当打开软键盘时,Android Recyclerview Java.lang.NullPointerException。

问题描述 投票:0回答:1

我想制作一个可以选择多个项目的RecyclerView。我正在使用 androidx.recyclerview.selection.SelectionTracker 库来实现。

我的包含RecyclerView的片段也有一个TextView。当你点击进入TextView时,软键盘就会出现在屏幕上,我的应用就会崩溃。

如果RecyclerView是空的,或者只有足够的项目在其中,键盘不会重叠列表项目,应用程序不会崩溃。

我完全迷茫了。任何见解都将是非常感激的。

以下是Logcat的错误输出。

2020-05-30 14:56:14.511 31037-31037/? E/exercisetracke: Unknown bits set in runtime_flags: 0x8000
2020-05-30 14:57:29.847 31037-31037/com.example.android.exercisetracker E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.android.exercisetracker, PID: 31037
    java.lang.NullPointerException: Attempt to invoke virtual method 'int androidx.recyclerview.widget.RecyclerView$ViewHolder.getAdapterPosition()' on a null object reference
        at androidx.recyclerview.selection.StableIdKeyProvider.onDetached(StableIdKeyProvider.java:90)
        at androidx.recyclerview.selection.StableIdKeyProvider$1.onChildViewDetachedFromWindow(StableIdKeyProvider.java:69)
        at androidx.recyclerview.widget.RecyclerView.dispatchChildDetached(RecyclerView.java:7546)
        at androidx.recyclerview.widget.RecyclerView.removeDetachedView(RecyclerView.java:4349)
        at androidx.recyclerview.widget.RecyclerView$LayoutManager.removeAndRecycleScrapInt(RecyclerView.java:9243)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep3(RecyclerView.java:4207)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3862)
        at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at androidx.appcompat.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:446)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at com.android.internal.policy.DecorView.onLayout(DecorView.java:779)
        at android.view.View.layout(View.java:21912)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3080)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2590)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1721)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7598)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:966)
        at android.view.Choreographer.doCallbacks(Choreographer.java:790)
        at android.view.Choreographer.doFrame(Choreographer.java:725)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:951)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

适配器

class AddRoutineExerciseAdapter internal constructor(context: Context) :
    RecyclerView.Adapter<AddRoutineExerciseAdapter.ViewHolder>() {

    init {
        setHasStableIds(true)
    }

    private val inflater: LayoutInflater = LayoutInflater.from(context)
    private var exercises: List<Exercise> = emptyList<Exercise>()
    var tracker: SelectionTracker<Long>? = null

    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val exerciseTitle: TextView = itemView.findViewById(R.id.exercise_title)
        //val exerciseArea: TextView = itemView.findViewById(R.id.exercise_area)

        fun getItemDetails(): ItemDetailsLookup.ItemDetails<Long> =
            object : ItemDetailsLookup.ItemDetails<Long>() {
                override fun getPosition(): Int = adapterPosition
                override fun getSelectionKey(): Long? = itemId
            }

        fun bind(value: Exercise, isActivated: Boolean = false) {
            exerciseTitle.text = value.toString()
            itemView.isActivated = isActivated
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val itemView = inflater.inflate(R.layout.exercise_list_item, parent, false)
        return ViewHolder(itemView)
    }

    override fun getItemCount(): Int {
        return exercises.size
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val current = exercises[position]
        holder.exerciseTitle.text = current.exerciseName
        // holder.exerciseArea.text = current.exerciseBodyType

        tracker?.let {
            holder.bind(
                current,
                it.isSelected(position.toLong())
            )
        }
    }

    override fun getItemId(position: Int): Long = position.toLong()

    fun setExercises(exercises: List<Exercise>) {
        this.exercises = exercises
        notifyDataSetChanged()
    }
}

片段

class AddRoutineFragment : Fragment() {
    private lateinit var exerciseViewModel: ExerciseViewModel
    var tracker: SelectionTracker<Long>? = null

    companion object {
        fun newInstance(): ExerciseFragment {
            return ExerciseFragment()
        }
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        val view = inflater.inflate(R.layout.fragment_add_routine, container, false)
        val activity = activity as Context

        val recyclerView: RecyclerView = view.findViewById(R.id.rv_add_routine_exercises)
        val adapter = AddRoutineExerciseAdapter(activity)

        recyclerView.layoutManager = LinearLayoutManager(activity)
        recyclerView.adapter = adapter
        exerciseViewModel = ViewModelProvider(this).get(ExerciseViewModel::class.java)
        exerciseViewModel.allExercises.observe(viewLifecycleOwner, Observer { exercises ->
            exercises?.let { adapter.setExercises(it) }
        })

        tracker = SelectionTracker.Builder<Long>(
            "mySelection",
            recyclerView,
            StableIdKeyProvider(recyclerView),
            ExerciseDetailsLookup(recyclerView),
            StorageStrategy.createLongStorage()
        ).withSelectionPredicate(
            SelectionPredicates.createSelectAnything()
        ).build()

        adapter.tracker = tracker

        return view
    }
}
android kotlin android-recyclerview
1个回答
0
投票

我想出了答案。

我实现了一个 ItemKeyProvider 这就解决了这个问题。

    ItemKeyProvider<Long>(ItemKeyProvider.SCOPE_MAPPED) {

    override fun getKey(position: Int): Long? {
        return recyclerView.adapter?.getItemId(position)
    }

    override fun getPosition(key: Long): Int {
        val viewHolder = recyclerView.findViewHolderForItemId(key)
        return viewHolder?.layoutPosition ?: RecyclerView.NO_POSITION
    }
}
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