java.lang.IllegalStateException: pb must not be null at TopHeadlinesFragment?

Question

I am developing news app and I have implemented livedata with progress bar but I am getting following exception in my code

java.lang.IllegalStateException: pb must not be null
 at yodgorbek.komilov.musobaqayangiliklari.ui.TopHeadlinesFragment$initViewModel$2.onChanged(TopHeadlinesFragment.kt:60)
 at yodgorbek.komilov.musobaqayangiliklari.ui.TopHeadlinesFragment$initViewModel$2.onChanged(TopHeadlinesFragment.kt:22)
 at androidx.lifecycle.LiveData.considerNotify(LiveData.java:131)
 at androidx.lifecycle.LiveData.dispatchingValue(LiveData.java:144)
 at androidx.lifecycle.LiveData$ObserverWrapper.activeStateChanged(LiveData.java:442)
 at androidx.lifecycle.LiveData$LifecycleBoundObserver.onStateChanged(LiveData.java:394)
 at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
 at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300)
 at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339)
 at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145)
 at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131)
 at androidx.fragment.app.Fragment.performStart(Fragment.java:2637)
 at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:915)
 at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
 at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
 at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439)
 at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079)
 at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869)
 at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
 at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
 at androidx.fragment.app.FragmentManagerImpl$2.run(FragmentManagerImpl.java:150)
 at android.os.Handler.handleCallback(Handler.java:873)
 at android.os.Handler.dispatchMessage(Handler.java:99)
 at android.os.Looper.loop(Looper.java:201)
 at android.app.ActivityThread.main(ActivityThread.java:6820)
 at java.lang.reflect.Method.invoke(Native Method)
 at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:922)

below my TopHeadlinesFragment.kt class

class TopHeadlinesFragment : Fragment() {

    private  var binding: FragmentTopHeadlinesBinding? = null
    private val viewModel by viewModel<MainViewModel>()
    private lateinit var topHeadlinesAdapter: TopHeadlinesAdapter
    // private   val newsRepository: NewsRepository by inject()
    private  var article:List<Article>? = null


    //3
    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view = inflater.inflate(
            R.layout.fragment_top_headlines
            , container, false
        )
        val recyclerView = view.findViewById(R.id.recyclerView) as RecyclerView
        val pb = view.findViewById(R.id.pb) as ProgressBar
        topHeadlinesAdapter = TopHeadlinesAdapter(recyclerView.context, article)
        recyclerView.layoutManager = LinearLayoutManager(context)
        recyclerView.adapter = topHeadlinesAdapter
        initViewModel()

        binding?.lifecycleOwner
        return binding?.root


    }

    private fun initViewModel() {
        viewModel?.sportList?.observe(this, Observer { newList ->
            topHeadlinesAdapter.updateData(newList)
        })

        viewModel?.showLoading?.observe(this, Observer { showLoading ->
            pb.visibility = if (showLoading) View.VISIBLE else View.GONE
        })

        viewModel?.showError?.observe(this, Observer { showError ->
            (showError)
        })

        viewModel?.loadNews()
    }
}

below fragment_top_headlines.xml

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ProgressBar
        android:id="@+id/pb"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

I have followed all stackoverflow suggestion it did not solve my problem. what I want to know where exactly I am making mistake what I have to in order avoid an exception.

what I have tried

1.Invalidate cache restart 2.clean and rebuild project 3.I have checked that progress bar initialized already. 4.I tried this stackoverflow link as well Android: Progressbar must not be null using Kotlin 5. I have tried progress bar declared as global variable it did not work

below my MainViewModel.kt

@Suppress("UNCHECKED_CAST")
class MainViewModel(val newsRepository: NewsRepository) : ViewModel(), CoroutineScope {
    // Coroutine's background job
    val job = Job()
    // Define default thread for Coroutine as Main and add job
    override val coroutineContext: CoroutineContext = Dispatchers.Main + job

    val showLoading = MutableLiveData<Boolean>()
    val sportList = MutableLiveData<List<Article>>()
    val showError = SingleLiveEvent<String>()

    fun loadNews() {
        // Show progressBar during the operation on the MAIN (default) thread
        showLoading.value = true
        // launch the Coroutine
        launch {
            // Switching from MAIN to IO thread for API operation
            // Update our data list with the new one from API
            val result = withContext(Dispatchers.IO) {
                newsRepository?.getNewsList()
            }
            // Hide progressBar once the operation is done on the MAIN (default) thread
            showLoading.value = false
            when (result) {

                is UseCaseResult.Success<*> -> {
                    sportList.value = result.data as List<Article>
                }
                is Error -> showError.value = result.message
            }
        }
    }

    override fun onCleared() {
        super.onCleared()
        // Clear our job when the linked activity is destroyed to avoid memory leaks
        job.cancel()
    }
}

I have tried below provided answers as well it did not solve the issue

Not sure but just thinking if val pb is not global and only available in the method onCreateView try making it global and check if it works — Manoj Mohanty, Mar 18 '20 at 19:34
what is your suggestion it is still appearing I have declared as global but it is still app crashing giving above exception — Edgar, Mar 18 '20 at 19:40
Are you using dataBinding? the other way would be just comment the code which throws the error and validate if your recyclerview is updated post data load — Manoj Mohanty, Mar 18 '20 at 19:51
next would be to put a debugger at exact location and validate why is null — Manoj Mohanty, Mar 18 '20 at 19:52
yes I am using databinding but i am still new for data binding thats why what is your suggestion can explain with coding sample — Edgar, Mar 18 '20 at 19:52
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/209874/discussion-between-sashabeliy-and-manoj-mohanty). — Edgar, Mar 18 '20 at 19:54

score 0 · Answer 1 · answered Mar 18 '20 at 15:51

0

you had not initialized your binding:

 private  var binding: FragmentTopHeadlinesBinding? = null

it is still null

answered Mar 18 '20 at 15:51

Nurseyit Tursunkulov

8,012
12
44
78

I think it is not case – Edgar Mar 18 '20 at 17:15
it is this case, otherwise, where are you initializing it? – Nurseyit Tursunkulov Mar 19 '20 at 12:09

score 0 · Answer 2 · answered Mar 18 '20 at 16:00

0

    viewModel?.sportList?.observe(this, Observer { newList ->
        topHeadlinesAdapter.updateData(newList)
    })

    viewModel?.showLoading?.observe(this, Observer { showLoading ->
        pb.visibility = if (showLoading) View.VISIBLE else View.GONE
    })

    viewModel?.showError?.observe(this, Observer { showError ->
        (showError)
    })

Should be

    viewModel.sportList.observe(viewLifecycleOwner) { newList ->
        topHeadlinesAdapter.updateData(newList)
    }

    viewModel.showLoading.observe(viewLifecycleOwner) { showLoading ->
        pb.visibility = if (showLoading) View.VISIBLE else View.GONE
    }

    viewModel.showError.observe(viewLifecycleOwner) { showError ->
        (showError)
    }

You might want to make viewModel into lateinit var.

answered Mar 18 '20 at 16:00

EpicPandaForce

79,669
27
256
428

Well, fix the errors then. For example, add `lifecycle-ktx`, and import the extension function that lets you ditch typing out `Observer {` all the time. – EpicPandaForce Mar 18 '20 at 16:41
thank you for your answer but you code not working better use my old code – Edgar Mar 18 '20 at 16:47
1

You should be using `viewLifecycleOwner`, but you do you ¯\\_(ツ)_/¯ – EpicPandaForce Mar 18 '20 at 16:48
can you see my MainViewModel.kt I want to know where exactly I am making mistake in Fragment and My FragmentTopHeadlinesBinding not implement correctly right? – Edgar Mar 18 '20 at 17:06
what do you think main problem – Edgar Mar 18 '20 at 19:21

java.lang.IllegalStateException: pb must not be null at TopHeadlinesFragment?

2 Answers2