Java初学者请教

Question

见代码如下://===============ButtonEvent.java=================
import java.awt.*;
import java.awt.event.*;import javax.swing.*;
//import MyWindowListener;
public class ButtonEventTest extends JFrame 
implements ActionListener
{
JButton button=new JButton("Click Me");
JTextArea textArea=new JTextArea(2,20);
Container c;
int clickCount=0;
public ButtonEventTest()
{
super("ButtonEvent.java:按钮事件测试");
c=getContentPane();
c.setLayout(new FlowLayout());
c.add(button);
c.add(textArea);
setSize(300,120);
show();
button.addActionListener(this);
}
public void actionPerFormed(ActionEvent e)
{
clickCount++;
textArea.setText("您按Click Me钮"+clickCount+"次");
}
public static void main(String args[])
{
ButtonEventTest app=new ButtonEventTest();
app.addWindowListener(new MyWindowListener());
}
}
//=============MyWindowListener.java=============
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
class MyWindowListener extends WindowAdapter
{
public void windwosClosing(WindowEvent e)
{
System.exit(1);
}
}在Eclipse里运行，会在public class ButtonEventTest extends JFrame 报错。类型 ButtonEventTest 必须实现继承的抽象方法 ActionListener.actionPerformed（ActionEvent）
不太明白，这个是书上的例题。请高手指点。

Answer 1

可以运行，报错信息如下：
Exception in thread "AWT-EventQueue-0" java.lang.AbstractMethodError: ButtonEventTest.actionPerformed(Ljava/awt/event/ActionEvent;)V
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6134)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
at java.awt.Component.processEvent(Component.java:5899)
at java.awt.Container.processEvent(Container.java:2023)
at java.awt.Component.dispatchEventImpl(Component.java:4501)
at java.awt.Container.dispatchEventImpl(Container.java:2081)
at java.awt.Component.dispatchEvent(Component.java:4331)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4301)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3965)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3895)
at java.awt.Container.dispatchEventImpl(Container.java:2067)
at java.awt.Window.dispatchEventImpl(Window.java:2458)
at java.awt.Component.dispatchEvent(Component.java:4331)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Answer 2

不是public void actionPerFormed(ActionEvent e)
是f小写的
actionPerformed