event)
{
Object object = event.getSource();
if (object == button1)
button1_ActionPerformed(event);
}
}

void button1_ActionPerformed(java.awt.event.ActionEvent event)
{
repaint();

}
public void paint(Graphics g){
    g.drawRect(20, 20, 100, 100);
}
}
//

以下JApplet运行正常
import java.awt.*;
import javax.swing.*;

/**
* A basic extension of the javax.swing.JApplet class
*/
public class JApplet1 extends JApplet
{
public void init()
{

getContentPane().setLayout(null);
setSize(426,266);
JButton1.setText("draw");
getContentPane().add(JButton1);
JButton1.setBounds(300,108,71,46);
//}}

//{{REGISTER_LISTENERS
SymAction lSymAction = new SymAction();
JButton1.addActionListener(lSymAction);
//}}
}

//{{DECLARE_CONTROLS
javax.swing.JButton JButton1 = new javax.swing.JButton();
//}}

class SymAction implements java.awt.event.ActionListener
{
public void actionPerformed(java.awt.event.ActionEvent event)
{
Object object = event.getSource();
if (object == JButton1)
JButton1_actionPerformed(event);
}
}

void JButton1_actionPerformed(java.awt.event.ActionEvent event)
{
repaint();

}
public void paint(Graphics g){
    super.paint(g);
    g.drawRect(20, 20, 100, 100);
}
}

#11

thanks, i see

#1