String Reverse using XOR

Better implementation of string reverse is by using XOR operation. This eliminates swap operation. See how it works:

    

  public static final String reverseWithXOR(String string) {

        char[] array = string.toCharArray();

        int length = array.length;

        int half = (int) Math.floor(array.length / 2);

        for (int i = 0; i < half; i++) {

            array[i] ^= array[length - i - 1];

            array[length - i - 1] ^= array[i];

            array[i] ^= array[length - i - 1];

        }

        return String.valueOf(array);

    }

The performance of this method is very similar as the one implemented in the Java Library:

public static final String reverseWithStringBuilderBuiltinMethod(String string) {
        StringBuilder builder = new StringBuilder(string);
        return builder.reverse().toString();
    }

Reversing a string with StringBuilder built-in reverse method.

before=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz after=zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

Computed in 26000 ns

Reversing a string with swaps.

before=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz after=zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

Computed in 75000 ns

Reversing a string with XOR.

before=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz after=zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

Computed in 20000 ns

The source code for this article is part of the library: Java Algorithms - Implementation.