Kotlin isInitialized

0-lateinit-not-initialized.kt

class A {
    lateinit var s: String
    fun print() {
        println(s)
    }
}

fun main(args: Array<String>) {
    A().print()
}

1-lateinit-isInitialized.kt

class B {
    lateinit var s: String
    fun print() {
        if (::s.isInitialized) {
            println(s)
        }
    }
}

fun main(args: Array<String>) {
    B().print()
}

2-lateinit-unresolved-reference.kt

class C {
    lateinit var s: String
    fun print() {
        if (s.isInitialized) {  // この行でUnresolved referenceというコンパイルエラーが発生する
            println(s)
        }
    }
}

fun main(args: Array<String>) {
    C().print()
}

3-lateinit-only-be-called-on-a-lateinit-ref.kt

class D {
    var s: String  // コンパイルエラー: Property must be initialized
    fun print() {
        if (::s.isInitialized) {  // コンパイルエラー: This declaration can only be called on a reference to a lateinit property
	        println(s)
        }
    }
}

fun main(args: Array<String>) {
    D().print()
}

4-lateinit-duplicated-isInitialized.diff

-        if (::x.isInitialized) {
+        if (x.isInitialized) {

4-lateinit-duplicated-isInitialized.kt

class X(val isInitialized: Boolean) {}

class Z {
    lateinit var x: X
    fun print() {
        if (::x.isInitialized) {
            print("Initialized")
        } else {
            print("Not initialized")
        }
    }
}

fun main(args: Array<String>) {
    val z = Z()
    z.x = X(false)
    z.print()
}