java用外部类监听器来监听按钮

import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;

import javax.swing.JFrame;

public class A extends JFrame {
MenuBar mb = new MenuBar();
Menu m1 = new Menu("系统管理");
MenuItem m11 = new MenuItem("修改密码");
MenuItem m12 = new MenuItem("退出");

public A() {
    this.setSize(300, 200);
    this.setLocationRelativeTo(null);
    this.setVisible(true);
    this.setDefaultCloseOperation(3);
    this.setMenuBar(mb);
    mb.add(m1);
    m1.add(m11);
    m1.add(m12);
    m12.addActionListener(new B());
}

public static void main(String[] args) {
    new A();
}

}

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class B implements ActionListener {

public void actionPerformed(ActionEvent e) {
    A a = new A();
    if(e.getSource() == a.m12) {
        System.exit(0);
    }
}

}

要怎么才能实现？

在B类中加个变量吧，构造函数传参赋值初始化

http://blog.csdn.net/pdw_jsp/article/details/6611431