老师，没有弄懂，就参考同学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<itme.length;i++){ box.addItem(itme[i]); } box.setEnabled(true); box.setEditable(true); box.setMaximumRowCount(6); box.setBounds(230,30,130,25); frame.setBounds(400,300,400,200); frame.setVisible(true); JTextArea main_text =new JTextArea(); main_text.setBackground(Color.BLACK); JScrollPane AA=new JScrollPane(); AA.setViewportView(main_text); main_text.setEnabled(false); main_panel.add(box,BorderLayout.NORTH); main_panel.add(AA,BorderLayout.CENTER); frame.add(main_panel); try { String str=FileUtils.listDirectory(new File("C:\\Users\\Administrator\\Desktop\\Java作业5\\soundPlayer\\audio")); main_text.setText(str); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } frame.setBounds(300,400,300,400); frame.setVisible(true); }} 