Cannot create an instance of class ViewModel

Question

I am trying to write a sample app using Android architecture components and but even after trying for days I could not get it to work. It gives me the above exception.

Answer 1

If constructor of your viewmodel is public and accepts only application then make sure you can create your own model without ViewModelProvider. Error message might be much more clear:

val model = YouViewModel(app)

Answer 2

Make sure your ViewModel has constructor with only one parameter i.e. Application.

example:

public YourViewModel(Application application) {
    super(application);
    ...

Answer 3

Make the class and constructor public it solved my problem .

Answer 4

If you are using Kotlin make sure to replace any annotationProcessor in build.gradle with kapt.

Like:

annotationProcessor "android.arch.persistence.room:compiler:$rootProject.roomVersion"

Will become

kapt "android.arch.persistence.room:compiler:$rootProject.roomVersion"

and add

apply plugin: 'kotlin-kapt' on top of the buidl.gradle file.

Annotation Processing with Kotlin

Answer 5

1. Mostly, Solution is making Class and Constructor Public as the other answers
2. It may also be a runtime error, check the Logcat Error Logs if there are multiple causes listed.

Answer 6

if your PostViewModel class is an inner class, make sure its public and static