import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class Test extends Canvas implements KeyListener {
int index;
Color colors[]={Color.red,Color.green,Color.blue};
public void paint(Graphics g) {
g.setColor(colors[index]);
g.fillRect(0,0,getSize().width,getSize().height);
}
public static void main(String args[]) {
Frame f=new Frame("Canvas");
Test mc=new Test();
f.add(mc,BorderLayout.CENTER);
f.setSize(150,150);
mc.requestFocus();
mc.addKeyListener(mc);
f.setVisible(true);
}
public void keyTyped(KeyEvent ev) {
index++;
if(index==colors.length) {
index=0;
}
repaint();
}
public void keyPressed(KeyEvent ev) {
}
public void keyReleased(KeyEvent ev) {
}
}
import java.awt.event.*;
import java.util.*;
public class Test extends Canvas implements KeyListener {
int index;
Color colors[]={Color.red,Color.green,Color.blue};
public void paint(Graphics g) {
g.setColor(colors[index]);
g.fillRect(0,0,getSize().width,getSize().height);
}
public static void main(String args[]) {
Frame f=new Frame("Canvas");
Test mc=new Test();
f.add(mc,BorderLayout.CENTER);
f.setSize(150,150);
mc.requestFocus();
mc.addKeyListener(mc);
f.setVisible(true);
}
public void keyTyped(KeyEvent ev) {
index++;
if(index==colors.length) {
index=0;
}
repaint();
}
public void keyPressed(KeyEvent ev) {
}
public void keyReleased(KeyEvent ev) {
}
}
at sun.applet.AppletPanel.createApplet(AppletPanel.java:721)
at sun.applet.AppletPanel.runLoader(AppletPanel.java:650)
at sun.applet.AppletPanel.run(AppletPanel.java:324)
at java.lang.Thread.run(Thread.java:595)大家帮帮忙,这是什么原因啊?
public class ClassCastExceptionextends RuntimeException当试图将对象强制转换为不是实例的子类时,抛出该异常。例如,以下代码将生成一个 ClassCastException:
Object x = new Integer(0);
System.out.println((String)x);
你好好看看吧我也是新手