android - 如何将 rest api 列表传递给 android 中的 fragment Activity

Question

我有 MainActivity 和三个 fragment Activity 。在 MainActivity 中，它从 REST 服务调用中获取数据。我想将 REST 数据传递给所有三个 fragment 。如何实现？

这是我的代码

主 Activity

public class MainActivity extends AppCompatActivity {

private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
private CustomListAdapter adapter;
private static final String TAG = MainActivity.class.getSimpleName();



public List<MenuItem> mainList = new ArrayList<MenuItem>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

          JsonArrayRequest itemReq = new JsonArrayRequest(url,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d(TAG, response.toString());
                    try {

                            JSONArray jsonArray = response.getJSONArray(0);
                            // Parsing json
                            for (int i = 0; i < jsonArray.length(); i++) {
                                try {
                                    JSONObject obj = jsonArray.getJSONObject(i);
                                    MenuItem menuItem = new MenuItem();
                                    menuItem.setName(obj.getString("name"));
                                    menuItem.setImage(obj.getString("image"));
                                    menuItem.setPrice(obj.getString("price"));
                                    menuItem.setDesc(obj.getString("desc"));

                                    mainList.add(menuItem);

                                } catch (JSONException e) {
                                    e.printStackTrace();
                                }

                            }

                    }catch (JSONException e){

                    }
                    // notifying list adapter about data changes
                    // so that it renders the list view with updated data
                    adapter.notifyDataSetChanged();
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            VolleyLog.d(TAG, "Error: " + error.getMessage());
             hidePDialog();

        }
    });

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    viewPager = (ViewPager) findViewById(R.id.viewpager);
    setupViewPager(viewPager);

    tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(viewPager);
}




private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
    adapter.addFragment(new First(), "FIRST");
    adapter.addFragment(new Second(), "SECOND");
    adapter.addFragment(new Third(), "THIRD");
    viewPager.setAdapter(adapter);
}

class ViewPagerAdapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFragment(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}

fragment Activity

public class First extends Fragment{
    private ProgressDialog pDialog;
    private GridView gridView;
    private CustomListAdapter adapter;
    public First() {

    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view =  inflater.inflate(R.layout.fragment_one, container, false);

        gridView = (GridView) view.findViewById(R.id.list);
        adapter = new CustomListAdapter(getActivity(), startersList);
        gridView.setAdapter(adapter);
        return view;
    }
}

在这一行 adapter = new CustomListAdapter(getActivity(), startersList);我想从 MainActivity 获取列表数据

Answer 1

如果你能让你的菜单项类实现 Parcelable

How can I make my custom objects Parcelable?

然后就是将参数传递给 Fragment 了

Bundle args = new Bundle();
args.putParcelableArrayList("list", mainList) ;
Fragment first = new First();
first.setArguments(first);
adapter.addFragment(first, "FIRST");

在 Fragment 中，您将使用

 getArguments().getParcelableArrayList("list")

或者，您也可以将 JSON 字符串传递到参数中并在 Fragment 中解析它。

注意:但是，这仅在您在 onResponse 中移动 viewpager 设置方法时才有效。否则，您的 fragment 已经用空列表创建。

或者您可以在适配器中实现上述逻辑

@Override
public Fragment getItem(int position) {
    Fragment f = mFragmentList.get(position);
    // TODO  f.setArguments() 
   return f;
}