public double getExactMass(Integer atomicNumber, Integer massNumber) {
        if (atomicNumber == null || massNumber == null)
            return 0;
        for (IIsotope isotope : this.isotopes[atomicNumber]) {
            if (isotope.getMassNumber().equals(massNumber))
                return isotope.getExactMass();
        }
        return 0;
    }
public double getExactMass ( Integer atomicNumber , Integer massNumber ) { if ( atomicNumber == null || massNumber == null ) return 0 ; for ( IIsotope isotope : this . isotopes [ atomicNumber ] ) { if ( isotope . getMassNumber ( ) . equals ( massNumber ) ) return isotope . getExactMass ( ) ; } return 0 ; }
Get the exact mass of a specified isotope for an atom.
@param atomicNumber atomic number
@param massNumber the mass number
@return the exact mass