CODEWITHSUNDEEP
androidkotlin
Jemo Mgebrishvili
Jemo Mgebrishvili

Reputation: 5497

UNRESOLVED_REFERENCE 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

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.

also had a reflect library included

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
}

Upvotes: 7

Views: 5288

Answers (5)

MarGin
MarGin

Reputation: 2558

isInitialized is not working for local lateinit var but it is working fine for global ones.

Upvotes: 1

harsh_v
harsh_v

Reputation: 3269

Project_level.gradle

buildscript {
    ext.kotlin_version = '1.2.30'

    ...
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    ...
    }
}

App_level.gradle

dependencies {
    ...
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
    ...
}

Usage

class Foo() {

    lateinit var theVariable: String

    // this is required to access isInitialized
    fun foo() {
        this::theVariable.isInitialized
    }
}

Upvotes: 0

Ivo Stoyanov
Ivo Stoyanov

Reputation: 18929

If isInitialized appears in red, check that you have upgraded your Kotlin version to >1.2

Check both in your Project and Module Gradle files:

  1. In your Project Gradle check the row:

    ext.kotlin_version = "1.2.21"

  2. In your Module Gradle check the row:

    compile 'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.2.21'

Despite the other comments, in my case it was NOT necessary to add the reflection library:

"org.jetbrains.kotlin:kotlin-reflect:$kotlinVersion"

Upvotes: 0

nPn
nPn

Reputation: 16758

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

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.

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()}")
    }


}

which yields:

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)

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

Upvotes: 5

nPn
nPn

Reputation: 16758

Is your code valid Kotlin code? I tried the following and it seemed to work as expected.

data class SomeObjectType(val value: String) 

lateinit var k: SomeObjectType

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

fun main(args: Array<String>) {
    println("inst = ${instance()}")
    k = SomeObjectType("was initialized")
    println("inst = ${instance()}")
}

producing :

inst = SomeObjectType(value=k was not initialized)
inst = SomeObjectType(value=was initialized)

When I tried what you have above: (with the added class SomeObjectType()

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

it complains about the instance = SomeObjectType() line and the return instance line, which I think makes sense to me. Line 5 being the instance = SomeObjectType() and line 7 being the return instance line.

Error:(5, 8) Function invocation 'instance()' expected
Error:(5, 8) Variable expected
Error:(7, 11) Function invocation 'instance()' expected

Here are the links to the online examples. working example, broken example

Upvotes: 0

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