java - 更新 RecyclerView onChildChanged Firebase

Question

我正在尝试更新我的回收 View ，但出现错误

java.lang.ArrayIndexOutOfBoundsException: length=12; index=-1

mDatabase.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                Upload upload = dataSnapshot.getValue(Upload.class);
                uploads.add(upload);
                adapter = new MyAdapter(MainActivity.this, uploads);
                recyclerView.setAdapter(adapter);
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {

          //      uploads.clear();
                String key=dataSnapshot.getKey();
                Upload upload = dataSnapshot.getValue(Upload.class);
                uploads.set(uploads.indexOf(key),upload);
                adapter.notifyDataSetChanged();


            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

帮我解释一下这个逻辑。如果我在 onChildChanged 中除了 Notify 之外没有做任何事情，那么它将创建重复的 child

Answer 1

好的，我明白了

您将需要两个数组来执行此操作。

// Lists
private final List<ChatModel> lIndividualChats = new ArrayList<>();
private ArrayList<String> mKeys = new ArrayList<>();

然后

public void onChildAdded(@NonNull DataSnapshot dataSnapshot,
                        @Nullable String s) {

   ChatModel chatModel = dataSnapshot.getValue(ChatModel.class);
   lIndividualChats.add(chatModel);
   chatsAdapter.notifyDataSetChanged();

   String key = dataSnapshot.getKey();
   mKeys.add(key);

}

@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot,
                          @Nullable String s) {

   ChatModel chatModel = dataSnapshot.getValue(ChatModel.class);
   String key = dataSnapshot.getKey();

   int index = mKeys.indexOf(key);
   lIndividualChats.set(index,
                        chatModel);
   chatsAdapter.notifyDataSetChanged();

}

通过使用另一个简单字符串类型的数组，您将能够访问模型数组列表的索引。