[SOLVED] Creating the analogue of BigInteger.ZERO for own data type in Kotlin

Creating the analogue of BigInteger.ZERO for own data type in Kotlin

So, as is well-known, Kotlin is able to access Java libraries, and among them is the BigInteger class. And this class has a very handy feature: There is a keyword, called "BigInteger.ZERO", which returns a BigInteger object whose value equals zero.

Now I am writing a fraction data type, and I'd very much like to do the same thing for it. But the problem with just putting a val inside the class is that this first needs an object to begin with; it's not a "static" constant, so to say.

I'd be very grateful indeed for any forthcoming replies.

Solution

You can put the constant as a val inside the companion object of your class:

class Fraction {
    ...
    companion object {
        val ZERO = Fraction()
    }
}

Then you can call your constant by Fraction.ZERO.

Note that this only makes sense if your fraction class is immutable.