Kotlin by Example: Variables

In Kotlin, variables are explicitly declared and used by the compiler to check type-correctness.	fun main() {
A variable can be declared with the `var` keyword.	var a: Int = 10
The type can be omitted from the declaration; it will be inferred by the compiler.	var b = a b++
A read-only reference (as opposed to a reassignable reference) can be declared with the `val` keyword. A read-only reference can not be reassigned; doing `c++` after the initialization would result in a compiler error, since it is a shorthand for `c = c + 1`.	val c = b + 1
Note that read-only references can still be mutable, it's only reassignment that is forbidden.	val myList = mutableListOf(10, 11) myList.add(12) println(myList)
Initialization can be done separately from the declaration, as long as the type is specified and the compiler can detected that the variable will always be initialized.	val d: String if (a + b + c < 100) { d = "the sum of a, b, and c is less than 100" } else { d = "the sum of a, b, and c is 100 or more" } println(d) }

$ kotlinc main.kt -include-runtime -d main.jar

$ java -jar Main.jar

[10, 11, 12]

the sum of a, b, and c is less than 100