[FIXED] Why is the recycler view has NullPointerException in fragment?

Issue

so here is the code for my recycler view adapter, which is located at onCreate:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    databaseReference = FirebaseDatabase.getInstance().getReference("profilUsaha")
    auth = FirebaseAuth.getInstance()
    uid = auth.currentUser?.uid.toString()

    daftar_pesan_recycler_view.adapter = adapter
    listenForLatestMessages()

    arguments?.let {
        param1 = it.getString(ARG_PARAM1)
        param2 = it.getString(ARG_PARAM2)
    }
}

But somehow, the following error appears:

2022-07-20 00:29:23.872 17032-17032/com.example.gesit E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.gesit, PID: 17032
java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
    at com.example.gesit.PesanFragment.onCreate(PesanFragment.kt:51)
    at androidx.fragment.app.Fragment.performCreate(Fragment.java:2981)
    at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:474)
    at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:257)
    at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1840)
    at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1758)
    at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1701)
    at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:488)
    at android.os.Handler.handleCallback(Handler.java:938)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loopOnce(Looper.java:226)
    at android.os.Looper.loop(Looper.java:313)
    at android.app.ActivityThread.main(ActivityThread.java:8669)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135)

How to fix this issue? Thanks.

Solution

onCreate() is too early in the fragment lifecycle, the fragment view has not yet been created.

You can move the view setup code such as setting recyclerview adapter to onViewCreated().

Answered By - laalto
Answer Checked By - David Marino (JavaFixing Volunteer)