我无法在活动的片段中填充 recyclerview

Question

我正在从 ActivityA 获取数据并尝试访问 fragment 方法来填充 RecyclerView。

在Activity中设置TabLayout方法；

private void setTabLayout(String key, String content) {
    //Create Fragment
    SearchPostFragment fragment = new SearchPostFragment();
    Bundle bundle = new Bundle();
    bundle.putString("key", key);
    bundle.putString("content", content);
    fragment.setArguments(bundle);
    //init
    tabLayout = findViewById(R.id.search_activity_tab);
    viewPager = findViewById(R.id.search_activity_container);
    adapter = new SettingsViewAdapter(getSupportFragmentManager());
    //Add Fragments
    adapter.addFragment(fragment, getString(R.string.activity_search_tablayout_post_title));
    adapter.addFragment(new SearchUserFragment(), getString(R.string.activity_search_tablayout_user_title));
    //Setup Adapter
    viewPager.setAdapter(adapter);
    tabLayout.setupWithViewPager(viewPager);
}

我在我的Activity onCreate()上使用这个Set Up TabLayout方法来设置，首先给null；

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);
        setTabLayout(null, null);
    }

然后我从 EditText 键侦听器调用 fragment 方法；

    searchET.setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER)) {
                //Pressed Enter
                String searchText = searchET.getText().toString();
                if (!searchText.trim().equals("")){
                    switch (tabLayout.getSelectedTabPosition()){
                        case 0: //Post
                            SearchPostFragment fragment = new SearchPostFragment();
                            fragment.searchPost(key, content);
                            break;
                        case 1: //User

                            break;
                    }
                }
                return true;
            }
            return false;
        }
    });

Fragment方法看起来像；

public void searchPost(String key, String content) {
        Call<SearchResponse> call = RetrofitClient.getInstance().getApi().getSearch(key, content);
        call.enqueue(new Callback<SearchResponse>() {
            @Override
            public void onResponse(Call<SearchResponse> call, Response<SearchResponse> response) {
                try {
                    if (!response.body().isError()) {
                        searchList = response.body().getSearch();
                        adapter = new SearchPostAdapter(getActivity(), searchList);
                        recyclerView.setAdapter(adapter);
                    }
                } catch (NullPointerException e) {
                    Log.d(TAG, "onResponse: " + e.getMessage());
                }
            }

            @Override
            public void onFailure(Call<SearchResponse> call, Throwable t) {
                Log.d(TAG, "onFailure: " + t.getMessage());
            }
        });
    }

我得到了；

onResponse: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setAdapter(android.support.v7.widget.RecyclerView$Adapter)' on a null object reference

但如果我在我的 fragment 中调用该 method，就像在 onViewCreated 中一样，一切都会顺利进行。 我尝试发送 context 或在 onAttach 中获取上下文，但这些都不起作用

我正在使用 Tab Layout 结构。

我的应用看起来像 https://i.ibb.co/mCy6PS8/photo5951987656600695037.jpg

如果您需要，我可以为您提供更多信息

我解决了这个问题；

EditText OnKeyListener

Fragment searchPostFragment = (SearchPostFragment)getSupportFragmentManager().getFragments().get(0);
((SearchPostFragment) searchPostFragment).searchPost(key, content);

感谢您的帮助

Answer 1

您必须为片段创建实例方法。

    public static SearchPostFragment  newInstance(String key,String content) {
    SearchPostFragment searchFragment = new SearchPostFragment();
    Bundle args = new Bundle();
    args.putString("key_1", key);
    args.putString("key_2", content);
    searchFragment.setArguments(args);
    return searchFragment;

}

在片段调用方法的 OnCreate 方法中，如下所示。

OnCreate(){

   //Write those things below of your recycler view initialization

    String key  = getArguments().getInt("key_1","");
    String content  = getArguments().getInt("key_2", "");
    searchPost(key, content);


}

从这样的活动中调用片段：-

SearchPostFragment.newInstance(key,content);

Answer 2

您遇到的错误是因为片段视图尚未膨胀。您应该考虑通过参数传递这些数据。

在您的活动中：

SearchPostFragment fragment = new SearchPostFragment();
Bundle bundle = new Bundle();
bundle.putString("key", key);
bundle.putString("content", content);
fragment.setArguments(bundle);
// then do the fragment transaction

SearchFragment.java

public class SearchPostFragment extends Fragment {

    RecyclerView recyclerView;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_layout, container, false);
        // replace fragment_layout with your fragment view
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        recyclerView = view.findViewById(R.id.recycler_view);
        // replace recycler_view with your view id

        Bundle args = getArguments();
        if (args != null) {
            String key = args.getString("key");
            String content = args.getString("content");
            if (key != null && content != null) {
                makeApiCall(key, content);
            }
        }
    }

    void makeApiCall(String key, String content) {
        Call<SearchResponse> call = RetrofitClient.getInstance().getApi().getSearch(key, content);
        call.enqueue(new Callback<SearchResponse>() {
            @Override
            public void onResponse(Call<SearchResponse> call, Response<SearchResponse> response) {
                try {
                    if (!response.body().isError()) {
                        searchList = response.body().getSearch();
                        adapter = new SearchPostAdapter(getActivity(), searchList);
                        recyclerView.setAdapter(adapter);
                    }
                } catch (NullPointerException e) {
                    Log.d(TAG, "onResponse: " + e.getMessage());
                }
            }

            @Override
            public void onFailure(Call<SearchResponse> call, Throwable t) {
                Log.d(TAG, "onFailure: " + t.getMessage());
            }
        });
    }
}

Answer 3

Recycler 视图的问题当您从其他类调用静态方法时，通常会出现问题，因为最佳解决方案是 您可以实现接口。 或

您可以尝试在改造响应中初始化回收站视图。

         try {

                recyclerView=findViewById(R.id.recyclerView);
                layoutManager=new LinearLayoutManager(context);
                recyclerView.setLayoutManager(layoutManager);

                if (!response.body().isError()) {
                    searchList = response.body().getSearch();
                    adapter = new SearchPostAdapter(getActivity(), searchList);
                    recyclerView.setAdapter(adapter);
                }
            } catch (NullPointerException e) {
                Log.d(TAG, "onResponse: " + e.getMessage());
            }