我正在学习Android MVP体系结构here。基于这个例子,我创建了我自己的简单应用程序,它只显示带有拉动功能的列表recyclerview
。Android MVP体系结构 - 存储库和视图之间的通信
当列表被拉出时,我首先要清除recyclerview,然后再次从存储库重新加载数据(使用假等待时间延迟)。但是,当我清除RecyclerViewAdpater中的数据时,存储库中的所有数据也将被清除,并且不会显示任何内容。我只是不明白原因。
这里是我的活动,既创造演示和视图(即片段):
protected void onCreate(Bundle savedInstanceState) {
mainFragment = MainFragment.newInstance();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.add(R.id.contentFrame, mainFragment);
transaction.commit();
new MainPresenter(new MainDataRepository(), mainFragment);
}
这里是我的片段(MainFragment) - 注意: updateList(空) - 这是它会清除所有数据,包括内部存储库:
public MainFragment() {
}
public static MainFragment newInstance() {
return new MainFragment();
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
//....
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
recyclerAdapter.updateList(null); // **This is where it clears all data, including inside Repository**
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
mPresenter.loadList(); // to reload the list
}
}, 1500);
}
});
//...
}
@Override
public void onResume() {
super.onResume();
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
mPresenter.loadList();
}
}, 3000);
}
@Override
public void setPresenter(MainContractor.Presenter presenter) {
mPresenter = presenter;
}
@Override
public void showList(List<String> mainDataList) {
if(recyclerAdapter == null) {
recyclerAdapter = new RecyclerAdapter(mainDataList);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
recyclerView.setAdapter(recyclerAdapter);
}else{
recyclerAdapter.updateList(mainDataList);
}
}
这里是我的演讲(MainPresenter):
public MainPresenter(MainDataRepository mainDataRepository, MainContractor.View view){
mMainDataRepository = mainDataRepository;
mMainContractorView = view;
view.setPresenter(this);
}
@Override
public void loadList() {
ArrayList<String> strings = mMainDataRepository.getList();
mMainContractorView.showList(strings);
}
这里是我的仓库(MainDataRepository):
private ArrayList<String> repositoryList;
public MainDataRepository() {
createList();
}
private void createList() {
if(repositoryList == null){
repositoryList = new ArrayList<>();
}
for (int i = 1; i <= 10; i++) {
repositoryList.add("Item " + i);
}
}
public ArrayList<String> getList(){
return repositoryList;
}
,最后一个,这就是我更新recyclerview内RecyclerAdapter:
public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.MyViewHolder> {
private List<String> stringsList;
public RecyclerAdapter(List<String> stringsList) {
this.stringsList = stringsList;
}
public void updateList(List<String> newStrings){
if(newStrings != null){
stringsList = newStrings;
}else{
stringsList.clear();
}
notifyDataSetChanged();
}
//....
}
为什么里面RecyclerAdapter updateList mehod也会清除内部存储库中的数据那是ArrayList<String> repositoryList
?
你可以看看这个示例项目http://github.com/mmirhoseini/marvel和本文https://hackernoon.com/yet-another-mvp-article-part-1-lets-get-以了解项目d3fd553b3e21以更熟悉MVP。 –