JAVA Language Caesar Shift Question: Modify the Caesar class so that it will allow various sized shifts to be used, instead of just a shift of size 3. (Hint: Use an instance variable in the Caesar class to represent the shift, add a constructor to set it, and change the encode method to use it.) import java.util.*; public class TestCipher { public static void main(String[] args) { int shift = 7; Caesar caesar = new Caesar(); String text = "hello world"; String encryptTxt = caesar.encrypt(text); System.out.println(text + " encrypted with shift " + shift + " is " + encryptTxt); } } abstract class Cipher { public String encrypt(String s) { StringBuffer result = new StringBuffer(""); // Use a StringBuffer StringTokenizer words = new StringTokenizer(s); // Break s into its words while (words.hasMoreTokens()) { // For each word in s result.append(encode(words.nextToken()) + " "); // Encode it } return result.toString(); // Return the result } // encrypt() public String decrypt(String s) { StringBuffer result = new StringBuffer(""); // Use a StringBuffer StringTokenizer words = new StringTokenizer(s); // Break s into words while (words.hasMoreTokens()) { // For each word in s result.append(decode(words.nextToken()) + " "); // Decode it } return result.toString(); // Return the decryption } // decrypt() public abstract String encode(String word); // Abstract methods public abstract String decode(String word); } // Cipher class Caesar extends Cipher { public String encode(String word) { StringBuffer result = new StringBuffer(); // Initialize a string buffer for (int k = 0; k < word.length(); k++) { // For each character in word char ch = word.charAt(k); // Get the character ch = (char)('a' + (ch -'a'+ 3) % 26); // Perform caesar shift result.append(ch); // Append it to new string } return result.toString(); // Return the result as a string } // encode() public String decode(String word) { StringBuffer result = new StringBuffer(); // Initialize a string buffer for (int k = 0; k < word.length(); k++) { // For each character in word char ch = word.charAt(k); // Get the character ch = (char)('a' + (ch - 'a' + 23) % 26); // Perform reverse shift result.append(ch); // Append it to new string } return result.toString(); // Return the result as a string } // decode() } // Caesar

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Concept explainers

import java.util.*;

public class TestCipher {
public static void main(String[] args) {
int shift = 7;
Caesar caesar = new Caesar();
String text = "hello world";
String encryptTxt = caesar.encrypt(text);
System.out.println(text + " encrypted with shift " + shift + " is " + encryptTxt);
}
}

abstract class Cipher {
public String encrypt(String s) {
StringBuffer result = new StringBuffer(""); // Use a StringBuffer
StringTokenizer words = new StringTokenizer(s); // Break s into its words
while (words.hasMoreTokens()) { // For each word in s
result.append(encode(words.nextToken()) + " "); // Encode it
}
return result.toString(); // Return the result
} // encrypt()

public String decrypt(String s) {
StringBuffer result = new StringBuffer(""); // Use a StringBuffer
StringTokenizer words = new StringTokenizer(s); // Break s into words
while (words.hasMoreTokens()) { // For each word in s
result.append(decode(words.nextToken()) + " "); // Decode it
}
return result.toString(); // Return the decryption
} // decrypt()
public abstract String encode(String word); // Abstract methods
public abstract String decode(String word);
} // Cipher

class Caesar extends Cipher {

public String encode(String word) {
StringBuffer result = new StringBuffer(); // Initialize a string buffer
for (int k = 0; k < word.length(); k++) { // For each character in word
char ch = word.charAt(k); // Get the character
ch = (char)('a' + (ch -'a'+ 3) % 26); // Perform caesar shift
result.append(ch); // Append it to new string
}
return result.toString(); // Return the result as a string
} // encode()

public String decode(String word) {
StringBuffer result = new StringBuffer(); // Initialize a string buffer
for (int k = 0; k < word.length(); k++) { // For each character in word
char ch = word.charAt(k); // Get the character
ch = (char)('a' + (ch - 'a' + 23) % 26); // Perform reverse shift
result.append(ch); // Append it to new string
}
return result.toString(); // Return the result as a string
} // decode()
} // Caesar