How to solve this fraction problem？

Question

public FractionInterface add(FractionInterface secondFraction)
{
// implement this method!
// a/b + c/d is (ad + cb)/(bd)
// invoke covert() and reduce() before return the result
Fraction newFraction = new Fraction(num,den);

secondFraction.num = newFraction.num*secondFraction.den + newFraction.den*secondFraction.num;
secondFraction.den = newFraction.den * secondFraction.den;
setFraction(secondFraction.num,secondFraction.den);
secondFraction.convert();
secondFraction.reduce();
return secondFraction;
} // end add

the first fraction is firstOperand = new Fraction(7, 8);
and the second fraction is (9,16); and should pass the class"public FractionInterface add"
like
Fraction nineSixteenths = new Fraction(9, 16);
double result = firstOperand.add(nineSixteenths);
after add, the result should be (7*16 + 9*8)/(8*16);
my problem is how to get the secondFration num and den`s value.
as my code, secondFraction.num is an error because num cannot be resolved or is not a field.
how to solve this isuue?
thanks

Answer 1

Fraction and FractionInterface appears to be a self-defined class and interface. Without the full code, it's a little hard to tell what getters and setters we can use, and what other methods are available to be utilized. Can you provide the full code, or at least the class definition of Fraction and FractionInterface?