Java

File Operation with Encrypt/Decrypt with Creating File

Write a program that allows users to encrypt and decrypt files. The 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. (For simplicity’s sake, only
alphabetical characters will be encrypted. Punctuation and other symbols will be left intact.)
Prompt the user as to whether they would like to encrypt or decrypt the file. Then prompt the user for
the file name, and perform the encryption or decryption. Output the file to a new file named
“Encrypted.txt” or “Decrypted.txt”, depending on what the user has selected to do.
HINT: Using an ArrayList to store the letters of the alphabet may simplify both encrypting and
decrypting the file


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Writer;
import java.nio.charset.Charset;

/**
*
*/

/**
* @author Rakesh Kumar Jha
* Date 12 April, 2011
* Desc - Read a file from (pass a file path), alter each character in specific fashion
* a - b
* b - c
* y - z
* z - a
*
*/
public class Assignment1 {

/**
* @param args
*/
public static void main(String[] args) throws IOException
{

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please Enter Your Choice 1. Encrypt 2. Decrypt");
int option;
String opt = null;
String fileName = null;
String fileContent=null;
String str=null;
try {
opt = br.readLine();
} catch (IOException ioe) {
System.out.println("IO error trying to read your option!");
System.exit(1);
}

System.out.println("option ="+opt);
option = Integer.parseInt(opt);
System.out.println("Option ="+option);
System.out.println("Please Enter file name (give file path)");
System.out.println("If your file name is text.txt at Desktop then your Path should be (Linux)");
System.out.println("Example - /home/rakesh/Desktop/text.txt");
System.out.println("Please Provide the file name in Window as requird");
fileName = br.readLine();

int c = 0;
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), Charset.forName("UTF-8")));
/*FileReader file = new FileReader(fileName);
BufferedReader bReader = new BufferedReader(file);*/

while((c = reader.read()) != -1) {
char character = (char) c;
System.out.println("char ="+character);
if(str==null)
{
str = String.valueOf(character);
}
else
{
str += String.valueOf(character);
}

fileContent +=str;
// fileContent.concat(str);

}
System.out.println(str+" "+fileContent);

switch(option)
{
case 1:
encrypt(str);
break;
case 2:

decrypt(str);
break;
}

}
public static void encrypt(String fileContent)
{
Writer output = null;
File file = new File("/home/rakesh/Desktop/","encrypted.txt");
String fileValue = encode(fileContent);
try {
output = new BufferedWriter(new FileWriter(file));
output.write(fileValue);
output.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
public static void decrypt(String files)
{
Writer output = null;
File file = new File("/home/rakesh/Desktop/","decrypted.txt");
String fileValue = decode(files);
try {
output = new BufferedWriter(new FileWriter(file));
output.write(fileValue);
output.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
public static String encode(String fValue)
{
String local = fValue;
System.out.println("local ="+local);
char[] charArray = local.toCharArray();

for(int i=0;i=65 && pos=97 && pos<=121)
{
char oldChar = local.charAt(i);
char newChar = (char)(pos+1);
charArray[i]= (char)(pos+1);
//local.replace(oldChar,newChar);
//local.replace(local.charAt(i),(char) (pos+1));
//replaceCharAt(local, i, (char) (pos+1));
System.out.println("local.charAt(i) ="+local.charAt(i));
System.out.println("(char) (pos+1) ="+(char) (pos+1));
}
if(pos==122)
{
char oldChar = local.charAt(i);
char newChar = (char)(97);
charArray[i]= (char)(97);
//local.replace(oldChar,newChar);
//local.replace(local.charAt(i),(char) (97));
//replaceCharAt(local, i, (char) (97));
}
}
local = String.copyValueOf(charArray);
System.out.println("local ="+local);
return local;
}
public static String decode(String fValue)
{
String local = fValue;
System.out.println("local ="+local);
char[] charArray = local.toCharArray();

for(int i=0;i=66 && pos=98 && pos<=122)
{
char oldChar = local.charAt(i);
char newChar = (char)(pos+1);
charArray[i]= (char)(pos-1);
//local.replace(oldChar,newChar);
//local.replace(local.charAt(i),(char) (pos+1));
//replaceCharAt(local, i, (char) (pos+1));
System.out.println("local.charAt(i) ="+local.charAt(i));
System.out.println("(char) (pos+1) ="+(char) (pos+1));
}
if(pos==97)
{
char oldChar = local.charAt(i);
char newChar = (char)(97);
charArray[i]= (char)(122);
//local.replace(oldChar,newChar);
//local.replace(local.charAt(i),(char) (97));
//replaceCharAt(local, i, (char) (97));
}
}
local = String.copyValueOf(charArray);
System.out.println("local ="+local);
return local;
}
/*public static String replaceCharAt(String s, int pos, char c) {
return s.substring(0,pos) + c + s.substring(pos+1);
}
*/

}


Simple Applet Program with Button handler and calling one applet to another

/**
*
*/
package guide.budha.assig2;

import java.applet.Applet;
import java.awt.ComponentOrientation;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

/**
* @author Rakesh Kumar Jha
* Date 13, April 2011
* Applet program
*
*/
public class Assignment2 extends Applet implements ActionListener{
public static boolean RIGHT_TO_LEFT = false;
int counter = 5;
public static JButton button;
public static JTextField textField;
String[] text = new String[5];
public static JTextField textField1;
public static void addComponents(Container contentPane) {
if (RIGHT_TO_LEFT)
{
contentPane.setComponentOrientation( ComponentOrientation.RIGHT_TO_LEFT);
}
button = new JButton(“OK”);
textField1 = new JTextField(“Red, Black, Yellow, Green, Blue”);
contentPane.setLayout(new FlowLayout());
contentPane.add(new JLabel(“Color “));
contentPane.add(textField1);
contentPane.add(button);
}
public static void addComponents2(Container contentPane) {
if (RIGHT_TO_LEFT)
{
contentPane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
}
button = new JButton(“OK”);
textField = new JTextField(10);
contentPane.setLayout(new FlowLayout());
contentPane.add(textField);
contentPane.add(button);
}

private static void createAndShowGUI() {
JFrame.setDefaultLookAndFeelDecorated(true);

JFrame frame = new JFrame(“Memory Game”) {
public Dimension getMinimumSize() {
Dimension prefSize = getPreferredSize();
return new Dimension(300,400);
}
};
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//Set up the content pane and components in FlowLayout
addComponents(frame.getContentPane());

frame.pack();
frame.setVisible(true);
}
public static void addComponentsFail(Container contentPane) {
if (RIGHT_TO_LEFT) {
contentPane.setComponentOrientation(
ComponentOrientation.RIGHT_TO_LEFT);
}

contentPane.setLayout(new FlowLayout());
contentPane.add(new JLabel(“Sorry! Wrong Color! Eat More Antioxidants”));

}

private static void createAndShowGUIFail() {
JFrame.setDefaultLookAndFeelDecorated(true);

JFrame frame = new JFrame(“Memory Game”) {
public Dimension getMinimumSize() {
Dimension prefSize = getPreferredSize();
return new Dimension(300,400);
}
};
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//Set up the content pane and components in FlowLayout
addComponentsFail(frame.getContentPane());

frame.pack();
frame.setVisible(true);
}
public static void addComponentsCongratulation(Container contentPane) {
if (RIGHT_TO_LEFT) {
contentPane.setComponentOrientation(
ComponentOrientation.RIGHT_TO_LEFT);
}

contentPane.setLayout(new FlowLayout());
contentPane.add(new JLabel(“Congratulations! Your memory is perfect”));

}

private static void createAndShowGUICongratulation() {
JFrame.setDefaultLookAndFeelDecorated(true);

JFrame frame = new JFrame(“Memory Game”) {
public Dimension getMinimumSize() {
Dimension prefSize = getPreferredSize();
return new Dimension(300,400);
}
};
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//Set up the content pane and components in FlowLayout
addComponentsCongratulation(frame.getContentPane());

frame.pack();
frame.setVisible(true);
}
private static void createAndShowGUI2() {
JFrame.setDefaultLookAndFeelDecorated(true);

JFrame frame = new JFrame(“Memory Game”) {
public Dimension getMinimumSize() {
Dimension prefSize = getPreferredSize();
return new Dimension(300,400);
}
};
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//Set up the content pane and components in FlowLayout
addComponents2(frame.getContentPane());

frame.pack();
frame.setVisible(true);
}

public static void main(String[] args) {
final String[] text = new String[5];//Red Black Yellow Green Blue
text[0]=”Red”;
text[1]=”Black”;
text[2]=”Yellow”;
text[3]=”Green”;
text[4]=”Blue”;
//final int counter = 0;
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
button.addActionListener(new ActionListener() {

@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
textField1.setText(“”);
createAndShowGUI2();
button.addActionListener(new ActionListener() {
int counter = 0;
@Override
public void actionPerformed(ActionEvent e) {

String getText = textField.getText().toString();
getText = getText.trim();
if(getText.equalsIgnoreCase(text[counter]))
{
textField.setText(“”);
counter++;
if(counter==5)
createAndShowGUICongratulation();

}
else
createAndShowGUIFail();

}
});
}
});
}
});
}
/* public void actionPerformed(ActionEvent e) {
if (“button”.equals(e.getActionCommand())) {
createAndShowGUI2();
} else {

}
}
*/
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
createAndShowGUI2();
}

}