jodd-core/src/main/java/jodd/util/NaturalOrderComparator.java
private static char charAt(final String string, final int ndx) {
		if (ndx >= string.length()) {
			return 0;
		}
		return string.charAt(ndx);
	}
private static char charAt(final String string, final int ndx) {
		if (ndx >= string.length()) {
			return 0;
		}
		return string.charAt(ndx);
	}
Safe {@code charAt} that returns 0 when ndx is out of boundaries.