Write a program that allows users to encrypt files. We will implement two simple

Question

Write a program that allows users to encrypt files. We will implement two simple encryption methods. Have the following GUI components: Have a button that when pressed opens a FileChooser. Have the user choose the file with the FileChooser. Encrypt the contents of the file and put the results in a TextArea. First Encryption Technique The first file encryption technique we will use for this program is the highly secure "one letter off" system. So an "a" will be represented by a "b", and a "b" will be represented by a "c" in the encrypted file and so on. Encrypt only the letters in the file. If you come to a non-letter character (spaces, punctuation, numbers, etc.), just print them as is without encrypting.

Explanation / Answer

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.util.Scanner;
import java.io.FileReader;
import java.io.IOException;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.filechooser.FileFilter;

public class FileChooserExample {

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

public FileChooserExample() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}

JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}

public class TestPane extends JPanel {

private JButton open;
private JTextArea textArea;
private JFileChooser chooser;

public TestPane() {
setLayout(new BorderLayout());
open = new JButton("Open");
textArea = new JTextArea(20, 40);
add(new JScrollPane(textArea));
add(open, BorderLayout.SOUTH);

open.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (chooser == null) {
chooser = new JFileChooser();
chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
chooser.setAcceptAllFileFilterUsed(false);
chooser.addChoosableFileFilter(new FileFilter() {
@Override
public boolean accept(File f) {
return f.isDirectory() || f.getName().toLowerCase().endsWith(".txt");
}

@Override
public String getDescription() {
return "Text Files (*.txt)";
}
});
}

switch (chooser.showOpenDialog(TestPane.this)) {
case JFileChooser.APPROVE_OPTION:
try (Scanner s= new Scanner(new FileReader(chooser.getSelectedFile())))
{
textArea.setText(null);
char x = s.next().charAt(0);
if(x>=65&&x<=90||x>=97&&x<=122)
{
x++;
String add=Character.toString(x);
textArea.append(add);
//commentTextArea.append(add);
}

textArea.setCaretPosition(0);
}
catch (IOException exp) {
exp.printStackTrace();
JOptionPane.showMessageDialog(TestPane.this, "Failed to read file", "Error", JOptionPane.ERROR_MESSAGE);
}
break;
}
}
});
}

}

}

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