利用java制作一个小的目录查询器的方法

import java.util.*;import javax.swing.*;import java.awt.*;import java.io.*;import java.awt.event.*;class MyWindow{private Frame f1;private Button bt1;private TextField tx1;private TextArea tx2;MyWindow(){init();}public void init(){f1=new Frame("窗体");f1.setBounds(300,100,600,500);f1.setLayout(new FlowLayout());bt1=new Button("按钮");tx1=new TextField(30);tx2=new TextArea(25,70);f1.add(tx1);f1.add(bt1);f1.add(tx2); event();f1.setVisible(true);} private void event(){bt1.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){String dirpath=tx1.getText();File dir =new File(dirpath);if(dir.exists()&& dir.isDirectory()){String names[] =dir.list();for(String name:names){tx2.setText(name+"/r/n");}}// System.out.println(s);//tx2.append(s);}});f1.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent E){System.exit(0);}});}public static void main(String args[]){new MyWindow();}}