In this tutorial you will learn about the Kotlin Operator Overloading and its application with practical example.
Kotlin Operator Overloading
Kotlin allows us to provide implementation for predefined set of operators on our types. These operators have fixed procedure and fixed symbolic representation, like + or *. When you will use operator in kotlin so it’s corresponding member function is called.
Let’s see some operations.
Unary Operations:
| Expression | Translated to |
| +a | a.unaryPlus() |
| -a | a.unaryMinus() |
| !a | a.not() |
Increment and Decrement Operations:
| Expression | Translated to |
| a++ | a.inc() |
| a– | a.dec() |
Binary Operations:
| Expression | Translated to |
| 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.mod(b) (deprecated) |
| a..b | a.rangeTo(b) |
Example: Overloading + Operator: See below example which is using for plus operator.
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fun main(args: Array<String>) { val point1 = OpOverloadingDemo(5, -7) val point2 = OpOverloadingDemo(6, 8) var sum = OpOverloadingDemo() sum = point1 + point2 println("W3Adda : The Sum is = (${sum.x}, ${sum.y})") } class OpOverloadingDemo(val x: Int = 0, val y: Int = 10) { // overloading plus function operator fun plus(p: OpOverloadingDemo) : OpOverloadingDemo { return OpOverloadingDemo(x + p.x, y + p.y) } } |
Output: The output of this code will be like below image.
In above example you can see that plus() is declared with operator keyword which will tell to complier that + operator will be overloaded. According to Above tables Expression point1+point2 will translated to point1.plus(point2).
Example: –Operator Overloading: –operator means decrement under the hood. In this example we will explain overloading of — operator. According to table suppose The expression is –a so it will translated to a.dec() for compiler and will tell that this operator is overloading.
Below line
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operator fun dec() = OpOverloadingDemo(--x, --y) |
is equivalent to
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operator fun dec(): OpOverloadingDemo { return OpOverloadingDemo(--x, --y) } |
See below code.
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fun main(args: Array<String>) { var p1 = OpOverloadingDemo(8, -12) --p1 println("W3Adda : The Result is = (${p1.x}, ${p1.y})") } class OpOverloadingDemo(var x: Int = 0, var y: Int = 10) { operator fun dec() = OpOverloadingDemo(--x, --y) } |
Output: The output of above code will be.
