import java.awt.Frame;
import java.awt.TextArea;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;public class KeyEventDemo implements KeyListener {public KeyEventDemo(){
}public void keyPressed(KeyEvent arg0) {
System.out.println("<--处理keyReleased事件-->");
TextArea area = (TextArea) arg0.getSource();
String s = area.getText().toUpperCase();
area.setText("");
area.append(s);
}public static void main(String[] args) {
Frame frame = new Frame("容器");
frame.setLocation(200,200);
frame.setSize(300,300);
TextArea area = new TextArea();
area.addKeyListener(new KeyEventDemo());
frame.add(area);
frame.setVisible(true);
}
}有何问题?是否要重写KeyListener方法?编译时出现问题拉!
这样写的话,你必须实现KeyListener的三个方法
void keyTyped(KeyEvent e)
void keyPressed(KeyEvent e)
void keyReleased(KeyEvent e)当然你可以空实现的
public void keyTyped(KeyEvent e){}
public void keyReleased(KeyEvent e){}
就行
KeyEventDemo.java:7: KeyEventDemo is not abstract and does not override abstract
method keyReleased(java.awt.event.KeyEvent) in java.awt.event.KeyListener
public class KeyEventDemo implements KeyListener {
^
1 error