//ExitableJFrame.java
import javax.swing.*;
public class ExitableJFrame extends JFrame{
//构造函数
public ExitableJFrame(){
}
//带窗口标题的构造函数
public ExitableJFrame(String title){
super(title);
}
//窗口的初始化
protected void frameInit(){
super.frameInit();
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
}
//MyCanvas.java
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class MyCanvas
implements KeyListener,MouseListener{
//变量定义
Canvas c;
String s ="";
TextField t;
//主函数
public static void main(String args[]){
Frame f = new Frame("Canvas");
MyCanvas mc = new MyCanvas();
mc.c = new Canvas();
mc.t = new TextField();
f.add("South",mc.t);
f.add("Center",mc.c);
f.setSize(300,150);
mc.c.addMouseListener(mc);
mc.c.addKeyListener(mc);
f.setVisible(true);
}
//响应键盘事件
public void keyTyped(KeyEvent ev){
t.setText("keyTyped");
s+=ev.getKeyChar();
c.getGraphics().drawString(s,0,20);
}
//响应键盘按下
public void keyPressed(KeyEvent ev){ }
//响应键盘抬起
public void keyReleased(KeyEvent ev){
t.setText("keyReleased");
}
//响应点击鼠标
public void mouseClicked(MouseEvent ev){
t.setText("mouseClicked");
c.requestFocus();
}
//响应压下鼠标
public void mousePressed(MouseEvent ev){
t.setText("mousePressed");
}
//响应松开鼠标
public void mouseReleased(MouseEvent ev){
t.setText("mouseReleased");
}
//响应鼠标进入
public void mouseEntered(MouseEvent ev){
t.setText("mouseEntered");
}
//响应鼠标退出
public void mouseExited(MouseEvent ev){
t.setText("mouseExited");
}
}
上面的两个super用法是什么意思？不知道不用那两条语句能运行吗？看得不是很懂，请各位大虾指教下
谢谢！！
