JAVA读取文件夹里的文件目录到TXT

package javapackge;
import java.awt.*;
import java.awt.event.*;
import java.io.File;
import javax.swing.JFrame;

class MyWindowDemo{
    private Frame f;
    private TextField tf;
    private Button btn;
    private TextArea ta;
    MyWindowDemo()
    {
        init();
    }
    public void init(){
        f=new JFrame("my window");
        f.setBounds(300, 100, 600, 500);
        f.setLayout(new FlowLayout());
        tf=new TextField(30);
        btn=new Button("转到");
        ta=new TextArea(15,40);
        f.add(tf);
        f.add(btn);
        f.add(ta);
        myEvent();
        f.setVisible(true);    
    }
    private void myEvent(){
        btn.addActionListener(new ActionListener() {            
            public void actionPerformed(ActionEvent e) {
                String dirpath=tf.getText();
                File dir=new File(dirpath);
                if(dir.exists() && dir.isDirectory()){
                    ta.setText("");
                    String[]names=dir.list();
                    for(String name : names){
                        ta.append(name+"\r\n");
                    }
                }
            }
        });
        
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e){
                System.exit(0);
            }
        });
    }
}
public class Dumulu {

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

    }

}