Question

I am having an issue with trying to make my code to have a required output

////////////Input//////////

With computer science, you can work in any industry.
0

//////////Output//////////

Required Output

Enter some text to encrypt\n
Enter a key\n
Error: Key is divisible by 26. That's a bad key!\n
Useless key: 0\n

///////////Cipher.java///////// ------------ My code.

public class Cipher
{
    private String plainText;
    private int key;

    public Cipher(String text, int key) throws EmptyPlainText, UselessKeyException
    {
        if (text == null || text.length() == 0)
        {
            throw new EmptyPlainText("Error: Nothing to encrypt!");
        }
        if (key % 26 == 0)
        {
            throw new UselessKeyException(26, "Error: Key is divisible by 26. That's a bad key!");
        }

        this.plainText = text;
        this.key = key;
    }

    public String getPlainText()
    {
        return plainText;
    }

    public int getKey()
    {
        return key;
    }

    public String getCipherText()
    {
        String cipher = "";
        int k = key % 26;
        char c;
        int integer;

        for (int counter = 0; counter < plainText.length(); counter++)
        {
            c = plainText.charAt(counter);
            if (Character.isUpperCase(c))
            {
                integer = c - 'A';
                integer += k;
                integer %= 26;
                c = (char) (integer + 'A');
            } else if (Character.isLowerCase(c))
            {
                integer = c - 'a';
                integer += k;
                integer %= 26;
                c = (char) (integer + 'a');
            } else
                c += k;

            cipher += c;
        }
        return cipher;
    }
}

///////////CipherDemo/////////

import java.util.Scanner;

public class CipherDemo {
    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Enter some text to encrypt");
        String input = keyboard.nextLine();
        System.out.println("Enter a key");
        int key = keyboard.nextInt();

        try {
            Cipher c = new Cipher(input, key);
            System.out.println("Plain text: " + c.getPlainText());
            System.out.println("Cipher text: " + c.getCipherText());
            System.out.println("Key: " + c.getKey());
        } catch (EmptyPlainText e) {
            System.out.println(e.getMessage());
        } catch (UselessKeyException e) {
            System.out.println(e.getMessage());
            System.out.println("Useless key: " + e.getUselessKey());
        }
    }
}

Answer 1

//Java code

public class EmptyPlainText extends Exception {
   String message;
    public EmptyPlainText()
    {
        super();
        message ="";
    }
    public EmptyPlainText(String message)
    {
        super(message);
    }

    @Override
    public String getMessage() {
        return message;
    }
}

//======================================

public class UselessKeyException extends Exception {
    String message;
    int uselessKey;
    public UselessKeyException()
    {
        super();
        message ="";
        uselessKey=0;
    }
    public UselessKeyException(int uselessKey,String message)
    {
        this.message = message;
        this.uselessKey = uselessKey;
    }

    @Override
    public String getMessage() {
        return message;
    }

    public int getUselessKey() {
        return uselessKey;
    }

    @Override
    public synchronized Throwable getCause() {
        return super.getCause();
    }
}

//=====================================

public class Cipher
{
    private String plainText;
    private int key;

    public Cipher(String text, int key) throws EmptyPlainText, UselessKeyException
    {
        if (text == null || text.length() == 0)
        {
            throw new EmptyPlainText("Error: Nothing to encrypt!");
        }
        if (key % 26 == 0)
        {
            throw new UselessKeyException(key , "Error: Key is divisible by 26. That's a bad key!");
        }

        this.plainText = text;
        this.key = key;
    }

    public String getPlainText()
    {
        return plainText;
    }

    public int getKey()
    {
        return key;
    }

    public String getCipherText()
    {
        String cipher = "";
        int k = key % 26;
        char c;
        int integer;

        for (int counter = 0; counter < plainText.length(); counter++)
        {
            c = plainText.charAt(counter);
            if (Character.isUpperCase(c))
            {
                integer = c - 'A';
                integer += k;
                integer %= 26;
                c = (char) (integer + 'A');
            } else if (Character.isLowerCase(c))
            {
                integer = c - 'a';
                integer += k;
                integer %= 26;
                c = (char) (integer + 'a');
            } else
                c += k;

            cipher += c;
        }
        return cipher;
    }
}

//==============================

import java.util.Scanner;

public class CipherDemo {
    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Enter some text to encrypt");
        String input = keyboard.nextLine();
        System.out.println("Enter a key");
        int key = keyboard.nextInt();

        try {
            Cipher c = new Cipher(input, key);
            System.out.println("Plain text: " + c.getPlainText());
            System.out.println("Cipher text: " + c.getCipherText());
            System.out.println("Key: " + c.getKey());
        } catch (EmptyPlainText e) {
            System.out.println(e.getMessage());
        } catch (UselessKeyException e) {
            System.out.println(e.getMessage());
            System.out.println("Useless key: " + e.getUselessKey());
        }
    }
}

//Output

//If you need any help regarding this solution ........... please leave a comment ..... thanks

"C:\Program Files\Javaljdk1.8.0_221\bin\java.exe" ... Enter some text to encrypt Java Enter a key Error: Key is divisible by 26. That's a bad key! Useless key: 26 Process finished with exit code 0