My fellow students and I have been struggling to comprehend this lesson given to us over this break. The project's description is as follows:

You have just been hired by the CIA as a programmer in the encryption department. Your job is
to write a class called Crypto. One method, encrypt, will accept a String that represents the
sentence to be encrypted. It will return a String that is the sentence with all v’s (big or small)
replaced with “ag’,r”, all m’s (big or small) with “ssad”, all g’s (big or small) with “jeb..w”, and
all b’s (big or small) with “dug>?/”.

There are two classes: Crypto and Tester. Tester is given as:

import java.io.*;
import java.util.*;
public class Tester
{
public static void main(String args[])
{
Scanner kbReader = new Scanner(System.in);
System.out.print(“Enter a sentence that is to be encrypted: ”);
String sntnc = kbReader.nextLine( );
System.out.println(“Original sentence = ” + sntnc);
Crypto myCryptObj = new Crypto( );
String encryptdSntnc = myCryptObj.encrypt(sntnc);
System.out.println(“Encrypted sentence = ” + encryptdSntnc);
String decryptdSntnc = myCryptObj.decrypt(encryptdSntnc);
System.out.println(“Decrypted sentence = ” + decryptdSntnc);
}
}

While the progress I have made on Crypto is:

class Crypto
{
private String sntnc;
public String Crypto (String sntnc)
{
String x = sntnc;
return x;
}
public String encrypt(String sntnc)
{
String finalSntnc = "";

for(int y = 0; y < sntnc.length( ); y++)
{
char nextChar = sntnc.charAt(y);
switch (nextChar)
{
case 'v':
case 'V':
{
finalSntnc = finalSntnc + "ag\',r";
break;
}

case 'm':
case 'M':
{
finalSntnc = finalSntnc +"saad";
break;
}
case 'g':
case 'G':
{
finalSntnc = finalSntnc + "jeb..w";
break;
}

case 'b':
case 'B':
{
finalSntnc = finalSntnc + "dug>?/";
break;
}

default:
{
finalSntnc = finalSntnc + nextChar;
}
}


}
return finalSntnc;
}

I am stuck and can't seem to finish the project. Is there anyone that can help me?