在使用recyclerview分离Viewpager中的视图之前，如何分离父对象？

编程问答 2022-08-16

问题描述

由于recyclerview，我在内存泄漏方面遇到了麻烦，它说View detached and has parent在LeakCanary中。我尝试将recyclerview上的onDestroyView设置为null，但仍然没有任何反应。下面是我的片段和LeakCanary的堆栈跟踪：

public class CancelledOrdersFragment extends Fragment {
    private RecyclerView recyclerView;
    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CancelledOrdersAdapter adapter;
    private OrderTransactionsModel model;

    public CancelledOrdersFragment() {
    }


    @Override
    public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        View itemView = inflater.inflate(R.layout.fragment_cancelled_orders,container,false);
        recyclerView = itemView.findViewById(R.id.cancelled_orders_rv);

        linearlayoutmanager linearlayoutmanager1 = new linearlayoutmanager(itemView.getContext());
        linearlayoutmanager1.setorientation(linearlayoutmanager.VERTICAL);
        recyclerView.setLayoutManager(linearlayoutmanager1);

        Paper.init(itemView.getContext());
        String storeID = Paper.book().read("userid");

        Query query = db.collection("Transactions").whereEqualTo("storeID",storeID).whereEqualTo("transactionStatus","cancelled").orderBy("orderTimeout",Query.Direction.DESCENDING);

        PagedList.Config Bconfig = new PagedList.Config.Builder()
                .setEnablePlaceholders(false)
                .setPrefetchdistance(10)
                .setPageSize(8)
                .build();

        FirestorePagingOptions<OrderTransactionsModel> options = new FirestorePagingOptions.Builder<OrderTransactionsModel>()
                .setLifecycleOwner(getActivity())
                .setQuery(query,Bconfig,snapshot -> {
                    OrderTransactionsModel transactionsModel = snapshot.toObject(OrderTransactionsModel.class);
                    String transID = transactionsModel.getTransactionID();
                    String tranCOde = transactionsModel.getTransactionCode();
                    double storetotal = transactionsModel.getStoretotal();
                    HashMap<String,Object> CouponUsed = transactionsModel.getCouponUsed();
                    HashMap<String,Date> OrderStatus = transactionsModel.getorderStatus();

                    model = new OrderTransactionsModel(transID,storeID,storetotal,CouponUsed,OrderStatus,tranCOde);
                    return model;
                })
                .build();

        adapter = new CancelledOrdersAdapter(options);
        recyclerView.setAdapter(adapter);
        adapter.notifyDataSetChanged();

        return itemView;
    }


    @Override
    public void onDestroyView() {
        super.onDestroyView();
        adapter.stopListening();
        recyclerView = null;
    }

    @Override
    public void onViewStateRestored(@Nullable Bundle savedInstanceState) {
        super.onViewStateRestored(savedInstanceState);
        adapter.startListening();
    }

 ┬───
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │ GC Root: Local variable in native code
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ android.net.ConnectivityThread instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: NO (PathClassLoader↓ is not leaking)
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Thread name: 'ConnectivityThread'
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ ConnectivityThread.contextClassLoader
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ dalvik.system.PathClassLoader instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: NO (InternalLeakCanary↓ is not leaking and A ClassLoader is never leaking)
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ PathClassLoader.runtimeInternalObjects
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ java.lang.Object[] array
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: NO (InternalLeakCanary↓ is not leaking)
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ Object[].[1614]
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ leakcanary.internal.InternalLeakCanary class
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: NO (OrdersActivity↓ is not leaking and a class is never leaking)
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ static InternalLeakCanary.resumedActivity
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ com.dreamakers.clustore.clustorestore.Activity.OrdersActivity instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: NO (Activity#mDestroyed is false)
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ OrdersActivity.mLifecycleRegistry
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                     ~~~~~~~~~~~~~~~~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ androidx.lifecycle.LifecycleRegistry instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ LifecycleRegistry.mObserverMap
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                        ~~~~~~~~~~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ androidx.arch.core.internal.FastSafeIterableMap instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ FastSafeIterableMap.mEnd
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                          ~~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ androidx.arch.core.internal.SafeIterableMap$Entry instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ SafeIterableMap$Entry.mKey
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                            ~~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ com.dreamakers.clustore.clustorestore.Adapter.CancelledOrdersAdapter instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ CancelledOrdersAdapter.mObservable
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                             ~~~~~~~~~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ androidx.recyclerview.widget.RecyclerView$AdapterDataObservable instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ RecyclerView$AdapterDataObservable.mObservers
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                                         ~~~~~~~~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ java.util.ArrayList instance
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ ArrayList.elementData
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                ~~~~~~~~~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ java.lang.Object[] array
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ Object[].[0]
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │               ~~~
2020-08-19 16:23:59.404 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ androidx.recyclerview.widget.RecyclerView$RecyclerViewDataObserver instance
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: UNKNowN
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ RecyclerView$RecyclerViewDataObserver.this$0
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │                                            ~~~~~~
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ├─ androidx.recyclerview.widget.RecyclerView instance
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    Leaking: YES (View detached and has parent)
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    mContext instance of com.dreamakers.clustore.clustorestore.Activity.OrdersActivity with mDestroyed = false
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    View#mParent is set
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    View#mAttachInfo is null (view detached)
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    View.mID = R.id.cancelled_orders_rv
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    View.mWindowAttachCount = 1
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: │    ↓ RecyclerView.mParent
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ╰→ android.widget.FrameLayout instance
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     Leaking: YES (ObjectWatcher was watching this because com.dreamakers.clustore.clustorestore.Activity.CancelledOrdersFragment received Fragment#onDestroyView() callback (references to its views should be cleared to prevent leaks))
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     key = 1bb796b4-4c87-4320-b90a-a348a14e616e
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     watchDurationMillis = 8633
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     retainedDurationMillis = 3631
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     mContext instance of com.dreamakers.clustore.clustorestore.Activity.OrdersActivity with mDestroyed = false
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     View#mParent is null
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     View#mAttachInfo is null (view detached)
2020-08-19 16:23:59.405 11647-13298/com.dreamakers.clustore.clustorestore D/LeakCanary: ​     View.mWindowAttachCount = 1

解决方法

泄漏跟踪表明OrdersActivity仍然有效（没有被破坏，一切都很好），并且其生命周期注册表中有一个包含CancelledOrdersAdapter的mObserverMap。

根据代码，似乎CancelledOrdersAdapter和R.id.cancelled_orders_rv RecyclerView的生命周期应该保持一致。

但是，当拆开回收台视图时，CancelledOrdersAdapter将保留在内存中，因为它注册为活动生命周期的观察者（此时该活动并未被破坏）。该修复程序可能会将CancelledOrdersAdapter注册为片段视图生命周期的观察者，即Fragment.viewLifecycleOwner

androidandroidandroid-recyclerviewandroid-studioleakcanarymemory-leaks