Kotlin | IntelliJ IDEA

Parameter hints

Controls whether hints should appear for function and constructor arguments.

            data class User(val id: Int)

            fun printSum(a: Int, b: Int) = println(a + b)

            fun hintsDemo() {
                val u = User(0)     // calling constructor
                printSum(1, 1)      // calling function
            }
        

Use Exclude list to disable parameter inlay hints for specific methods.

Types

Property types	Controls whether hints should appear when assigning a value to a property whose type is not explicitly specified. class User(_id: Int = 0) { val id = _id // inferred property type }
Local variable types	Controls whether hints should show the type when a local variable, whose type is not specified, is assigned some value. The type is not shown for constants. fun returnHello(): String = "Hello" fun hintsDemo() { val s = returnHello() // "s" gets the String type }
Function return types	Controls whether hints should appear for functions with inferred return types. fun sum(i1: Int, i2: Int) = i1 + i2 // the return type (Int) is inferred
Function parameter types	Controls whether hints should appear for lambda parameters without a type. fun hintsDemo() { listOf(1, 2, 3).filter { elem -> // parameter with inferred type elem >= 3 } }

Lambdas

Return expressions	Controls whether hints should appear for multiline lambdas that return a value. This is useful in complex constructs, where it is easy to forget that a lambda is returning something. fun numbers(): String { val numbers = StringBuilder() return with(numbers) { // "with" structure starts here for (letter in '0'..'9') { append(letter) } toString() // used as the return value } }
Implicit receivers and parameters	Controls whether hints should appear for lambdas' implicit receivers. fun numbers(): String { val numbers = StringBuilder() return with(numbers) { // the implicit receiver is "numbers" (StringBuilder) for (letter in '0'..'9') { append(letter) } toString() } }

URL path inlay

Controls whether an inlay hint should appear at URL mappings allowing you to quickly access the related actions.