public static boolean startWith(String source, String target){
		if (source == null || target == null) {
			throw new IllegalArgumentException();
		}
    	char[] sourceCharArray = source.toCharArray();
    	char[] targetCharArray = target.toCharArray();
    	for (int i = 0, len = targetCharArray.length; i < len; i++) {
			if (sourceCharArray[i] != targetCharArray[i]) {
				return false;
			}
		}
    	return true;
    }