question: private boolean isNumericString ( final String s ) { int i = 0 ; if ( s . length ( ) == 0 ) { return false ; } final char [ ] chars = s . toCharArray ( ) ; boolean seenDot = false ; if ( chars [ 0 ] == '+' || chars [ 0 ] == '-' ) { i ++ ; } while ( i < s . length ( ) ) { if ( chars [ i ] == '.' ) { if ( seenDot ) { return false ; } seenDot = true ; } else if ( chars [ i ] < '0' || chars [ i ] > '9' ) { return false ; } i ++ ; } return true ; }
target:  Check whether the string is a decimal numeric string.