调用 LiveData onChanged() 方法时，ListAdapter 项目呈现不正确。 DiffUtil areContentsTheSame() 可能存在问题？

Question

我目前正在创建一个 Android 应用程序来帮助您完成任务。我将 LiveData 与列出 Fragment 和 DiffUtil 中所有不同任务的 ListAdapter 一起使用，以测试 ListAdapter 中的更改。在我解释我的问题之前：这里有一些相关代码：

SubTaskFragment.java:

public class SubTaskFragment extends Fragment {
private RecyclerView recyclerView;

private SubTaskAdapter adapter;
private SubTaskViewModel viewModel;

private static final String TAG = "SubTaskFragment";

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment and setup recycler view
    View rootView = inflater.inflate(R.layout.fragment_sub_task, container, false);
    recyclerView = (RecyclerView) rootView.findViewById(R.id.sub_task_recycler_view);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

    //set adapter
    adapter = new SubTaskAdapter(getContext());
    recyclerView.setAdapter(adapter);

    viewModel = ViewModelProviders.of(this).get(SubTaskViewModel.class);
    viewModel.getSubTasks().observe(getViewLifecycleOwner(), new Observer<List<SubTask>>() {
        @Override
        public void onChanged(@Nullable List<SubTask> subTasks) {
            //Update RecyclerView
            Log.d(TAG, "onChanged: subTasks length = " + subTasks.size());
            adapter.submitList(subTasks);
        }
    });

SubTaskAdapter.java

public class SubTaskAdapter extends ListAdapter<SubTask, SubTaskAdapter.ViewHolder> {
private static final String TAG = "SubTaskAdapter";

private SubTaskViewModel subTaskViewModel;

public SubTaskAdapter(Context context) {
    super(DIFF_CALLBACK);
    this.context = context;
}

private static final DiffUtil.ItemCallback<SubTask> DIFF_CALLBACK = new DiffUtil.ItemCallback<SubTask>() {
    @Override
    public boolean areItemsTheSame(@NonNull SubTask oldTask, @NonNull SubTask newTask) {
        Log.d(TAG, "areItemsTheSame: oldTask name: " + oldTask.getName() + " id: " + oldTask.getId() + " ### newTask name: " + newTask.getName() + " id: " + newTask.getId());
        return oldTask.getId() == newTask.getId();
    }

    @Override
    public boolean areContentsTheSame(@NonNull SubTask oldTask, @NonNull SubTask newTask) {
        Log.d(TAG, "areContentsTheSame: oldTask name: " + oldTask.getName() + " ### newTask name: " + newTask.getName());
        boolean contentsSame = oldTask.getName().equals(newTask.getName()) &&
                oldTask.getDueDate().equals(newTask.getDueDate()) &&
                oldTask.isCompleted() == newTask.isCompleted() &&
                oldTask.getMainTaskId() == (newTask.getMainTaskId());
        Log.d(TAG, "areContentsTheSame: = " + contentsSame);
        return contentsSame;
    }
};

@Override
public void onBindViewHolder(@NonNull ViewHolder viewHolder, int i) {
    SubTask subTask = getItem(i);
    Log.d(TAG, "onBindViewHolder: pos: " + i + " name: " + subTask.getName() + " Is overdue: " + subTask.isOverdue());

    Log.d(TAG, "onBindViewHolder: " + subTask.getName() + " isOverdue = " + subTask.isOverdue());
    //SET BACKGROUND COLOR OF LIST ITEM
    if (subTask.isOverdue()) {
        viewHolder.card.setCardBackgroundColor(context.getResources().getColor(R.color.red));
        viewHolder.subTaskName.setTextColor(context.getResources().getColor(R.color.colorAccent));
        viewHolder.mainTaskName.setTextColor(context.getResources().getColor(R.color.colorAccent));
    }

    if (subTask.isCompleted()) {
        viewHolder.checkBox.setChecked(true);
        Log.d(TAG, "onBindViewHolder: " + subTask.getName() + " set to checked");
    } else {
        viewHolder.checkBox.setChecked(false);
        Log.d(TAG, "onBindViewHolder: " + subTask.getName() + " set to unchecked");
    }

    viewHolder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() 
    {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            Log.d(TAG, "onCheckedChanged: called for subTask " + subTask.getName() + " isChecked = " + isChecked);
            subTaskViewModel = ViewModelProviders.of((FragmentActivity) context).get(SubTaskViewModel.class);
            if (isChecked) {
                subTask.setCompleted(true);
                subTaskViewModel.updateSubTask(subTask);
            } else {
                subTask.setCompleted(false);
                subTaskViewModel.updateSubTask(subTask);
            }
        }
    });

我遇到的第一个问题是当用户选中列表项的复选框时，列表项变为灰色 like so。这不是预期的行为，因为列表项的颜色不应该在检查时改变。取消选中时不会发生这种情况。

这是此操作的日志：

2020-01-19 15:24:47.572 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onCheckedChanged: called for subTask Test 1 isChecked = true
2020-01-19 15:24:47.575 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskViewModel: updateSubTask: CALLED for Test 1 isCompleted = true isOverdue = false
2020-01-19 15:24:47.602 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskFragment: onChanged: subTasks length = 5
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read database book id: 1 ### newTask name: Read database book id: 1
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read database book id: 1 ### newTask name: Read database book id: 1
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Wash car ### newTask name: Wash car
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read OS book ### newTask name: Read OS book
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read database book ### newTask name: Read database book
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 1 ### newTask name: Test 1
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = false
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 2 ### newTask name: Test 2
2020-01-19 15:24:47.603 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:47.652 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: pos: 3 name: Test 1 Is overdue: false
2020-01-19 15:24:47.652 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: Test 1 isOverdue = false
2020-01-19 15:24:47.655 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: Test 1 set to checked
2020-01-19 15:24:50.633 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onCheckedChanged: called for subTask Test 1 isChecked = false
2020-01-19 15:24:50.633 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskViewModel: updateSubTask: CALLED for Test 1 isCompleted = false isOverdue = false
2020-01-19 15:24:50.664 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskFragment: onChanged: subTasks length = 5
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read database book id: 1 ### newTask name: Read database book id: 1
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read database book id: 1 ### newTask name: Read database book id: 1
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:24:50.664 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Wash car ### newTask name: Wash car
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read OS book ### newTask name: Read OS book
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read database book ### newTask name: Read database book
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 1 ### newTask name: Test 1
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 2 ### newTask name: Test 2
2020-01-19 15:24:50.665 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true

我遇到的下一个可能相关的问题是列表项是 "overdue"（红色任务）and I check it off, other items in the ListAdapter turn red when I hit it's corresponding checkbox。这不是它应该运行的方式。这些列表项应该是白色的，因为这些任务没有过期。当我第二次 check/uncheck 它最终又变回白色。

检查过期任务时应用程序正常运行。它已从屏幕上删除，因为我的 SQL SELECT 语句不再返回已检查的逾期任务。

这是我 check/uncheck 两次未过期列表项时的日志（第 3 个 gif）。这里要注意的一件重要事情是，当检查 Test 1 时，areContentsTheSame() 正确 returns false 当列表项被检查时，因为 isCompleted 已从 true 设置为 false。但是，即使 isCompleted 已从 true 设置为 false，即使未选中它，areContentsTheSame() 也会错误地 returns true。此外，即使 isOverdue 为 false，列表项也会突然变成红色：

2020-01-19 15:28:52.071 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onCheckedChanged: called for subTask Test 1 isChecked = true
2020-01-19 15:28:52.072 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskViewModel: updateSubTask: CALLED for Test 1 isCompleted = true isOverdue = false
2020-01-19 15:28:52.104 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskFragment: onChanged: subTasks length = 4
2020-01-19 15:28:52.104 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:52.104 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:52.104 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:52.104 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:52.104 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:52.104 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Wash car ### newTask name: Wash car
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read OS book ### newTask name: Read OS book
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 1 ### newTask name: Test 1
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = false
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 2 ### newTask name: Test 2
2020-01-19 15:28:52.105 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:52.136 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: pos: 2 name: Test 1 Is overdue: false
2020-01-19 15:28:52.137 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: Test 1 isOverdue = false
2020-01-19 15:28:52.137 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: Test 1 set to checked
2020-01-19 15:28:54.080 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onCheckedChanged: called for subTask Test 1 isChecked = false
2020-01-19 15:28:54.081 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskViewModel: updateSubTask: CALLED for Test 1 isCompleted = false isOverdue = false
2020-01-19 15:28:54.102 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskFragment: onChanged: subTasks length = 4
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Wash car ### newTask name: Wash car
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read OS book ### newTask name: Read OS book
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 1 ### newTask name: Test 1
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 2 ### newTask name: Test 2
2020-01-19 15:28:54.103 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:58.480 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onCheckedChanged: called for subTask Test 1 isChecked = true
2020-01-19 15:28:58.481 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskViewModel: updateSubTask: CALLED for Test 1 isCompleted = true isOverdue = false
2020-01-19 15:28:58.498 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskFragment: onChanged: subTasks length = 4
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Wash car ### newTask name: Wash car
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read OS book ### newTask name: Read OS book
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 1 ### newTask name: Test 1
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = false
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 2 ### newTask name: Test 2
2020-01-19 15:28:58.499 27375-27504/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:58.529 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: pos: 2 name: Test 1 Is overdue: false
2020-01-19 15:28:58.529 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: Test 1 isOverdue = false
2020-01-19 15:28:58.529 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onBindViewHolder: Test 1 set to checked
2020-01-19 15:28:59.922 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskAdapter: onCheckedChanged: called for subTask Test 1 isChecked = false
2020-01-19 15:28:59.922 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskViewModel: updateSubTask: CALLED for Test 1 isCompleted = false isOverdue = false
2020-01-19 15:28:59.941 27375-27375/com.johnsorhannus.divideandconquer D/SubTaskFragment: onChanged: subTasks length = 4
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 2 id: 5 ### newTask name: Test 2 id: 5
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Test 1 id: 4 ### newTask name: Test 1 id: 4
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Read OS book id: 2 ### newTask name: Read OS book id: 2
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areItemsTheSame: oldTask name: Wash car id: 3 ### newTask name: Wash car id: 3
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Wash car ### newTask name: Wash car
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Read OS book ### newTask name: Read OS book
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 1 ### newTask name: Test 1
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: oldTask name: Test 2 ### newTask name: Test 2
2020-01-19 15:28:59.941 27375-27409/com.johnsorhannus.divideandconquer D/SubTaskAdapter: areContentsTheSame: = true

我注意到的另一件事是 areItemsTheSame() 为列表中的每个项目调用两次，而 areContentsTheSame() 为每个列表项目仅调用一次。这似乎不是正常行为，因此这可能以某种方式导致了问题。关于这两个问题是否相关以及如何解决它们有什么想法吗？

Answer 1

这里有两个问题。第一个（灰色突出显示）是由于 RecyclerView 的内置默认动画而发生的。当您选中该框时，RecyclerView 会创建一个新的 ViewHolder 并进行淡入淡出。有关如何解决此问题的更多信息，请参阅此 question/answer：

第二个（红色背景）是您的 onBindViewHolder() 方法中的一个错误，它阻止了视图被正确回收：

if (subTask.isOverdue()) {
    viewHolder.card.setCardBackgroundColor(context.getResources().getColor(R.color.red));
    viewHolder.subTaskName.setTextColor(context.getResources().getColor(R.color.colorAccent));
    viewHolder.mainTaskName.setTextColor(context.getResources().getColor(R.color.colorAccent));
}

像这样的每个 if 语句都需要一个 else 案例来将视图设置回正常颜色。如果没有这样的 else，您的红色视图将被回收到另一个位置，颜色不会发生任何变化 back。

调用 LiveData onChanged() 方法时，ListAdapter 项目呈现不正确。 DiffUtil areContentsTheSame() 可能存在问题？

ListAdapter items rendered incorrectly when LiveData onChanged() method is called. Possible issue with DiffUtil areContentsTheSame()?

java

android

listadapter

android-diffutils