question: public static boolean isAllUpperCase ( String str ) { if ( str == null ) return false ; boolean hasLetters = false ; char c ; for ( int i = str . length ( ) - 1 ; i >= 0 ; i -- ) { c = str . charAt ( i ) ; if ( Character . isLetter ( c ) ) { if ( ! Character . isUpperCase ( c ) ) return false ; hasLetters = true ; } } return hasLetters ; }
target:  returns true if the input string has letters and they are all UPPERCASE