java制作目录查询器 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();
}
}