public static boolean isNumeric(String in) {
		char c = 0;
		for (int i = in.length(); i > 0; i--) {
			c = in.charAt(i - 1);
			if (!Character.isDigit(c)) {
				return false;
			}
		}
		return true;
	}
public static boolean isNumeric ( String in ) { char c = 0 ; for ( int i = in . length ( ) ; i > 0 ; i -- ) { c = in . charAt ( i - 1 ) ; if ( ! Character . isDigit ( c ) ) { return false ; } } return true ; }
tells whether all characters in a String are digits

@param in String to evaluate