//  NewTextFileApplication.java  (c) 2006 Kari Laitinen

//  2006-02-01  File created.
//  2006-02-02  Last modification.

//  This is a Java Application that demonstrates:

//    - the use of a JTextArea object
//    - storing text lines to a text file

import java.awt.* ;
import java.awt.event.* ;
import javax.swing.* ;
import javax.swing.event.* ;
import java.io.* ;    //  Classes for file handling.


class NewTextFileFrame extends JFrame
                       implements DocumentListener, ActionListener,
                                  WindowListener
{
   public static final int FRAME_WIDTH   =  500 ;
   public static final int FRAME_HEIGHT  =  400 ;

   JTextArea   writing_area ;
   JLabel      file_name_label ;
   JTextField  file_name_field ;
   JButton     save_button ;

   boolean  text_has_to_be_saved_to_file  =  false ;

   public NewTextFileFrame()
   {
      setTitle( "CREATE A NEW TEXT FILE" ) ;
      setSize( FRAME_WIDTH, FRAME_HEIGHT ) ;
      setBackground( Color.white ) ;

      setLayout( new BorderLayout() ) ;

      writing_area  =  new  JTextArea( 20, 60 ) ;
      writing_area.getDocument().addDocumentListener( this ) ;
      add( "Center", writing_area ) ;

      file_name_label  =  new  JLabel( " File name:" ) ;

      file_name_field  =  new  JTextField( "tmp.txt", 20 ) ;
      file_name_field.getDocument().addDocumentListener( this ) ;

      save_button  =  new  JButton( "Save" ) ;
      save_button.setEnabled( false ) ;
      save_button.addActionListener( this ) ;

      JPanel  operations_panel  =  new  JPanel() ;

      operations_panel.add( file_name_label ) ;
      operations_panel.add( file_name_field ) ;
      operations_panel.add( save_button ) ;

      add( "South", operations_panel ) ;

      addWindowListener( this ) ;

      //  When the default close operation is DO_NOTHING_ON_CLOSE
      //  the windowClosing() method determines what actually happens
      //  when the window is being closed.

      setDefaultCloseOperation( JFrame.DO_NOTHING_ON_CLOSE ) ;

   }



   void process_document_event( DocumentEvent event )
   {
      if ( event.getDocument()  ==  file_name_field.getDocument() )
      {
         //  The file name field was modified. It is required that
         //  the length of the file name is at least 5 characters,
         //  and the file name extension is .txt

         if ( file_name_field.getText().length() <  5  ||
              ! file_name_field.getText().endsWith( ".txt" ) )
         {
            file_name_label.setText( "INVALID FILE NAME: " ) ;
         }
         else
         {
            file_name_label.setText( "        File name:" ) ;
         }
      }
      else if ( event.getDocument()  ==  writing_area.getDocument() )
      {
         save_button.setEnabled( true ) ;
         text_has_to_be_saved_to_file  =  true ;
      }
   }

   public void insertUpdate( DocumentEvent event )
   {
      process_document_event( event ) ;
   }

   public void removeUpdate( DocumentEvent event )
   {
      process_document_event( event ) ;
   }

   public void changedUpdate( DocumentEvent event )
   {
   }  //  This kind of update is not possible in the case of JTextField


   public void actionPerformed( ActionEvent event )
   {
      if ( event.getSource()  ==  save_button  &&
           ! file_name_label.getText().contains( "INVALID" ) )
      {

         String file_name  =  file_name_field.getText() ;
   
         try
         {
            PrintWriter new_text_file  =  new PrintWriter(
                                                new FileWriter( file_name ) ) ;
   
            writing_area.write( new_text_file ) ;
   
            new_text_file.close() ;
            save_button.setEnabled( false ) ;
            text_has_to_be_saved_to_file  =  false ;   
         }
         catch ( IOException  caught_io_exception )
         {
            System.out.print( "\n\n  File error. Cannot write to \""
                              +  file_name + "\".\n" ) ;
         }
      }
   }


   public void windowClosing( WindowEvent event )
   {
      //  If the text on the writing area has not been saved after
      //  last modification, window closing operation will not be
      //  permitted.

      if ( text_has_to_be_saved_to_file  ==  false )
      {
         setVisible( false ) ;
         System.exit( 0 ) ;
      }
   }

   //  Other methods required by the WindowListener interface:
   public void windowActivated( WindowEvent event ) {}
   public void windowClosed( WindowEvent event ) {}
   public void windowDeactivated( WindowEvent event ) {}
   public void windowDeiconified( WindowEvent event ) {}
   public void windowIconified( WindowEvent event ) {}
   public void windowOpened( WindowEvent event ) {}
}



public class NewTextFileApplication
{
   public static void main( String[] not_in_use )
   {
      NewTextFileFrame  new_text_file_frame  =  new  NewTextFileFrame() ;

      new_text_file_frame.setVisible( true ) ;
   }
}


/****

   NOTES:

   One way to store the text from the writing area to a file
   is to use the following statements, but these statements do not produce
   correct line termination characters OD and 0A in Windows.


         PrintWriter output_file  =  new PrintWriter(
                                             new FileWriter( file_name ) ) ;

         String  text_from_writing_area  =  writing_area.getText() ;

         output_file.print( text_from_writing_area ) ;

         output_file.close() ;


   Another correct way to store the text lines would be to exploit
   the Scanner class and println() method in the following way:

         PrintWriter new_text_file  =  new PrintWriter(
                                             new FileWriter( file_name ) ) ;

         java.util.Scanner  text_to_file  =  new java.util.Scanner(

                            writing_area.getText() ) ;

         while( text_to_file.hasNextLine() )
         {
            String text_line_to_file  =  text_to_file.nextLine() ;
 
            new_text_file.println( text_line_to_file ) ;
         }


         new_text_file.close() ;


****/