Simple yet effective XOR encryption

XORCrypt.gradle

private static int[] encrypt(String str, String key) {
    int[] output = new int[str.length()];
    for(int i = 0; i < str.length(); i++) {
        int o = ((int) str.charAt(i) ^ (int) key.charAt(i % (key.length() - 1))) + (char)('0');
        output[i] = o;
    }
    return output;
}

XORCrypt.java

/**
 * @author Prem Nirmal
 */
public class XORCrypt {
    static String value = "SampleStringToBeEncrypted";
    static String keyval = "thisIsAKey";

    public static void main(String args[]) { // test                
        int[] encrypted = encrypt(value,keyval);
        for (int anEncrypted : encrypted) System.out.printf("%d,", anEncrypted);
        System.out.println("");
        System.out.println(decrypt(encrypted,keyval));
    }

    private static int[] encrypt(String str, String key) {
        int[] output = new int[str.length()];
        for(int i = 0; i < str.length(); i++) {
            int o = ((int) str.charAt(i) ^ (int) key.charAt(i % (key.length() - 1))) + '0';
            output[i] = o;
        }
        return output;
    }

    private static int[] string2Arr(String str) {
        String[] sarr = str.split(",");
        int[] out = new int[sarr.length];
        for (int i = 0; i < out.length; i++) {
            out[i] = Integer.valueOf(sarr[i]);
        }
        return out;
    }

    private static String decrypt(int[] input, String key) {
        StringBuilder output = new StringBuilder();
        for(int i = 0; i < input.length; i++) {
            output.append((char) ((input[i] - 48) ^ (int) key.charAt(i % (key.length() - 1))));
        }
        return output.toString();
    }
}

XORCrypt.kt

package app.cind.android.service.payment

/**
 * @author Prem Nirmal
 */
object XORCrypt {
    private var value = "SampleStringToBeEncrypted"
    private var keyval = "thisIsAKey"

    @JvmStatic
    fun main() { // test                
        val encrypted = encrypt(value, keyval)
        for (anEncrypted in encrypted) System.out.printf("%d,", anEncrypted)
        println("")
        println(decrypt(encrypted, keyval))
    }

    private fun encrypt(str: String, key: String): IntArray {
        val output = IntArray(str.length)
        for (i in 0 until str.length) {
            val o = (str[i].toInt() xor key[i % (key.length - 1)].toInt()) + '0'.toInt()
            output[i] = o
        }
        return output
    }

    private fun string2Arr(str: String): IntArray {
        val sarr = str.split(",".toRegex()).dropLastWhile { it.isEmpty() }.toTypedArray()
        val out = IntArray(sarr.size)
        for (i in out.indices) {
            out[i] = Integer.valueOf(sarr[i])
        }
        return out
    }

    private fun decrypt(input: IntArray, key: String): String {
        val output = StringBuilder()
        for (i in input.indices) {
            output.append((input[i] - 48 xor key[i % (key.length - 1)].toInt()).toChar())
        }
        return output.toString()
    }
}