写了一个窗口中有一个小球，当碰到边框时球改变颜色。但是现在写的程序只能显现出边框，不能显示出球。求各位看看指出下错误啊
import java.awt.*;
import java.awt.event.*;
import java.awt.Graphics;
class Mywindow extends Frame {
Mywindow (){
super();
setSize(350,350);
setVisible(true);
setBackground(Color.BLACK);
validate();
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
}
}
public class lsnfinal extends Frame implements Runnable{
int x=0,y=160;
int dx=5,dy=0;
int rgb=0;
Color color=new Color((int)(Math.random()*0xFFFFFF));
Mywindow win;
public static void main(String[] args){
lsnfinal workStart=new lsnfinal();
}
public lsnfinal(){
Mywindow win=new Mywindow();
new Thread(this).start();
}
public void doColor(){
rgb=(int)(Math.random()*0xFFFFFF);
color=new Color(rgb);
}
public void run(){
while(true){
if(x<=0) {dx=5;doColor();}
else if((x+50)>=win.getWidth()) {dx=-5; doColor();}
if(y<=0) {dy=5;doColor();}
else if((y+50)>=win.getHeight()) {dy=-5; doColor();}
x=x+dx;
y=y+dy;
repaint();
try{Thread.sleep(250);}
catch(InterruptedException e) {;}
}
}
public void paint(Graphics g){
g.setColor(color);
g.fillOval(x,y,50,50);
}
}
------解决方案--------------------
- Java code
import java.awt.*;import java.awt.event.*;import java.awt.Graphics;public class lsnfinal extends Frame implements Runnable { int x = 60, y = 160; int dx = 5, dy = 0; int rgb = 0; Color color = new Color((int)(Math.random() * 0xFFFFFF)); public static void main(String[] args) { new lsnfinal(); } public lsnfinal(){ setSize(350, 350); setBackground(Color.gray); this.setLayout(null); addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); setVisible(true); new Thread(this).start(); } public void doColor() { rgb = (int)(Math.random()*0xFFFFFF); color = new Color(rgb); } public void run() { while (true) { if (x <= 0) { dx = 5; doColor(); } else if ((x + 50) >= this.getWidth()) { dx = -5; doColor(); } if (y <= 0) { dy = 5; doColor(); }else if ((y + 50) >= this.getHeight()){ dy = -5; doColor(); } x = x + dx; y = y + dy; try { Thread.sleep(50); repaint(); } catch (InterruptedException e) { e.printStackTrace(); } } } public void paint(Graphics g) { Color c = g.getColor(); g.setColor(color); g.fillOval(x, y, 50, 50); g.setColor(c); }}
------解决方案--------------------
或者
- Java code
import java.awt.*;import java.awt.event.*;import java.awt.Graphics;class Mywindow extends Frame { Frame f; Mywindow(Frame frame) { this.f = frame; setSize(350, 350); setBackground(Color.black); this.setLayout(null); addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); setVisible(true); } public void paint(Graphics g){ f.paint(g); }}public class lsnfinal extends Frame implements Runnable { int x = 60, y = 160; int dx = 5, dy = 0; int rgb = 0; Color color = new Color((int)(Math.random() * 0xFFFFFF)); Mywindow win = null; public static void main(String[] args) { new lsnfinal(); } public lsnfinal(){ win = new Mywindow(this); new Thread(this).start(); } public void doColor() { rgb = (int)(Math.random()*0xFFFFFF); color = new Color(rgb); } public void run() { while (true) { if (x <= 0) { dx = 5; doColor(); } else if ((x + 50) >= win.getWidth()) { dx = -5; doColor(); } if (y <= 0) { dy = 5; doColor(); }else if ((y + 50) >= win.getHeight()){ dy = -5; doColor(); } x = x + dx; y = y + dy; try { Thread.sleep(250); win.repaint(); } catch (InterruptedException e) { e.printStackTrace(); } } } public void paint(Graphics g) { Color c = g.getColor(); g.setColor(color); g.fillOval(x, y, 50, 50); g.setColor(c); }}