import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

/**
Illustrates several things about file handling in Java.
@author Melvin Fitting
@version April, 2003
*/

public class ReadWriteFile extends JFrame implements ActionListener
{
   private JButton readButton, writeButton;

   public static void main(String[] args)
   {
      ReadWriteFile rwf = new ReadWriteFile();
   }

   public ReadWriteFile()
   {
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setTitle("File reading/writing demo");
      getContentPane().setLayout(new FlowLayout());
      writeButton = new JButton("Write to a file");
      writeButton.addActionListener(this);
      getContentPane().add(writeButton);
      readButton = new JButton("Read from a file");
      readButton.addActionListener(this);
      getContentPane().add(readButton);
      setSize(400,300);
      setVisible(true);
   }

   public void actionPerformed(ActionEvent e)
   {
      if (e.getSource()==readButton)
      {
         StringBuffer sb = new StringBuffer();
         try
         {
            JFileChooser fc = new JFileChooser();
            int returnVal = fc.showOpenDialog(this);
            if (returnVal == JFileChooser.APPROVE_OPTION)
            {
               File datafile = fc.getSelectedFile();
               DataInputStream infile =
                  new DataInputStream(new FileInputStream(datafile));
               try
               {
                  while(true)
                     sb.append(infile.readUTF() + " ");
               }
               catch(EOFException eof)
               {
                  infile.close();
               }
            }
         }
         catch(IOException ex1)
         {System.out.println("IO error");}
         getContentPane().removeAll();
         getContentPane().add(writeButton);
         getContentPane().add(readButton);
         JTextArea result = new JTextArea(sb.toString());
         result.setLineWrap(true);
         result.setWrapStyleWord(true);
         result.setSize(250,400);
         result.setEditable(false);
         getContentPane().add(result);
         validate();
      }
      else if (e.getSource()==writeButton)
      {
         try
         {
            JFileChooser fc = new JFileChooser();
            int returnVal = fc.showSaveDialog(this);
            if (returnVal == JFileChooser.APPROVE_OPTION)
            {
               File datafile = fc.getSelectedFile();
               DataOutputStream outfile =
                  new DataOutputStream(new FileOutputStream(datafile));
               boolean finished = false;
               do
               {
                  String word = JOptionPane.showInputDialog("Enter a string.  Enter nothing, to stop.");
                  if (word.length()>0) outfile.writeUTF(word);
                  else finished = true;
               }while(!finished);
               outfile.close();
            }
         }
         catch(IOException ex2)
         {System.out.println("IO Error");}
      }
   }
}