3个按钮 分别显示画3个圆 可点按钮 没反映 有源程序很小的，程序编译通过， 帮我看看 成心谢谢

Question

定义一个Button 在actionPerformed中获取ee.getSource
在paint(Graphics g) 中判断再设置颜色并画。

Answer 1

import java.awt.*;
import java.applet.*;
import java.awt.event.*;public class Drawing_Ovel extends Applet implements ActionListener
{
Button br=new Button("红"),bg=new Button("绿"),bb=new Button("蓝");
Canvas c=new Canvas();
public void init() 
{
this.setLayout(null);
this.setSize(400,400);
this.setBackground(Color.black);
br.setSize(35,20);br.setLocation(10,10);
bg.setSize(35,20);bg.setLocation(50,10);
bb.setSize(35,20);bb.setLocation(100,10);
c.setSize(300,300);
c.setBackground(Color.yellow);
add(br);add(bg);add(bb);
add(c);
br.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
c.setBackground(Color.red);
repaint();
}
});
bg.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
c.setBackground(Color.green);
repaint();
}
});
bb.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
c.setBackground(Color.blue);
repaint();
}
});
}
public void actionPerformed(ActionEvent ee)
{
repaint();
}
}

Answer 2

if((Button)ee.getSource()==br)gg.setColor(Color.red);
else
if((Button)ee.getSource()==bg)gg.setColor(Color.green);
else
if((Button)ee.getSource()==bb)gg.setColor(Color.blue);
repaint();

Answer 3

gg.fillOval(50,50,50,50);
换成一个fill(圆的引用好了)

Answer 4

import java.awt.*;
import java.applet.*;
import java.awt.event.*;public class Drawing_Ovel extends Applet implements ActionListener
{
Button br=new Button("红"),bg=new Button("绿"),bb=new Button("蓝");
Canvas c=new Canvas();
         int GraphicsModel;///////////////////////////////////////////////////////////
public void init() 
{
this.setLayout(null);
this.setSize(400,400);
this.setBackground(Color.black);
br.setSize(35,20);br.setLocation(10,10);
bg.setSize(35,20);bg.setLocation(50,10);
bb.setSize(35,20);bb.setLocation(100,10);
c.setSize(300,300);
c.setBackground(Color.yellow);
add(br);add(bg);add(bb);
add(c);
br.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
                                              GraphicsModel=0;
}
});
bg.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
                                              GraphicsModel=1;
}
});
bb.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
                                              GraphicsModel=2;
}
});
}
public void paint(Graphics g)
{
if(GraphicsModel==0)
                   {         g.fill()};/////////////////////////////////////////////
if(GraphicsModel==1)
                   {         g.fill()};////////////////////////////////////////////
if(GraphicsModel==2)
                   {         g.fill()};///////////////////////////////////////////////
}

Answer 5

import java.awt.*;
import java.applet.*;
import java.awt.event.*;public class Drawing_Ovel extends Applet implements ActionListener
{
Button br=new Button("红"),bg=new Button("绿"),bb=new Button("蓝");
Canvas c=new MyCanvas();
Graphics g=c.getGraphics();
public void init() 
{
this.setLayout(null);
this.setSize(400,400);
this.setBackground(Color.black);
br.setSize(35,20);br.setLocation(10,10);
bg.setSize(35,20);bg.setLocation(50,10);
bb.setSize(35,20);bb.setLocation(100,10);
c.setSize(300,300);
c.setBackground(Color.yellow);
add(br);add(bg);add(bb);
add(c);
br.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
Graphics g=c.getGraphics();
g.setColor(Color.red);
g.fillOval(50,50,50,50);
repaint();
}
});
bg.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
Graphics g=c.getGraphics();
g.setColor(Color.green);
g.fillOval(50,50,50,50);
repaint();
}
});
bb.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ee)
{
Graphics g=c.getGraphics();
g.setColor(Color.blue);
g.fillOval(50,50,50,50);
repaint();
}
});
}
public void actionPerformed(ActionEvent ee)
{
repaint();
}
}
class MyCanvas extends Canvas
{ public void paint(Graphics gg)
{
gg.setColor(Color.red);
gg.fillOval(50,50,50,50);
}
}

Answer 6

不可能啊!
<HTML>
<applet code="Drawing_Ovel.class" width=400 height=200>
</applet>
</HTML>不要用IE,可能plug-in有问题.用appletviewer ?.html

Answer 7

我是用JCreator 建立的工程 运行的啊 
你也运行一下看看可以不？

Answer 8

帮你改了改，看这个行不
import java.awt.*;
import java.applet.*;
import java.awt.event.*;public class Cir extends Applet implements ActionListener
{
Button br=new Button("红");
Button bg=new Button("绿");
Button bb=new Button("蓝");
int color=0; public void init() 
{
this.setLayout(null);
this.setSize(400,400);
this.setBackground(Color.black);
br.setSize(35,20);br.setLocation(10,10);
bg.setSize(35,20);bg.setLocation(50,10);
bb.setSize(35,20);bb.setLocation(100,10);
add(br);add(bg);add(bb);
br.addActionListener(this);
bg.addActionListener(this);
bb.addActionListener(this);
} public void actionPerformed(ActionEvent ee)
{
if(ee.getSource()==br)color=1;
else
if(ee.getSource()==bg)color=2;
else
if(ee.getSource()==bb)color=3;
repaint(); } public void paint(Graphics g) 
{
switch (color)
{
case 1: g.setColor(Color.red);break;
case 2: g.setColor(Color.green);break;
case 3: g.setColor(Color.blue);break;
default: g.setColor(Color.black);
}
g.fillOval(50,50,50,50);
}

}

Answer 9

两个问题：
1、要获取canvas的graphics
2、applet没有paint()方法,只有paint(Graphics g)
两者不一样，建议区分使用，否则会画错地方的。
楼主的程序相当于是自定义一个paint方法，所以要显示调用才行。import java.awt.*;
import java.applet.*;
import java.awt.event.*;public class Drawing_Ovel extends Applet implements ActionListener
{
Graphics gg;
Button br=new Button("&ordm;ì"),bg=new Button("&Acirc;&Igrave;"),bb=new Button("&Agrave;&para;");
Canvas c=new Canvas();
public void init() 
{
this.setLayout(null);
this.setSize(400,400);
this.setBackground(Color.black);
br.setSize(35,20);br.setLocation(10,10);
bg.setSize(35,20);bg.setLocation(50,10);
bb.setSize(35,20);bb.setLocation(100,10);
c.setSize(300,300);
c.setBackground(Color.yellow);
add(br);add(bg);add(bb);
add(c);
br.addActionListener(this);
bg.addActionListener(this);
bb.addActionListener(this);
}
public void actionPerformed(ActionEvent ee)
{
gg=c.getGraphics();
if(ee.getSource()==br)gg.setColor(Color.red);
else
if(ee.getSource()==bg)gg.setColor(Color.green);
else
if(ee.getSource()==bb)gg.setColor(Color.blue);
paint();}public void paint() 
{
gg.fillOval(50,50,50,50);
}
}

Answer 10

恩 楼上的2位改的可以用 谢谢
可我还有个程序有问题就
可以在帮我看看吗 
这个程序可以运行 但按按钮没反映 也没有debug显示 可以看看那里有问题吗？
import java.awt.*;
import java.applet.*;
import java.awt.event.*;public class Drawing_Ovel extends Applet implements ActionListener
{
Button br=new Button("红"),bg=new Button("绿"),bb=new Button("蓝");
Canvas c=new Canvas();
         int y=0;
public void init() 
{
this.setLayout(null);
this.setSize(400,400);
this.setBackground(Color.black);
br.setSize(35,20);br.setLocation(10,10);
bg.setSize(35,20);bg.setLocation(50,10);
bb.setSize(35,20);bb.setLocation(100,10);
c.setSize(300,300);
c.setBackground(Color.white);
add(br);add(bg);add(bb);
add(c);
br.addActionListener(this);
bg.addActionListener(this);
bb.addActionListener(this);

}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==br)y=0;
if(e.getSource()==bg)y=1;
if(e.getSource()==bb)y=2;
}

public void paint(Graphics g)
{
if(y==0)
                   {   g.setColor(Color.red);
                         g.fillOval(50,50,50,50);}
if(y==1)
                   {  g.setColor(Color.green);    
                    g.fillOval(50,50,50,50);}
if(y==2)
                   {g.setColor(Color.blue);         
                    g.fillOval(50,50,50,50);}
}
}

Answer 11

还是2个问题：
1、现在用的是applet的grahpics，所以是在applet上画图，而canvas是加在applet上的，所以会覆盖applet所画的图像，所以不要加canvas（即将add(c)去掉）2、每次改变需要用repaint刷新一下
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==br)y=0;
if(e.getSource()==bg)y=1;
if(e.getSource()==bb)y=2;                  repaint();  ////////////////////
}