Question

Write a program names EncryptDecrypt.java that has the following menu choices: Print menu and allow user to choose options. The program must have a file dialogue box for text file. Output should be based on user choices.

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6. Read in an encrypted file
7. Decrypt the file
8. Write out the decrypted file to the console
9. End

Your encryption program should work like a filter, reading the contents of one file modifying the data into a code, and then writing the coded contents out to a second file. Do not hard code the path location! Use a simple one from the shift category encryption technique. Do not use a serialized file use a text file.

Answer 1

Screenshot

Program

/**
* Program to read and write file and encrypt decrypt data
* Here user get options for different operations
* Read user specified data encode or decode as per the requirements
*/
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

public class EncryptDecrypt {
   public static void main(String[] args) {
       //Variable for data
       String data="",encrypt="",decrypt="";
       //User options
       int opt=menu();
       //Loop until exit
       while(opt!=9) {
           //Read a file specified by user and store into data
           if(opt==1) {
               data=readFile();
           }
           //Print data value
           else if(opt==2) {
               printData(data);
           }
           //Encrypt data value and display encrypted on console
           else if(opt==3) {
               encrypt=encryptData(data);
               System.out.println("\nEncrypted Data: ");
               printData(encrypt);
           }
           //Write encrypted data into user specified file
           else if(opt==4) {
               writeEncrypt(encrypt);
               System.out.println("\nSuccessfully wrote encrypted data!!");
           }
           //Clear data
           else if(opt==5) {
               data=null;
               encrypt=null;
               decrypt=null;
               System.out.println("\nClear memory of data value!!!");
           }
           //Read a file data for decryption
           else if(opt==6) {
               data=readFile();
           }
           //Decrypt
           else if(opt==7) {
               decrypt=decryptData(data);
               System.out.println("\nDecryption completed");
           }
           //Display decrypted information
           else if(opt==8) {
               System.out.println("\nDecrypted data: ");
               printData(decrypt);
           }
           opt=menu();
       }
       System.out.println("\nExiting Program............");
   }
   //Get menu
   //Show options and prompt for input
   //Error check and return opt
   public static int menu() {
       Scanner sc=new Scanner(System.in);
       System.out.println("USER OPTIONS:");
       System.out.println("\r\n" +
               "1. Read in a file\r\n" +
               "2. Print the file to the console\r\n" +
               "3. Encrypt the file and write it to the console\r\n" +
               "4. Write out the encrypted file to a text file\r\n" +
               "5. Clear the data in memory\r\n" +
               "6.   Read in an encrypted file\r\n" +
               "7.   Decrypt the file\r\n" +
               "8.   Write out the decrypted file to the console\r\n" +
               "9.   End\r\n" +
               "");
       System.out.println("Enter your choice: ");
       int opt=sc.nextInt();
       while(opt<1 || opt>9) {
           System.out.println("Error!!!Option should be 1-9.Pease re-enter");
           System.out.println("Enter your choice: ");
           opt=sc.nextInt();
       }
       sc.nextLine();
       return opt;
   }
   //Read data from file and return string of data
   public static String readFile() {
       Scanner sc=new Scanner(System.in);
       StringBuffer data=new StringBuffer();
       System.out.println("\nEnter file name to read: ");
       String filename=sc.nextLine();
       try {
           Scanner sc1=new Scanner(new File(filename));
           while(sc1.hasNextLine()) {
               data.append(sc1.nextLine()+"\n");
           }
       } catch (FileNotFoundException e) {
           e.printStackTrace();
       }
       return data.toString();
   }
   //Display passed data on console
   public static void printData(String str) {
       System.out.println("\n"+str);
   }
   //Encrypt data using simple shift add method
   //Check each character , if alphebet add with shift value
   //Here i take fixed shift value
   public static String encryptData(String data) {
       char ch;
       int shift =5;
        String encrypt = "";
        for(int i=0; i < data.length();i++)
        {
            ch = data.charAt(i);
            if(ch >= 'a' && ch <= 'z')
            {
             ch = (char) (ch + shift);
             if(ch> 'z') {
                ch = (char) (ch+'a'-'z'-1);
             }
             encrypt = encrypt + ch;
            }
          
            else if(ch >= 'A' && ch <= 'Z') {
             ch = (char) (ch + shift);  
             if(ch > 'Z') {
                 ch = (char) (ch+'A'-'Z'-1);
             }
             encrypt = encrypt + ch;
            }
            else {
             encrypt = encrypt +ch;
            }
        }
        return encrypt;
   }
   //Write encrypted data into user specified file
   public static void writeEncrypt(String data) {
       Scanner sc=new Scanner(System.in);
       System.out.println("\nEnter file name to write encrypted data: ");
       String filename=sc.nextLine();
       try {
           FileWriter fw=new FileWriter(filename);
           fw.write(data);
           fw.close();
       } catch (IOException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
   }
   //Decrypt data using simple shift sub method
   //Check each character , if alphebet subtract with shift value
   //Here i take fixed shift value
   public static String decryptData(String data) {
       char ch;
       int shift =5;
        String decrypt = "";
       for(int i=0; i < data.length();i++)

        {
             ch = data.charAt(i);
            if(ch >= 'a' && ch <= 'z')
            {
                ch = (char) (ch - shift);
                if(ch < 'a') {
                    ch = (char) (ch-'a'+'z'+1);
                }
                decrypt= decrypt + ch;
            }  
            else if(ch >= 'A' && ch <= 'Z')
            {
                ch = (char) (ch - shift);
                if (ch < 'A') {
                    ch = (char) (ch-'A'+'Z'+1);
                }
                decrypt= decrypt +ch;          
            }
            else
            {
             decrypt = decrypt +ch;          
            }
        }
       return decrypt;
   }
}

---------------------------------------------------

Output

USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
1

Enter file name to read:
datafile.txt
USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
2

Your encryption program should work like a filter, reading the contents of one file modifying
the data into a code, and then writing the coded contents out to a second file.

USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
3

Encrypted Data:

Dtzw jshwduynts uwtlwfr xmtzqi btwp qnpj f knqyjw, wjfinsl ymj htsyjsyx tk tsj knqj rtinkdnsl
ymj ifyf nsyt f htij, fsi ymjs bwnynsl ymj htiji htsyjsyx tzy yt f xjhtsi knqj.

USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
4

Enter file name to write encrypted data:
encryptedfile.txt

Successfully wrote encrypted data!!
USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
5

Clear memory of data value!!!
USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
2

null
USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
6

Enter file name to read:
encryptedfile.txt
USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
7

Decryption completed
USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
8

Decrypted data:

Your encryption program should work like a filter, reading the contents of one file modifying
the data into a code, and then writing the coded contents out to a second file.

USER OPTIONS:

1. Read in a file
2. Print the file to the console
3. Encrypt the file and write it to the console
4. Write out the encrypted file to a text file
5. Clear the data in memory
6.   Read in an encrypted file
7.   Decrypt the file
8.   Write out the decrypted file to the console
9.   End

Enter your choice:
9

Exiting Program............

------------------------------------------------------

Note:-

I assume you are expecting this way