本人是Java初学者，今天做书上一例题，遇到问题(参见java源码)：定义MyWindow类时，类名MyWindow下出现黄色波浪线，单击左侧“灯泡”，提示“The serializable class MyWindow does not declare a static final serialVersionUID field of type long Test.java ”，不知如何修改，特此请教。
另，按“运行”键，程序也能运行，但屏幕上没有变化，不显示新窗口。
- Java code
/*例9.3(P179) 说明BufferedWriter类用法的应用程序*/import java.io.*;import java.awt.*;import javax.swing.*;import java.awt.event.*;class MyWindow extends JFrame implements ActionListener{ JTextArea text; JButton button; FileWriter writefile; BufferedWriter out; MyWindow() { super("缓冲式样流的输出"); Container con=this.getContentPane();//获得内容面板 text=new JTextArea(20,30); text.setBackground(Color.cyan); button=new JButton("写文件"); button.addActionListener(this); con.setLayout(new BorderLayout()); con.setSize(40,40); con.setVisible(true); con.add(text,"Center"); con.add(button, "South"); try { writefile=new FileWriter("d:\\file2.txt"); out=new BufferedWriter(writefile); } catch(IOException e) {} } public void actionPerformed(ActionEvent e) { if(e.getSource()==button) //将文本区内容采用缓冲式输出到文件 {try { out.write(text.getText(),0,(text.getText()).length()); out.flush(); text.setText(null); System.exit(0); } catch (IOException exp) { text.setText("文件写出错!\n"); System.exit(-1); } } }}public class Test{ public static void main(String args[]) { MyWindow myWin=new MyWindow(); myWin.pack(); }}------解决方案--------------------
黄色的是警告，可以不用管它
------解决方案--------------------
------解决方案--------------------
myWin.setVisible(true);
------解决方案--------------------
- Java code
import java.io.*;import java.awt.*;import javax.swing.*;import java.awt.event.*;class MyWindow extends JFrame implements ActionListener{ static final long serialVersionUID=1L; JTextArea text; JButton button; FileWriter writefile; BufferedWriter out; MyWindow() { super("缓冲式样流的输出"); Container con=this.getContentPane();//获得内容面板 text=new JTextArea(20,30); text.setBackground(Color.cyan); button=new JButton("写文件"); button.addActionListener(this); con.setLayout(new BorderLayout()); con.setSize(40,40); con.setVisible(true); con.add(text,"Center"); con.add(button, "South"); try { writefile=new FileWriter("d:\\file2.txt"); out=new BufferedWriter(writefile); } catch(IOException e) { e.printStackTrace(); } } public void actionPerformed(ActionEvent e) { if(e.getSource()==button) //将文本区内容采用缓冲式输出到文件 {try { out.write(text.getText(),0,(text.getText()).length()); out.flush(); text.setText(null); System.exit(0); } catch (IOException exp) { text.setText("文件写出错!\n"); System.exit(-1); } } }}public class Test2{ public static void main(String args[]) { MyWindow myWin=new MyWindow(); myWin.pack(); myWin.setVisible(true); myWin.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); }}