// Fig. 17.6: ReadSequentialFile.java
// This program reads a file of objects sequentially
// and displays each record.
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import com.deitel.jhtp3.ch17.*;

public class ReadSequentialFile extends JFrame {
   private ObjectInputStream input;
   private BankUI userInterface;
   private JButton nextRecord, open;

   // Constructor -- initialize the Frame 
   public ReadSequentialFile()
   {
      super( "Reading a Sequential File of Objects" );

      getContentPane().setLayout( new BorderLayout() );
      userInterface = new BankUI();
      nextRecord = userInterface.getDoTask();
      nextRecord.setText( "Next Record" );
      nextRecord.setEnabled( false );  
 
      nextRecord.addActionListener(
         new ActionListener() {
            public void actionPerformed( ActionEvent e )
            {               
               readRecord();
            }
         }
      );
 
      addWindowListener(
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
            {
               if ( input != null )
                  closeFile();

               System.exit( 0 );
            }
         }
      ); 
      open = userInterface.getDoTask2();

      open.setText( "Open File" );
      open.addActionListener(
         new ActionListener() {
            public void actionPerformed( ActionEvent e )
            {
               openFile();
            }
         }
      );
      
      getContentPane().add( userInterface, 
                            BorderLayout.CENTER );
      pack();
      setSize( 300, 200 );
      show();
   }

   private void openFile()
   {
      JFileChooser fileChooser = new JFileChooser();

      fileChooser.setFileSelectionMode(
         JFileChooser.FILES_ONLY );
      int result = fileChooser.showOpenDialog( this );
 
      // user clicked Cancel button on dialog
      if ( result == JFileChooser.CANCEL_OPTION )
         return;

      File fileName = fileChooser.getSelectedFile();
 
      if ( fileName == null ||
           fileName.getName().equals( "" ) )
         JOptionPane.showMessageDialog( this,
            "Invalid File Name",
            "Invalid File Name",
            JOptionPane.ERROR_MESSAGE );
      else {
         // Open the file
         try {
            input = new ObjectInputStream(
                        new FileInputStream( fileName ) );
            open.setEnabled( false );
            nextRecord.setEnabled( true );
         }
         catch ( IOException e ) {
            JOptionPane.showMessageDialog( this,
               "Error Opening File", "Error",
               JOptionPane.ERROR_MESSAGE );
         }      
      }
   }

   public void readRecord()
   {
      BankAccountRecord record;

      // input the values from the file
      try {
         record = ( BankAccountRecord ) input.readObject();
         String values[] = {
            String.valueOf( record.getAccount() ),
            record.getFirstName(),
            record.getLastName(),
            String.valueOf( record.getBalance() ) };
         userInterface.setFieldValues( values );
      }
      catch ( EOFException eofex ) {
         nextRecord.setEnabled( false );
         JOptionPane.showMessageDialog( this,
            "No more records in file",
            "End of File", JOptionPane.ERROR_MESSAGE );
      }
      catch ( ClassNotFoundException cnfex ) {
         JOptionPane.showMessageDialog( this,
            "Unable to create object",
            "Class Not Found", JOptionPane.ERROR_MESSAGE );
      }
      catch ( IOException ioex ) {
         JOptionPane.showMessageDialog( this,
            "Error during read from file",
            "Read Error", JOptionPane.ERROR_MESSAGE );
      }
   }

   private void closeFile()
   {
      try {
         input.close();
         System.exit( 0 );
      }
      catch ( IOException e ) {
         JOptionPane.showMessageDialog( this,
            "Error closing file",
            "Error", JOptionPane.ERROR_MESSAGE );
         System.exit( 1 );
      }
   }

   public static void main( String args[] )
   {
      new ReadSequentialFile();
   }
}

/**************************************************************************
 * (C) Copyright 1999 by Deitel & Associates, Inc. and Prentice Hall.     *
 * All Rights Reserved.                                                   *
 *                                                                        *
 * DISCLAIMER: The authors and publisher of this book have used their     *
 * best efforts in preparing the book. These efforts include the          *
 * development, research, and testing of the theories and programs        *
 * to determine their effectiveness. The authors and publisher make       *
 * no warranty of any kind, expressed or implied, with regard to these    *
 * programs or to the documentation contained in these books. The authors *
 * and publisher shall not be liable in any event for incidental or       *
 * consequential damages in connection with, or arising out of, the       *
 * furnishing, performance, or use of these programs.                     *
 *************************************************************************/