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为什么回收器视图在片段中有NullPointerException?

android-recyclerview android-fragments kotlin android

Tommy - · 技术社区 · 4 年前

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)
    }
}

但不知何故,出现了以下错误:

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)

如何解决此问题?谢谢