question: public static boolean isNumeric ( String str ) { if ( str == null || str . length ( ) == 0 ) { return false ; } int sz = str . length ( ) ; int start = 0 ; if ( sz > 0 && str . charAt ( 0 ) == '-' ) { if ( sz == 1 ) { return false ; } start = 1 ; } for ( int i = start ; i < sz ; i ++ ) { if ( Character . isDigit ( str . charAt ( i ) ) == false ) { return false ; } } return true ; }
target:  Check if the given string represents a number