import java.awt.*;import java.awt.event.*;import java.io.*;/** 這段程序模擬windows用記事本打開.txt文件一樣，用來打開.java文件 **/public class FileViewer extends Frame implements ActionListener {    String directory;      TextArea textarea;          public FileViewer() { this(null, null); }public FileViewer(String filename) {     this(null, filename); }        public FileViewer(String directory, String filename) {    super();  	addWindowListener(new WindowAdapter() {		public void windowClosing(WindowEvent e) { dispose(); }	    });        // 創(chuàng)建一個(gè)區(qū)域顯示文件內(nèi)容