fileioerror.java

java 基础的 一点东西,,可以看看

import java.awt.Font;
import java.awt.Color;
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.File;

class FileIOError extends JFrame
		 implements ActionListener {

   JLabel text;
   JButton button;
   JPanel panel;
   JTextField textField;
   private boolean _clickMeMode = true;

   FileIOError(){ //Begin Constructor
     text = new JLabel("Text to save to file:");
     button = new JButton("Click Me");
     button.addActionListener(this);
     textField = new JTextField(20);

     panel = new JPanel();
     panel.setLayout(new BorderLayout());
     panel.setBackground(Color.white);
     getContentPane().add(panel);
     panel.add("North", text);
     panel.add("Center", textField);
     panel.add("South", button);
   } //End Constructor

   public void actionPerformed(ActionEvent event){
     Object source = event.getSource();
     if(source == button){
       if(_clickMeMode){
        JLabel label = new JLabel();

//Write to file
        try{
		String text = textField.getText();
                byte b[] = text.getBytes();

                String outputFileName = System.getProperty("user.home", File.separatorChar + "home" + File.separatorChar + "monicap") + File.separatorChar + "text.txt";
                File outputFile = new File(outputFileName);
		FileOutputStream out = new FileOutputStream(outputFile);
		out.write(b);
		out.close();
        }catch(java.io.IOException e){
                System.out.println("Cannot write to text.txt");
        }

//Read from file
        try{
		String inputFileName = System.getProperty("user.home", File.separatorChar + "home" + File.separatorChar + "monicap") + File.separatorChar + "text.txt";
		File inputFile = new File(inputFileName); 
                FileInputStream in = new FileInputStream(inputFile);
		byte bt[] = new byte[(int)inputFile.length()];
		int i;
		i = in.read(bt);
		String s = new String(bt);
                label.setText(s);
                in.close();
	}catch(java.io.IOException e){
		System.out.println("Cannot read from text.txt");
	}
         text.setText("Text retrieved from file:");
         button.setText("Click Again");
         _clickMeMode = false;
       } else {
         text.setText("Text to save to file:");
         textField.setText("");
         button.setText("Click Me");
         _clickMeMode = true;
       }
     }
   }

   public static void main(String[] args){
     FileIO frame = new FileIO();
     frame.setTitle("Example");
     WindowListener l = new WindowAdapter() {
       public void windowClosing(WindowEvent e) {
         System.exit(0);
       }
     };

     frame.addWindowListener(l);
     frame.pack();
     frame.setVisible(true);
   }
}