nullpointerexception - Kotlin NullPointerException 发生

Question

我是新来的 kotlin , 当我开始 Null Safety 时，我对下面的情况感到困惑.

There's some data inconsistency with regard to initialization (an uninitialized this available in a constructor is used somewhere).

谁能更详细地描述一下情况？

Answer 1

示例改编自 Kotlin discussion on exactly this :

class Foo {
    val c: String          // Non-nullable

    init {
        bar()
        c = ""             // Initialised for the first time here
    }

    fun bar() {
        println(c.length)  // Oh dear
    }
}

fun main(args: Array<String>) {
    Foo()
}