Cannot set non-nullable LiveData value to null

Question

The error from the title is returned for the following code, which makes no sense

private val _error = MutableLiveData<String?>()
val error: LiveData<String?> get() = _error


_error.postValue(null)  //Error Cannot set non-nullable LiveData value to null [NullSafeMutableLiveData]

parameter String of _error is obviously nullable, am I doing something wrong?

Is this a compile time error ? What version of arch component you are using ? — ADM, Dec 16 '20 at 12:11
Try to invalidate the cache or update the dependencies, there is no problem with your code. — Vincent Sit, Dec 16 '20 at 12:13
@ADM yes compile time Lint error for release build only, debug build works fine. Android Studio also shows this error. Version is different for some components, lyfecycle-livedata is 2.3.0.beta01 — pedja, Dec 16 '20 at 12:19
@VincentSit everything is up to date, invalidate cache doesnt help — pedja, Dec 16 '20 at 12:19
Not sure if its the same but they have fixed an issue in recent release `2.3.0-alpha07` . [See this](https://developer.android.com/jetpack/androidx/releases/lifecycle#2.3.0-alpha07) . Just an advise its better to use Stable version of libraries in production. for a solution now you can ignore lint check — ADM, Dec 16 '20 at 12:44

score 46 · Accepted Answer · answered Jan 05 '21 at 05:37

This appears to be related to a bug already reported against androidx.lifecycle pre-release of 2.3.0 https://issuetracker.google.com/issues/169249668.

Workarounds I have found:

turn off or reduce severity of NullSafeMutableLiveData in

build.gradle

android {
  ...
  lintOptions {
    disable 'NullSafeMutableLiveData'
  }
}

or lint.xml in root dir

<?xml version="1.0" encoding="UTF-8"?>
<lint>
    <issue id="NullSafeMutableLiveData" severity="warning" />
</lint>

Do the work for MutableLiveData encapsulation via backing properties dance (which really hurts my eyes).

class ExampleViewModel : ViewModel() {

    private val _data1 = MutableLiveData<Int>()
    val data1: LiveData<Int> = _data1

    private val _data2 = MutableLiveData<Int?>()
    val data2: LiveData<Int?> = _data2

    fun funct() {
        _data1.value = 1
        _data2.value = null
    }
}

It hurts my eyes too, consider upvoting this https://youtrack.jetbrains.com/issue/KT-14663 — Aidanvii, Feb 07 '21 at 08:07

score 2 · Answer 2 · answered Mar 29 '21 at 20:19

2

This has been fixed in version 2.3.1.

https://developer.android.com/jetpack/androidx/releases/lifecycle#version_231_2

answered Mar 29 '21 at 20:19

DanielO

145
1
12

3

Nope, it's going to be fixed in v2.4.0 instead: https://issuetracker.google.com/issues/169249668#comment8 – anticafe Apr 27 '21 at 09:17
3

2.4.0 is out, and the issue is still there. – Ricardo Yubal Feb 06 '22 at 00:21

score 0 · Answer 3 · answered May 12 '21 at 07:21

0

It seems fixed in lifecycle 2.4.0-SNAPSHOT. Please wait for the official release.

answered May 12 '21 at 07:21

changhao cui

469
4
7

score 0 · Answer 4 · answered Nov 17 '21 at 06:22

0

This issue was coming in 2.3.0 also but after upgrading to 2.4.0 it is not coming.

answered Nov 17 '21 at 06:22

Sonu Sourav

2,926
2
12
25

score 0 · Answer 5 · answered Oct 10 '22 at 06:02

0

Add NullSafeMutableLiveData in your function,

@Suppress("NullSafeMutableLiveData")
fun clearBeforeData(){
    _articles.postValue(null)
}

answered Oct 10 '22 at 06:02

Md Tariqul Islam

2,736
1
20
35

Kwesi Welbred · Answer 6 · 2022-12-04T07:28:41.883

0

I think this has been fixed in version 2.4.1

this is my working solution

private val _roomDataObserver: MutableLiveData<List<Resource<ModelClass?>>?> = MutableLiveData()
val roomDataObserver: LiveData<List<Resource<ModelClass?>>?>
    get() = _classroomDataObserver

 override fun onCleared() {
    super.onCleared()
    Log.d("VIEWMODEL", "CLEARED")
    _roomDataObserver.value = null
}

edited Dec 04 '22 at 07:28

answered Dec 04 '22 at 07:18

Kwesi Welbred

69
1
5

Cannot set non-nullable LiveData value to null

6 Answers6