我正在尝试制作一个RecyclerView,以便选择多个项目。我正在为此使用androidx.recyclerview.selection.SelectionTracker
库。
我包含RecyclerView的片段也有一个TextView。当您单击TextView时,软键盘出现在屏幕上,我的应用程序崩溃了。
如果RecyclerView为空或其中只有足够的项目以使键盘与列表项不重叠,则该应用程序不会崩溃。
我绝对迷路了。任何见识将不胜感激。
这是Logcat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
}
}
答案 0 :(得分:0)
我想出了答案。
我实现了ItemKeyProvider
。
class MyItemKeyProvider(private val recyclerView: RecyclerView) :
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
}
}
然后创建了一个函数来创建跟踪器,并将该跟踪器分配给我在onCreateView
中调用的适配器。
private fun setUpTracker(
recyclerView: RecyclerView,
adapter: AddRoutineExerciseAdapter
) {
tracker = SelectionTracker.Builder(
"mySelection",
recyclerView,
MyItemKeyProvider(recyclerView),
ExerciseDetailsLookup(recyclerView),
StorageStrategy.createLongStorage()
).withSelectionPredicate(
SelectionPredicates.createSelectAnything()
).build()
adapter.tracker = tracker
}