java 新手求问cannot be resolved to a type 的解决方法

Question

这是我自学的一个项目，以前没发现这样的问题，jdk8.65，eclipse是最新版，看了网上的同类问题好像是jar包导入的问题，但是不知道具体怎样解决，请路过的大神指点迷津，万分感谢

import java.awt.*;
import java.awt.event.*;

public class ChatClient extends Frame{

    TextArea ta = new TextArea();
    TextField t = new TextField();

    public static void main(String[] args) {
        new ChatClient().launchFrame();

    }

    public void launchFrame() {
        setLocation(300,300);
        setVisible(true);
        add(ta,BorderLayout.NORTH);
        add(t,BorderLayout.SOUTH);
        pack();
        this.addWindowListener(new myMonitor());

        class myMonitor extends WindowAdapter {
            public void WindowClosing(WindowEvent e) {
                System.exit(0);
            }
        }
    }   
}

Answer 1

 import java.awt.*;
import java.awt.event.*;

public class ChatClient extends Frame{

    TextArea ta = new TextArea();
    TextField t = new TextField();

    public static void main(String[] args) {
        new ChatClient().launchFrame();

    }
   class myMonitor extends WindowAdapter {//类定义不能写在方法里面
            public void WindowClosing(WindowEvent e) {
                System.exit(0);
            }
        }
    public void launchFrame() {
        setLocation(300,300);
        setVisible(true);
        add(ta,BorderLayout.NORTH);
        add(t,BorderLayout.SOUTH);
        pack();
        this.addWindowListener(new myMonitor());


    }   
}