Kotlin Operator

Operator Overloding

//example 1
operator fun Int.plus(b: Int) = this + b

//example 2
operator fun Int.plus(b: Any): String {
    return "$this $b"
}

println(10 + "ABC") // 10 ABC

//example 3
data class Position(val a: Int, val b: Int) {

    operator fun plus(item: Position): Position {
        return Position(a + item.a, b + item.b)
    }
}

val positionOne = Position(1, 2)
val positionTwo = Position(3, 4)
println(positionOne + positionTwo) // Position(a=4, b=6)

//example 4
data class Position(var a: Int, var b: Int) {
    operator fun unaryMinus(): Position {
        return Position(-a, -b)
    }
}

println(-Position(1, 2)) // Position(a=-1, b=-2)
println(-Position(-20, -10)) // Position(a=20, b=10)

example 5
data class Position(var a: Int, var b: Int) {

    operator fun inc(): Position {
        return Position(a.inc(), b.inc())
    }
}

var position1 = Position(1, 2)
var position2 = Position(8, 9)
println(position++) // Position(a=1, b=2)
println(++position) // Position(a=9 b=10)

 

Operator

operations	Expression	Transrated to	ex)
Unary	+a	a.unaryPlus()	왜 있는지 잘 모르겠다.
	-a	a.unaryMinus()	var a = 1 var b = -1 println(-a) // -1 println(-b) //  1
	!a	a.not()
Increments	a++	a.inc() + see below
decrements	a--	a.dec() + see below
Arithmetic	a + b	a.plus(b)
	a - b	a.minus(b)
	a * b	a.times(b)
	a / b	a.div(b)
	a % b	a.rem(b)
	a .. b	a.rangeTo(b)
in	a in b	b.contains(a)
	a !in b	!b.contains(a)
Indexed access	a[i]	a.get(i)
	a[i, j]	a.get(i, j)
	a[i_1, ..., i_n]	a.get(i_1, ..., i_n)
	a[i] = b	a.set(i, b)
	a[i, j] = b	a.set(i, j, b)
	a[i_1, ..., i_n] = b	a.set(i_1, ..., i_n, b)
invoke	a()	a.invoke()
	a(i)	a.invoke(i)
	a(i, j)	a.invoke(i, j)
	a(i_1, ..., i_n)	a.invoke(i_1, ..., i_n)
Augmented assignments	a += b	a.plusAssign(b)
	a -= b	a.minusAssign(b)
	a *= b	a.timesAssign(b)
	a /= b	a.divAssign(b)
	a %= b	a.remAssign(b)
Equality and inequality	a == b	a?.equals(b) ?: (b === null)
	a != b	!(a?.equals(b) ?: (b === null))
Comparison	a > b	a.compareTo(b) > 0
	a < b	a.compareTo(b) < 0
	a >= b	a.compareTo(b) >= 0
	a <= b	a.compareTo(b) <= 0