Question

我在使用recycleView时遇到了一些麻烦。我想使用DiffUtil更新recycleview。但我不明白为什么它不起作用。这是我的DiffUtil

public class ConsumableDiffCallBack extends DiffUtil.Callback {

private List<ConsumableByTask> oldListOfConsumableByTask;
private List<ConsumableByTask> newListOfConsumableByTask;

@Override
public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
    return oldListOfConsumableByTask.get(oldItemPosition).getQuantity() != newListOfConsumableByTask.get(newItemPosition).getQuantity();
}

@Override
public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
    return oldListOfConsumableByTask.get(oldItemPosition).equals(newListOfConsumableByTask.get(newItemPosition));
}}

我的适配器支架

    public class ConsumeHolder extends RecyclerView.ViewHolder {

    private Button addConsumeBtn;

    public ConsumeHolder(View itemView) {
        /**
         * add/change data and send it to server.
         * after close ConsumablesByTaskActivity.
         */
        addConsumeBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //do something

                listener.sendDataAndCloseFrame();
            }
        });}}

适配器类中的更新方法

public void updateList(List<ConsumableByTask> list){
    final ConsumableDiffCallBack consumableDiffCallBack = new ConsumableDiffCallBack(this.consumableByTaskList,list);
    final DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(consumableDiffCallBack);

    this.consumableByTaskList.clear();
    this.consumableByTaskList.addAll(list);

    diffResult.dispatchUpdatesTo(this);
}

活动方法

public void sendDataAndCloseFrame() {
    List<ConsumableByTask> listOfConsumable = //get new list from server;

    adapter.updateList(listOfConsumable);


    finish();
}

感谢。

Answer 1

我在我的RecyclerAdapater中使用它

private List<bindableAssignment> dataBaseItemList;

public void setItems(final List<bindableAssignment> argumentList) {
    if (dataBaseItemList == null) {
        dataBaseItemList = argumentList;
        notifyItemRangeChanged(0, dataBaseItemList.size());
    } else {
        DiffUtil.DiffResult result = DiffUtil.calculateDiff(new DiffUtil.Callback() {
            @Override
            public int getOldListSize() {
                return dataBaseItemList.size();
            }

            @Override
            public int getNewListSize() {
                return argumentList.size();
            }

            @Override
            public boolean areItemsTheSame(int oldItemPosition, int newItemPosition) {
                return dataBaseItemList.get(oldItemPosition).getId() == argumentList.get(newItemPosition).getId();
            }

            @Override
            public boolean areContentsTheSame(int oldItemPosition, int newItemPosition) {
                bindableAssignment oldItem = dataBaseItemList.get(oldItemPosition);
                bindableAssignment newItem = argumentList.get(newItemPosition);
                // Change this to apply your object
                return oldItem.getId() == newItem.getId()
                        && oldItem.getName().equals(newItem.getName())
                        && (oldItem.getDesc() != null && newItem.getDesc() != null) && oldItem.getDesc().equals(newItem.getDesc())
                        && oldItem.getClassId() == newItem.getClassId()
                        && oldItem.getDueTime() == newItem.getDueTime();
            }
        });
        dataBaseItemList = argumentList;
        result.dispatchUpdatesTo(this);
    }
    Log.d("dataBindingAdapter", "Changing data with " + dataBaseItemList.size() + " elements");
}

希望它适合你。

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1 个答案: