import java.awt.*; import java.io.*; import java.awt.datatransfer.*; import java.awt.event.*;   public class Main extends Frame implements ActionListener {         private static final long serialVersionUID = 1L; TextArea textArea = new TextArea();    MenuBar menuBar = new MenuBar();    Menu fileMenu = new Menu("File");    MenuItem newItem = new MenuItem("New");    MenuItem openItem = new MenuItem("Open");    MenuItem saveItem = new MenuItem("Save");    MenuItem saveAsItem = new MenuItem("Save As");    MenuItem exitItem = new MenuItem("Exit");    Menu editMenu = new Menu("Edit");    MenuItem selectItem = new MenuItem("Select All");    MenuItem copyItem = new MenuItem("Copy");    MenuItem cutItem = new MenuItem("Cut");    MenuItem pasteItem = new MenuItem("Paste");    String fileName = null;    Toolkit toolKit=Toolkit.getDefaultToolkit();    Clipboard clipBoard=toolKit.getSystemClipboard();         private FileDialog openFileDialog = new FileDialog(this,"Open File",FileDialog.LOAD);     private FileDialog saveAsFileDialog = new FileDialog(this,"Save File As",FileDialog.SAVE);     public Main(){     setTitle("记事本程序-by Jackbase");     setFont(new Font("Times New Roman",Font.PLAIN,12));     setBackground(Color.white);     setSize(400,300);     fileMenu.add(newItem);     fileMenu.add(openItem);     fileMenu.addSeparator();     fileMenu.add(saveItem);     fileMenu.add(saveAsItem);     fileMenu.addSeparator();     fileMenu.add(exitItem);     editMenu.add(selectItem);     editMenu.addSeparator();     editMenu.add(copyItem);     editMenu.add(cutItem);     editMenu.add(pasteItem);     menuBar.add(fileMenu);     menuBar.add(editMenu);     setMenuBar(menuBar);     add(textArea);     addWindowListener(new WindowAdapter(){                       public void windowClosing(WindowEvent e){                           System.exit(0);                         }                       });     newItem.addActionListener(this);     openItem.addActionListener(this);     saveItem.addActionListener(this);     saveAsItem.addActionListener(this);     exitItem.addActionListener(this);     selectItem.addActionListener(this);     copyItem.addActionListener(this);     cutItem.addActionListener(this);     pasteItem.addActionListener(this);   }     public void actionPerformed(ActionEvent e) {  //监听事件     Object eventSource = e.getSource();     if(eventSource == newItem){       textArea.setText("");     }else if(eventSource == openItem){       openFileDialog.show();       fileName = openFileDialog.getDirectory()+openFileDialog.getFile();       if(fileName != null)         readFile(fileName);     }else if (eventSource == saveItem){       if(fileName != null)         writeFile(fileName);     }else if(eventSource == saveAsItem){       saveAsFileDialog.show();       fileName = saveAsFileDialog.getDirectory()+saveAsFileDialog.getFile();       if (fileName!= null)         writeFile(fileName);     }else if(eventSource == selectItem){        textArea.selectAll();     }else if(eventSource == copyItem){        String text=textArea.getSelectedText();        StringSelection selection=new StringSelection(text);        clipBoard.setContents(selection,null);     }else if(eventSource == cutItem){        String text=textArea.getSelectedText();        StringSelection selection=new StringSelection(text);        clipBoard.setContents(selection,null);        textArea.replaceRange("",textArea.getSelectionStart(),textArea.getSelectionEnd());     }else if(eventSource == pasteItem){        Transferable contents=clipBoard.getContents(this);        if(contents==null) return;        String text;        text="";        try{             text=(String)contents.getTransferData(DataFlavor.stringFlavor);         }catch(Exception exception){         }        textArea.replaceRange(text,textArea.getSelectionStart(),textArea.getSelectionEnd());     }else if(eventSource == exitItem){       System.exit(0);     }   }     public void readFile(String fileName){ //读取文件处理     try{       File file = new File(fileName);       FileReader readIn = new FileReader(file);       int size = (int)file.length();       int charsRead = 0;       char[] content = new char[size];       while(readIn.ready())         charsRead += readIn.read(content, charsRead, size - charsRead);       readIn.close();       textArea.setText(new String(content, 0, charsRead));     }     catch(IOException e){       System.out.println("Error opening file");     }   }     public void writeFile(String fileName){  //写入文件处理     try{       File file = new File (fileName);       FileWriter writeOut = new FileWriter(file);       writeOut.write(textArea.getText());       writeOut.close();     }     catch(IOException e){       System.out.println("Error writing file");     }   }       @SuppressWarnings("deprecation")         public static void main(String[] args){       Frame frame = new Main(); //创建对象       frame.show();   //是对象显示    } }