UNRESOLVED_REFERENCE未解析的参考:isInitialized [英] UNRESOLVED_REFERENCE Unresolved reference: isInitialized

问题描述

我正在尝试使用Kotlin的检查Lateinit属性状态的新功能，但出现此编译时错误Unresolved reference: isInitialized

I'm trying to use Kotlin's new feature of checking lateinit property status, but got this compile time error Unresolved reference: isInitialized

我已经用kotlin版本的kotlin_version = '1.2.0-beta-31' 配置了build.gradle文件(android studio版本是3.0) 并更新了相同版本的kotlin插件. 这是我的代码段，我在其中使用isInitialized检查.

I have configure my build.gradle file with kotlin version of kotlin_version = '1.2.0-beta-31' (android studio version is 3.0) and also updated kotlin plugin with same version. this is my code snippet, where I'm using isInitialized check.

还包含一个反射库

compile group: 'org.jetbrains.kotlin', name: 'kotlin-reflect', version: '1.2.0-beta-31'

.

lateinit var k: SomeObjectType
fun instance(): SomeObjectType {
    if (::k.isInitialized) {
        k = SomeObjectType()
    }
    return k
}

推荐答案

这是报告的错误，此处，并发布在 v1.2-rc-1

This is a bug as reported here and is released in v1.2-rc-1

更新:Kotlin 1.2 RC似乎可以使用"1.2.0-rc-39"，因此，如果您更新插件并使用此版本，则应解决此问题.

Update: Kotlin 1.2 RC appears to be available as '1.2.0-rc-39', so if you update your plugin and use this version, your issue should be resolved.

作为解决方法，直到安装rc-1，如在此项目中所示，在变量前加上this::即可.

As a workaround until you install rc-1, prefixing the variable with this:: works as can be shown in this project.

package com.example.john.so2

import android.support.v7.app.AppCompatActivity
import android.os.Bundle

data class SomeObjectType(val value: String)
lateinit var k: SomeObjectType

class MainActivity : AppCompatActivity() {

    lateinit var k: SomeObjectType

    fun instance(): SomeObjectType {

        if (this::k.isInitialized) {
            return k
        } else {
            return SomeObjectType("k was not initialized")
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        println("instance = ${instance()}")
        k = SomeObjectType("k was initialized")
        println("instance = ${instance()}")
    }


}

产生:

11-03 19:31:14.496 31982-31982/com.example.john.so2 I/System.out: instance = SomeObjectType(value=k was not initialized)
11-03 19:31:14.496 31982-31982/com.example.john.so2 I/System.out: instance = SomeObjectType(value=k was initialized)

顺便说一句，我留下了我原来的答案，因为它突出了正确的语法在"try-online"中有效的事实

BTW, I left my original answer as it highlights the fact that the correct syntax works in "try-online"

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