StringUtils (Java)

gistfile1.java

import static java.lang.Math.pow;
public class JavaStringUtils {

    /**
     * 
     * @param source
     * @param c
     * @param interval
     * @return a new string with char c appended after each interval of characters
     */
    public static String interleave(String source, char c, int interval) {
        return
             source.length() < interval + 1
             ? source
             : source.substring(0, interval).concat(String.valueOf(c))
                     .concat(interleave(source.substring(interval), c, interval));
    }

    /**
     * 
     * @param source
     * @return a Double representation of a binary string
     */
    public static Double binaryString2Double(String source) {
        Double result = 0D;
        int length = source.length();
        for (int index = length - 1; index > -1; index--) {
            int numAtIndex = Integer.valueOf(String.valueOf(source.charAt(index)));
            result = result + numAtIndex * pow(2, index);
        }
        return result;
    }

}