我有一个带导航视图的导航抽屉，有四个标签，其中一个是片段，其中包含ViewPager，即是其他片段的主机。一切正常，但是当使用ViewPager从片段切换时，NavigationDrawer的任何其他片段都不会显示任何内容。检查日志，onCreate，onCreateView这些片段被调用，但为什么不显示...谁知道为什么？
NavigationDrawer
public class NavigationDrawerHost extends AppCompatActivity implements
NavigationView.OnNavigationItemSelectedListener {
//буду использовать эту активность как хост под все фрагменты, чтобы верно работал мой drawer!
public static String WHERE_FROM = NavigationDrawerHost.class.getSimpleName();
public static Toolbar toolbar;
public static ProgressBar progressBar;
private DrawerLayout drawer;
private NavigationView navigationView;
private ActionBarDrawerToggle drawerToggle;
private int navItemId;
private static final String NAV_ITEM_ID = "NAV_ITEM_ID";
private TextView userFirstNameTextView, userLastNameTextView;
private ImageView userPhotoImageView;
private VKAccessToken access_token; //токен это информация о правах доступа
private VKApiUser user; //текущий пользователь
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.navigation_drawer_host);
progressBar = (ProgressBar) findViewById(R.id.progressBar);
drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
// Find the toolbar view inside the activity layout
toolbar = (Toolbar) findViewById(R.id.toolbar);
// Set a Toolbar to replace the ActionBar.
setSupportActionBar(toolbar);
//setTitle(R.string.drawer_menu_posts);
// load saved navigation state if present
if (null == savedInstanceState) {
navItemId = R.id.posts_fragment;
} else {
navItemId = savedInstanceState.getInt(NAV_ITEM_ID);
}
// Find our drawer view
navigationView = (NavigationView) findViewById(R.id.nvView);
navigationView.setNavigationItemSelectedListener(this);
// select the correct nav menu item
navigationView.getMenu().findItem(navItemId).setChecked(true);
// если хотим добавить какие-то элементы в наш header,
// то нужно добавить их в layout, а затем инициализировать нижеприведенным способом
// Inflate the header view at runtime
View headerLayout = navigationView.inflateHeaderView(R.layout.nav_header);
// We can now look up items within the header if needed
userFirstNameTextView = (TextView) headerLayout.findViewById(R.id.user_first_name);
userLastNameTextView = (TextView) headerLayout.findViewById(R.id.user_last_name);
userPhotoImageView = (ImageView) headerLayout.findViewById(R.id.user_photo);
drawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.drawer_open, R.string.drawer_close);
// Tie DrawerLayout events to the ActionBarToggle
drawer.setDrawerListener(drawerToggle);
drawerToggle.syncState();
selectItem(navItemId);
}
@Override
protected void onSaveInstanceState(final Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(NAV_ITEM_ID, navItemId);
}
// Menu icons are inflated just as they were with actionbar
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_exit:
//quitDialog();
VKSdk.logout();
finish();
return true;
default:
return drawerToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
}
}
// Make sure this is the method with just `Bundle` as the signature
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
drawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggles
drawerToggle.onConfigurationChanged(newConfig);
}
private void selectItem(final int itemId) {
// perform the actual navigation logic, updating the main content fragment etc
// Create a new fragment and specify the planet to show based on position
Fragment fragment = null;
Class fragmentClass = null;
switch (itemId) {
case R.id.posts_fragment:
fragmentClass = PostsFragment.class;
fragment = new PostsFragment();
break;
case R.id.albums_fragment:
fragmentClass = FragmentTest.class;
fragment = new FragmentTest();
break;
case R.id.friends_fragment:
fragmentClass = FragmentTest.class;
fragment = new FragmentTest();
break;
case R.id.likes_fragment:
fragmentClass = LikesFragment.class;
fragment = new LikesFragment();
break;
/*default:
fragmentClass = PostsFragment.class;*/
}
/*try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}*/
// Insert the fragment by replacing any existing fragment
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.fragment_container, fragment);
transaction.addToBackStack(null);
transaction.commit();
drawer.closeDrawers();
}
@Override
public boolean onNavigationItemSelected(final MenuItem item) {
// update highlighted item in the navigation menu
item.setChecked(true);
setTitle(item.getTitle());
navItemId = item.getItemId();
// allow some time after closing the drawer before performing real navigation
// so the user can see what is happening
drawer.closeDrawer(GravityCompat.START);
selectItem(item.getItemId());
return true;
}
@Override
public void onBackPressed() {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
quitDialog();
} else {
getSupportFragmentManager().popBackStack();
}
}
private void quitDialog() {
AlertDialog.Builder quitDialog = new AlertDialog.Builder(this);
quitDialog.setTitle("Вы хотите выйти?");
quitDialog.setPositiveButton("Да", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//стираем БД
Delete.tables(PostTable.class, PictureTable.class, PostTableMyLikes.class, PictureTableMyLikes.class);
FlowManager.getDatabase(WallDatabase.DB_NAME).reset(NavigationDrawerHost.this);
FlowManager.getDatabase(WallDatabaseMyLikes.DB_NAME).reset(NavigationDrawerHost.this);
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
});
quitDialog.setNegativeButton("Нет",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
});
quitDialog.show();
}
}
ViewPager主机片段，需要通过ViewPager显示
//этот фрагмент является хостом для MyLikesFragment и FriendLikesFragment, так же тут содержатся табы
public class LikesFragment extends Fragment {
public static String WHERE_FROM_FRIENDS_LIKES = LikesFragment.class.getSimpleName() + "_FRIENDSLIKES";
private ViewPager viewPager;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.likes_fragment, container, false);
TabLayout tabLayout = (TabLayout) v.findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("Мои лайки"));
tabLayout.addTab(tabLayout.newTab().setText("Лайки друзей"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
viewPager = (ViewPager) v.findViewById(R.id.view_pager);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
viewPager.setAdapter(new LikesPagerAdapter(getChildFragmentManager()));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
return v;
}
public static class LikesPagerAdapter extends FragmentPagerAdapter {
public LikesPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public int getCount() {
return 2;
}
//сделано так, чтобы передавать те аргументы, от которых будет зависеть функционал фрагмента
@Override
public Fragment getItem(int position) {
return (position == 0) ? new MyLikesPostsFragment() : new PostsFragment();
}
@Override
public CharSequence getPageTitle(int position) {
return (position == 0) ? "Мои лайки" : "Лайки друзей";
}
}
}
P.S。在转到相同的片段ViewPager后，在抽屉中选择几个项目，这不应该是
答案 0 :(得分：1)
问题是我在主线程中调用了adapter.notifyDataSetChanged()而在AsyncTask中调用了onPostExecute()。我的粗心......