构造函数参数值未实现

Question

I'm creating a very simple encoder that will shuffle the characters in a string. I've written it to split this string in half, forming two new variables. The user chooses the number of shuffles they want and that is passed as a parameter in the new class constructor -- which should then use that shuffle value throughout the class. Mine is not. The shuffleEncryption method is using the class variable, 0, instead. I know this must be something very obvious, but I am not catching it. :/

//From Main Class

        System.out.println("Enter message to encrypt: ");
        String message = input.next();
        System.out.print("Number of shuffles: " );
        int numShuffles = input.nextInt();
        ShuffleCipher shuffle = new ShuffleCipher(numShuffles);
        System.out.println(shuffle.encode(message));

//The shuffle class

public class ShuffleCipher implements MessageEncoder {
int shuffle;

public ShuffleCipher(int shuffle) {
    shuffle = this.shuffle;     
}

private String shuffleEncryption(String str) {
   int middle = str.length()/2;
   int loop = 1;
   System.out.println("shift" + shuffle);
   StringBuilder sb = new StringBuilder();

   do {
        String firstHalf = str.substring(0, middle);
        System.out.println("first:" + firstHalf);
        String secondHalf = str.substring(middle);
        System.out.println("second:" + secondHalf);

        for(int i = 0, j = 0; i < firstHalf.length(); i++, j++) {
            sb = sb.append(secondHalf.charAt(i));

           if(j < secondHalf.length()) {
           sb = sb.append(firstHalf.charAt(i));           
       }
       str = sb.toString();
   }
   loop++;
   } while (loop <= shuffle);

    return str;
 } 

@Override
public String encode(String plainText) {
    String shuffled; 
    shuffled = shuffleEncryption(plainText);
    return shuffled;
 }
}

Answer 1

You are not setting the shuffle member variable in the constructor.

Change this:-

public ShuffleCipher(int shuffle) {
    shuffle = this.shuffle;     
}

to this:-

public ShuffleCipher(int shuffle) {
    this.shuffle = shuffle;     
}