我在MainActivity.java中有一个工作的RecyclerView和常规事件的片段“概述”，但我想在一个单独的片段（“提醒”）中实现第二个。在我的MainActivity的OnCreate中，设置了第一个片段，我面临的问题是无法使用setContentView两次。
这是我的MainActivity.java：
public class MainActivity extends AppCompatActivity
implements NavigationDrawerFragment.NavigationDrawerCallbacks {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {@link #restoreActionBar()}.
*/
private CharSequence mTitle;
private RecyclerView mRecyclerView;
private RecyclerView.LayoutManager mLayoutManager;
OverviewAdapter mAdapter;
private RecyclerView reminderRecyclerView;
private RecyclerView.LayoutManager reminderLayoutManager;
RemindersAdapter reminderAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(this);
mRecyclerView.setLayoutManager(mLayoutManager);
events();
mAdapter = new OverviewAdapter(events);
mRecyclerView.setAdapter(mAdapter);
}
@Override
public void onNavigationDrawerItemSelected(int element) {
// update the main content by replacing fragments
FragmentManager fragmentManager = getSupportFragmentManager();
Fragment fragment = new Fragment();
element++;
// int frame = R.id.container;
String position = "Overview";
switch(element) {
case 1:
position = "Overview";
mTitle = getString(R.string.title_section1);
// frame = R.id.container;
break;
case 2:
position = "Reminders";
mTitle = getString(R.string.title_section2);
fragment = new Reminders();
setContentView(R.layout.reminder_recycler);
// REMINDERS RECYCLERVIEW SETUP BELOW
setContentView(R.layout.reminder_recycler);
reminderRecyclerView = (RecyclerView) findViewById(R.id.my_reminder_recycler_view);
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
reminderRecyclerView.setHasFixedSize(true);
reminderEvents();
// use a linear layout manager
reminderLayoutManager = new LinearLayoutManager(this);
reminderRecyclerView.setLayoutManager(reminderLayoutManager);
reminderAdapter = new RemindersAdapter(reminderEventsList);
reminderRecyclerView.setAdapter(reminderAdapter);
break;
case 3:
position = "Categories";
mTitle = getString(R.string.title_section3);
fragment = new Categories();
// frame = R.id.categories;
break;
case 4:
position = "Smart Suggestions";
mTitle = getString(R.string.title_section4);
fragment = new SmartSuggestions();
// frame = R.id.smart_suggestions;
break;
}
fragmentManager.beginTransaction()
.replace(R.id.container, fragment)
.commit();
}
}
我在Reminders类中被赋予空指针异常，如下所示：
public class Reminders extends Fragment {
private RecyclerView reminderRecyclerView;
private RecyclerView.LayoutManager reminderLayoutManager;
RemindersAdapter reminderAdapter;
Context context;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.reminders, container, false);
// Inflate the layout for this fragment
return rootView;
}
public List<ReminderEvents> reminderEventsList = new ArrayList<>();
public void reminderEvents() {
reminderEventsList.add(new ReminderEvents("Example reminder", "Wed 12 July"));
reminderEventsList.add(new ReminderEvents("Example reminder1", "Wed 12 July"));
reminderEventsList.add(new ReminderEvents("Example reminder2", "Wed 12 July"));
reminderEventsList.add(new ReminderEvents("Example reminder3", "Wed 12 July"));
}
}