Kotlin Runtime: Check, Require and Assert

Runtime checks

• require: check arguments. Throws an IllegalArgumentException if the value is false.
• check: check states. Throws an IllegalStateException if the value is false.
• assert: other usage like check results. Throws an AssertionError if the value is false and runtime assertions have been enabled on the JVM using the -ea JVM option.

require

Check arguments, throws an IllegalArgumentException if false.

fun save(age: Int) {    require(age >= 0) { "Age must be positive integer: $age" }    // save the data}

check

Check states, throws an IllegalStateException if false.

class Worker {    private var isRunning = false    fun run() {        check(isRunning == false) { "Working is already running" }    }}

assert

Check results, throws an AssertionError if false.

val name = getName()assert(name.isNullOrEmpty() == false) { "getName result is null or empty" }