encoderdecoder.java

Encoder/Decoder – Java version

   gbc.gridy = 22;
   gbc.gridwidth = 3;
   gbc.gridheight = 1;
   gbc.anchor = GridBagConstraints.CENTER;
   decodeArea = new JTextArea(7, 44);
   decodeArea.setEditable(false);
   decodeArea.setLineWrap(true);
   decodeArea.setWrapStyleWord(true);
   decodeArea.setFont(new Font("Verdana",Font.PLAIN,12));
   decodePane = new JScrollPane(decodeArea);
   getContentPane().add(decodePane, gbc);
   /* Initializes and adds a separator to the 0, 23, 3, 1 position with CENTER alignment. */
   gbc.gridx = 0; 
   gbc.gridy = 23;
   gbc.gridwidth = 3;
   gbc.gridheight = 1;
   gbc.anchor = GridBagConstraints.CENTER;
   getContentPane().add(new JSeparator(), gbc);
   /* Initializes the closeButton object and adds to it to the 0, 24, 3, 1 position with CENTER alignment. */
   gbc.gridx = 0; 
   gbc.gridy = 24;
   gbc.gridwidth = 3;
   gbc.gridheight = 1;
   gbc.anchor = GridBagConstraints.CENTER;
   closeButton = new JButton(" Close ");
   closeButton.addActionListener(this);
   getContentPane().add(closeButton, gbc);
   /*
   addWindowListener - It contains a windowClosing() method.
   windowClosing: It is called when the end user clicks the cancel button of the Window. 
   It closes the main window.
   Parameter: we- Represents the object of the WindowEvent class.
   Return Value: NA
   */
   addWindowListener(new WindowAdapter()
   {
      public void windowClosing(WindowEvent we)
      {
         System.exit(0);
      }
      }); 
      /* Initializes the object of the EncodingSchemes class. */ 
      encScheme = new EncodingSchemes(this); 
   }
   /*
   keyTyped() - This method is called when the end user enters any text in 
   the Encoded Text text area.
   Parameters: ke - Represent an object of the KeyEvent class that contains 
   the details of the event.
   Return Value: NA
   */
   public void keyTyped(KeyEvent ke)
   {
      if(ke.getSource()== textArea)
      {
         /* Enables the Encode button. */
         encodeButton.setEnabled(true);
      } 
   }
   /* Defines the abstract methods defined in the KeyListener interface. */
   public void keyPressed(KeyEvent ke){}
   public void keyReleased(KeyEvent ke){}
   /*
   actionPerformed() - This method is called when the end user clicks the any button.
   Parameters: ev – Represents an object of the ActionEvent class that contains 
   the details of the event.
   Return Value: NA
   */
   public void actionPerformed(ActionEvent ev)
   {
      /* This section is executed when the end user clicks the Select Encoding Schemes button. */
      if(ev.getSource() == selectButton)
      { 
         /* Sets the visibility of the Encoding Schemes frame to true. */
          encScheme.setVisible(true);
      }
      /* This section is executed when the end user clicks the Browse button. */
      else if(ev.getSource() == browseButton)
      {
          selectText.setText("");
          try
          {
            /* Initializes the object of the JFileChooser class. */
             jfc = new JFileChooser();
            /* Sets the file selection mode to FILES_ONLY. */
            jfc.setFileSelectionMode(JFileChooser.FILES_ONLY);
            /* Creates and sets the new file filter for selecting the text files*/
            jfc.setFileFilter(new javax.swing.filechooser.FileFilter() 
            {
               /* accept() - This method allows the user to select only text files 
               from the file chooser dialog box. 
               Parameter: f - Represents a file object.
               Return Value: boolean
               */
               public boolean accept(File f) 
               {
                  if (f.isDirectory()) 
                  {
                     return true;
                  }
                  /* Returns the file name */
                  String name = f.getName();
                  /* Checks whether the file name contains .txt or not */
                  if (name.endsWith(".txt") || name.endsWith(".TXT")) 
                  {
                     return true;
                  }
                  return false;
               }
               /* getDescription() - This method sets the file description. ]
               Parameter - NA
               Returns Value - String
               */ 
               public String getDescription() 
               {
                   return ".txt";
               }
            });
            /* Displays the Open dialog box. */
            jfc.showOpenDialog(this);
            /* Gets the file from the selected location. */
            file = jfc.getSelectedFile();
            if(file==null)
            { 
             }
             else
             {
               /* Checks the file object is a File type or Directory type. */
                if(file.isFile())
                {
                  /* Gets the absolute path of the file. */
                  str = file.getAbsolutePath();
                  /* Sets the string of absolute path to the Select File to Encode text field. */
                  selectText.setText(str);
                  /* Calls the open() method. */
                  open();
                }
                else
                {
                  /* Displays an Error message dialog box. */
                  JOptionPane.showMessageDialog(null, "You have selected an invalid file format!", "Error",JOptionPane.WARNING_MESSAGE);
                }
             }
          }
          catch(Exception e) 
          {
            System.out.println("Error" + e); 
          } 
       }
      /* This section is executed when the end user clicks the Encode button. */
       else if(ev.getSource() == encodeButton)
       {
         if (textArea.getText().equals(""))
         {
            /* Displays an Error message dialog box. */
            JOptionPane.showMessageDialog(this,"You have selected an empty file!",
            "Error", JOptionPane.WARNING_MESSAGE);
         }
         else
         {
            /* Calls the encode() method. */
             encode();
            /* Enables the Decode button. */
            decodeButton.setEnabled(true);
            /* Disables the Encode button. */
            encodeButton.setEnabled(false);
         }
      }
      /* This section is executed when the end user clicks the Decode button. */
      else if(ev.getSource()==decodeButton)
      {
         if (encodeArea.getText().equals(""))
         {
            /* Displays an Error dialog box. */
            JOptionPane.showMessageDialog(this, "The file has no content", 
            "Select another File", JOptionPane.WARNING_MESSAGE);
         }
         else
         {
            /* Calls the decode() method. */
            decode();
            /* Enables the Encode button. */
            encodeButton.setEnabled(true);
            /* Disables the Decode button. */
            decodeButton.setEnabled(false);
         } 
      }
      /* This section is executed when the end user clicks the Reset button. */
      else if(ev.getSource() == resetButton)
      {
         if(textArea.getText().equals("") && encodeArea.getText().equals("")
         && decodeArea.getText().equals("") &&
         selectText.getText().equals(""))
         {
         }
         else
         {
            /* Clears all the text areas, text field, byte buffer and char buffer. */
            textArea.setText("");
            encodeArea.setText("");
            decodeArea.setText("");
            selectText.setText("");
            buff_in.clear();
            bbuf.clear();
            cbuf.clear();
            /* Disables the Encode button. */
            encodeButton.setEnabled(false);
            /* Disables the Decode button. */
            decodeButton.setEnabled(false);
         }
      }
      /* This section is executed when the end user clicks the Close button. */
      else if(ev.getSource()==closeButton)
      {
         System.exit(0);
      }
   }
   /*
   open() - This method is invoked when the end user clicks the Browse button to open the file. 
   Parameter - NA
   Return Value - NA
   */
   public void open() 
   {
      try
      {
         /* Initializes the object of the FileInputStream class. */
         fin = new FileInputStream(file);
         /* Gets the file channel from the file input stream. */
         fchan = fin.getChannel();
         /* Gets the size of the file. */
         fsize = fchan.size();
         /* Allocates the size of the Buffer. */
         buff_in = ByteBuffer.allocate((int)fsize);
         /* Reads the buffer from the channel. */
         fchan.read(buff_in);
         /* Rewinds the data in the buffer. */
         buff_in.rewind();
         /* Stores the contents of the buff_in buffer to a string. */
         file_text = new String(buff_in.array());
         if(file_text.equals(""))
         {
            /* Displays an Error dialog box. */
            JOptionPane.showMessageDialog(null, "The file has no content", 
            "Select another File", JOptionPane.WARNING_MESSAGE);
         }
         else
         {
            /* Displays the content stored in the file_text string into Encoded Text text area. */
            textArea.setText(file_text);
            /* Enables the Encode button. */
            encodeButton.setEnabled(true);
         }
         /* Closes the file channel. */
         fchan.close();
         /* Closes the file input stream. */ 
         fin.close();
      }
      catch(IOException ioe)
      {
         System.err.println("I/O Error on Open");
      }
      catch(UnsupportedCharsetException e)
      {
         System.err.println("The File cannot be encoded");
      }
   }
   /*
   encode() - This method is invoked when the end user clicks the Encode 
   button to encode the specified text or a file.
   Parameter - NA
   Return Value - NA
   */
   public void encode()
   {
      try
      { 
         /* Initializes the object of the Charset class and sets the encoding scheme. */
         charset = Charset.forName(EncodingSchemes.encodingScheme);
         /* Initializes the object of the CharsetEncoder class. */
         encoder = charset.newEncoder();
         /* Gets the text from the Encoded Text text area. */
         String str = textArea.getText();
         /* Encodes the text and stores the encoded text in the byte buffer. */
         bbuf = encoder.encode(CharBuffer.wrap(str));
         buff_out = encoder.encode(CharBuffer.wrap(str));
         /* Creates and initializes the object of the StringBuffer class. */ 
         StringBuffer sb = new StringBuffer();
         for (int j = 0; buff_out.hasRemaining(); j++) 
         {
            /* Converts the bytes into hexadecimal string. */ 
            int b = buff_out.get();
            int ival = ((int) b) & 0xff;
            char c = (char) ival;
            sb.append(Integer.toHexString (ival));
         }
         String content = sb.toString();
         /* Clears the buff_out byte buffer. */
         buff_out.clear();
         /* Displays the encoded text in the Encoded Text text area. */
         encodeArea.setText(content); 
      }
      catch(Exception e)
      {
         System.out.println(e);
      }
   }
   /*
   decode() - This method is invoked when the end user clicks the Decode 
   button to decode the encoded text into readable format.
   Parameter - NA
   Return Value - NA
   */
   public void decode()
   {
      try
      { 
         /* Initializes the object of the CharsetDecoder class. */
         decoder = charset.newDecoder();
         /* Decodes the encoded text into a readable form and stores it into a
         character buffer. */
         cbuf = decoder.decode(bbuf); 
         /* Converts the data stored in cbuf to a string. */
         String s = cbuf.toString(); 
         /* Displays the decoded text into the Decoded Text text area. */
         decodeArea.setText(s);
         /* Clears the byte and char buffers. */
         bbuf.clear();
         cbuf.clear();
      }
      catch(Exception e)
      {
         System.out.println(e);
      } 
   }
   /*
   main() - This method creates the main window of the user interface and displays it.
   Parameters:
   args[] - Contains any command line arguments passed.
   Return Value: NA
   */
   public static void main(String[] args) 
   {
      try
      {
         /* Sets the look and feel of the Encoder/Decoder application to window look and feel. */
         UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
      }
      catch(Exception e)
      {
         System.out.println("Unknown Look and Feel." + e); 
      }
      /* Creates and initializes the object of the EncoderDecoder class. */
      EncoderDecoder ed = new EncoderDecoder();
      /* Displays the main window of the Encoder/Decoder application. */
      ed.show(); 
   }
}