import java.awt.Color;import java.awt.BorderLayout;import java.io.File;import java.awt.Container;import java.awt.event.ActionEvent;import java.util.ArrayList;import java.util.List;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JList;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.JTextArea;public class FileUtils extends JFrame{    /**     * 列出指定文件夹（目录）中的所有文件或目录的名额     * @param dri File类型指定的文件夹（目录）     * @throws IllegalAccessException      */      public static String listDirectory(File dir) throws IllegalAccessException{          if(!dir.exists()){        throw new IllegalAccessException("目录"+dir+"不存在");          }                    //判断dir下关联的文件和目录是否存在          if(!dir.isDirectory()){              //如果不存在抛出异常              throw new IllegalAccessException(dir + "不是目录");          }          String[] fileName = dir.list();          String name ="";          for(String a : fileName){              name=name+a+"\n";}           return name;          }             /**     * @param args     */    public static void main(String[] args) {        // TODO Auto-generated method stub         // TODO Auto-generated method stub        JFrame frame=new JFrame();        JPanel main_panel =new JPanel(new BorderLayout());        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        //frame.setLayout(null);        String[] itme =new String[]{
   ".jpg",".zip",".doc"};        JComboBox box=new JComboBox();        for(int i=0;i