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Question

新的分页库的所有示例都使用了Room库,Room为我们创建了一个数据源.在我自己的情况下,我需要创建我的自定义数据源.

这是我的视图模型类中应该返回实时数据的方法.我的liveata总是返回null.

 LiveData<PagedList<ApiResult>> getData(){

    LivePagedListProvider<Integer,ApiResult> p = new LivePagedListProvider<Integer, ApiResult>() {
        @Override
        protected DataSource<Integer, ApiResult> createDataSource() {
            return new DataClass();
        }

    };

    listLiveData = p.create(0,new PagedList.Config.Builder()
            .setPageSize(5) //number of items loaded at once
            .setPrefetchDistance(0)// the distance to the end of already loaded list before new data is loaded
            .build());
    return listLiveData;
}

这是Data类

public class DataClass extends TiledDataSource<ApiResult> {

    private List<ApiResult> result = new ArrayList<>();

    @Override
    public int countItems() {
        return result.size();
    }

    @Override
    public List<ApiResult> loadRange(int startPosition, int count) {

        Call<String> call = NetworkModule.providesWebService().makeRequest();
        call.enqueue(new Callback<String>() {
            @Override
            public void onResponse(@NonNull Call<String> call, @NonNull Response<String> response) {
                Log.i(DataClass.this.getClass().getSimpleName() + " - onResponse", String.valueOf(response));
                result = parseJson(response.body());
            }

            @Override
            public void onFailure(@NonNull Call<String> call, @NonNull Throwable t) {
                Log.i(DataClass.this.getClass().getSimpleName() + " - onFailure", t.getMessage());
            }

        });

        return result;
    }

}

Answer 1

我认为这可以提供帮助:
1.countItems()应返回DataSource.COUNT_UNDEFINED
2. loadRange(int startPosition,int count):您可以直接执行查询.
所以现在你可以删除结果全局变量

另外,关闭占位符:

listLiveData = p.create(0,new PagedList.Config.Builder()
        .setPageSize(5) //number of items loaded at once
        .setPrefetchDistance(10) //Must be >0 since placeholders are off
        .setEnablePlaceholders(false)
        .build());

以下是Data Class的更新代码:

public class DataClass extends TiledDataSource<ApiResult> {

@Override
public int countItems() {
 return DataSource.COUNT_UNDEFINED;
}

@Override
public List<ApiResult> loadRange(int startPosition, int count) {

 Call<String> call = NetworkModule.providesWebService().makeRequest();
 Response<String> response = call.execute();
 return parseJson(response.body());
}

您可以在此处查看示例项目:https: //github.com/brainail/.samples/tree/master/ArchPagingLibraryWithNetwork