Java ActionListener的问题

我得到了这个错误请帮助：我得到了私有类thehandler的错误，它是“第二种类型thehandler必须实现抽象” 方法ActionListener.actionPerformed（ActionEvent）

注意：导入是导入的。我想要一个解决方案，但不是抽象的，因为它会因为某些原因使整个程序崩溃

public class Second extends JFrame {

    private JTextField item1;
    private JTextField item2;
    private JTextField item3;
    private JPasswordField itemp;
    public Second(){
        super("Game");
        setLayout(new FlowLayout());
        item1 = new JTextField(10);
        add(item1);
        item2 = new JTextField("Enter Text Here");
        add(item2);
        item3 = new JTextField("uneditable",20);
        item3.setEditable(false);
        add(item3);
        itemp = new JPasswordField("PASSWORD");
        add(itemp); 
        thehandler handler = new thehandler();
        item1.addActionListener(handler);
        item2.addActionListener(handler);
        item3.addActionListener(handler);
        itemp.addActionListener(handler);

    }
    private class thehandler implements ActionListener{
        public void ActionPerformed(ActionEvent event){
            String string = "";

            if(event.getSource()==item1)
                string = String.format("It's: %s", event.getActionCommand());
            else if(event.getSource()==item2)
                string = String.format("It's: %s", event.getActionCommand());
            else if(event.getSource()==item3)
                string = String.format("It's: %s", event.getActionCommand());
            else if(event.getSource()==itemp)
                string = String.format("It's: %s", event.getActionCommand());

            JOptionPane.showMessageDialog(null, string);






        }


    }

}

Java区分大小写

@Override
public void actionPerformed(ActionEvent event) {

---

谢谢，我没有注意到这一点：）