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Navigation Drawer Back Pressed Fragment Doesn't Load

I have a navigation drawer with fragments. At start, I display Home fragment as default.
There are options on navigation menu. In 2 fragments I have SwipeRefreshLayout. Until all recyclerview data are fetched then I display data and invisible SwipeRefreshLayout.
One of these fragments (included SwipeRefReshLayout) works fine but, in Home fragment something is wrong.
For example(use case)
You started app and you saw Home fragment
You clicked Profile fragment on navigation menu
You run onBackPressed(back button).
In this case data never loads and SwipeRefReshLayout is always spinning. (I also tried without refreshlayout, still same)
Any idea how to fix this? My thought is, its about displaying default fragment.
Navigation Drawer Activity
public class Page_Navigation extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
Fragment fragment;
FragmentManager fragmentManager = getSupportFragmentManager();
NavigationView navigationView;
SharedPreferences mSharedPref;
DrawerLayout drawer;
private Tracker mTracker;
FragmentTransaction fragmentTransaction;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_page__navigation);
//
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
TextView toolbar_head = findViewById(R.id.toolbar_head);
ImageView toolbar_image = findViewById(R.id.toolbar_image);
ImageView toolbar_profile = findViewById(R.id.toolbar_profile);
drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
//
AnalyticsApplication application = (AnalyticsApplication) getApplication();
mTracker = application.getDefaultTracker();
mTracker.setScreenName("page_navigation");
mTracker.send(new HitBuilders.ScreenViewBuilder().build());
//FIRST SETTINGS
setSupportActionBar(toolbar);
Typeface customFont = Typeface.createFromAsset(getAssets(), "Montserrat-Medium.ttf");
toolbar_head.setTypeface(customFont);
//Get Sessions
mSharedPref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
String session_user_name = mSharedPref.getString("session_user_name", "");
String session_user_photo = mSharedPref.getString("session_user_photo", "");
//Navigation Drawer
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
navigationView.setItemIconTintList(null);
//
View headerView = navigationView.getHeaderView(0);
TextView nav_userName = (TextView) headerView.findViewById(R.id.textView_nav_userName);
CircleImageView imageView_navigation = (CircleImageView) headerView.findViewById(R.id.imageView_navigation);
Glide.with(getApplicationContext()).load(session_user_photo).into(imageView_navigation);
nav_userName.setText(session_user_name);
headerView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (drawer.isDrawerOpen(Gravity.START)) {
drawer.closeDrawer(Gravity.START);
}
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
showProfileFragment();
}
}, 300);
}
});
toolbar_image.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
drawer.openDrawer(GravityCompat.START);
}
});
toolbar_profile.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Fragment fragment;
FragmentManager manager = getSupportFragmentManager();
fragment = new Nav_Profile();
fragmentTransaction = manager.beginTransaction();
fragmentTransaction.replace(R.id.navContent, fragment).addToBackStack(null).commit();
}
});
displayDefaultFragment();
}
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.page__navigation, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
final int id = item.getItemId();
drawer.closeDrawer(GravityCompat.START);
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
switch (id) {
case R.id.nav_home:
fragment = new Nav_Home();
break;
case R.id.nav_contact:
fragment = new Nav_Contact();
break;
case R.id.nav_articles:
fragment = new Nav_Article();
break;
case R.id.nav_about:
fragment = new Nav_AboutUs();
break;
case R.id.nav_suggest:
fragment = new Nav_Suggest();
break;
case R.id.nav_share:
fragment = new Nav_Share();
break;
case R.id.nav_rateApp:
fragment = new Nav_RateApp();
break;
}
fragmentManager.beginTransaction()
.replace(R.id.navContent, fragment)
.addToBackStack(null)
.commit();
}
}, 350);
return true;
}
public void displayDefaultFragment() {
fragment = new Nav_Home();
fragmentManager.beginTransaction().replace(R.id.navContent, fragment).commit();
}
public void showProfileFragment() {
fragment = new Nav_Profile();
fragmentManager.beginTransaction().replace(R.id.navContent, fragment).addToBackStack(null).commit();
}
}
Home Fragment
public class Nav_Home extends Fragment implements View.OnClickListener{
SharedPreferences mSharedPref;
private SwipeRefreshLayout swipeRefresh_home;
private CardView item_homeTop_coupons, item_homeTop_draws, item_homeTop_event;
private LinearLayout layout_all_article, layout_all_999;
private ScrollView shimmer_home;
private List<Model_ListItem> listNewItems;
private RecyclerView recyclerView_item_home;
private List<Model_Article> articleList;
private RecyclerView recyclerView_article_home;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
fetchItemsNew();
fetchArticlesNew();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_nav__home, container, false);
item_homeTop_coupons = view.findViewById(R.id.item_homeTop_coupons);
item_homeTop_draws = view.findViewById(R.id.item_homeTop_draws);
item_homeTop_event = view.findViewById(R.id.item_homeTop_event);
recyclerView_item_home = view.findViewById(R.id.recyclerView_item_home);
recyclerView_article_home = view.findViewById(R.id.recyclerView_article_home);
layout_all_article = view.findViewById(R.id.layout_all_article);
layout_all_999 = view.findViewById(R.id.layout_all_999);
swipeRefresh_home = view.findViewById(R.id.swipeRefresh_home);
shimmer_home = view.findViewById(R.id.shimmer_home);
item_homeTop_coupons.setOnClickListener(this);
item_homeTop_draws.setOnClickListener(this);
item_homeTop_event.setOnClickListener(this);
layout_all_999.setOnClickListener(this);
layout_all_article.setOnClickListener(this);
//first settngs
mSharedPref = PreferenceManager.getDefaultSharedPreferences(view.getContext());
String session_user_email = mSharedPref.getString("session_user_email","");
swipeRefresh_home.setRefreshing(true);
return view;
}
#Override
public void onClick(View v) {
switch (v.getId()){
case R.id.item_homeTop_coupons:
startActivity(new Intent(getContext(), Page_Coupon.class));
break;
case R.id.item_homeTop_draws:
startActivity(new Intent(getContext(), Page_Draw.class));
break;
case R.id.item_homeTop_event:
startActivity(new Intent(getContext(), Page_Event.class));
break;
case R.id.layout_all_999:
//999 city search activity
startActivity(new Intent(getContext(), Page_SearchCity.class));
break;
case R.id.layout_all_article:
//article fragment
Fragment fragment;
FragmentManager fragmentManager = getFragmentManager();
fragment = new Nav_Article();
fragmentManager.beginTransaction().replace(R.id.navContent, fragment).addToBackStack(null).commit();
break;
}
}
public void fetchItemsNew(){
listNewItems = new ArrayList<>();
API_Service api_service = Client.getRetrofitInstance().create(API_Service.class);
Call<List<Model_ListItem>> call = api_service.fetchItemsNew();
call.enqueue(new Callback<List<Model_ListItem>>() {
#Override
public void onResponse(Call<List<Model_ListItem>> call, Response<List<Model_ListItem>> response) {
if(response.code() == 200){
listNewItems = response.body();
Adapter_HomeItem adapter_homeItem = new Adapter_HomeItem(getContext(), listNewItems);
LinearLayoutManager layoutManager
= new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false);
recyclerView_item_home.setHasFixedSize(true);
recyclerView_item_home.setLayoutManager(layoutManager);
recyclerView_item_home.setAdapter(adapter_homeItem);
SnapHelper helper = new LinearSnapHelper();
helper.attachToRecyclerView(recyclerView_item_home);
}
}
#Override
public void onFailure(Call<List<Model_ListItem>> call, Throwable t) {
}
});
}
public void fetchArticlesNew(){
articleList = new ArrayList<>();
API_Service api_service = Client.getRetrofitInstance().create(API_Service.class);
Call<List<Model_Article>> callArticle = api_service.fetchArticlesNew();
callArticle.enqueue(new Callback<List<Model_Article>>() {
#Override
public void onResponse(Call<List<Model_Article>> call, Response<List<Model_Article>> response) {
if(response.code() == 200){
articleList = response.body();
Adapter_HomeArticles adapter_homeArticles = new Adapter_HomeArticles(getContext(), articleList);
LinearLayoutManager layoutManager
= new LinearLayoutManager(getActivity(), LinearLayoutManager.HORIZONTAL, false);
recyclerView_article_home.setLayoutManager(layoutManager);
recyclerView_article_home.setHasFixedSize(true);
recyclerView_article_home.setAdapter(adapter_homeArticles);
}
}
#Override
public void onFailure(Call<List<Model_Article>> call, Throwable t) {
}
});
}
}

Firstly you must disable SwipeRefreshLayout spinning when successfully or not fetched data:
swipeRefresh_home.setRefreshing(false);
If you do not do this spinner will be spinning all the time.
Another problem is that you have one fragment and you try to assign to it Nav_Home fragment and Nav_Profile fragment.
Fragment fragment;
public void displayDefaultFragment() {
fragment = new Nav_Home();
fragmentManager.beginTransaction().replace(R.id.navContent, fragment).commit();
}
public void showProfileFragment() {
fragment = new Nav_Profile();
fragmentManager.beginTransaction().replace(R.id.navContent, fragment).addToBackStack(null).commit();
}
Try to separate them and show like this:
Fragment homeFragment;
Fragment profileFragment;
public void displayDefaultFragment() {
homeFragment = new Nav_Home();
fragmentManager.beginTransaction().replace(R.id.navContent, homeFragment).commit();
}
public void showProfileFragment() {
profileFragment = new Nav_Profile();
fragmentManager.beginTransaction().replace(R.id.navContent, profileFragment).addToBackStack(null).commit();
}

What is going on with my Android Navigation drawer activity?

I am building an OpenGL live wallpaper. I decided to have a Navigation Drawer in my main activity since there are a lot of features the user will have access to.
The problem/issue
If I press the "hardware" back button to normally close an app the initial fragment that is shown just refreshes and the app never closes. If I hit the home button and go back to the app everything is a black screen. I've searched all throughout Google thinking that maybe I wasn't destroying the MainActivity properly or for a way to terminate a fragment. I've tried calling finish() in the main activity's onDestroy method. I've tried utilizing the remove method from fragment manager in each fragments onDetach method per posts that I've found online. Nothing has worked. I'm stumped. I've set debug points in the main activity on the onDestroy method and on the fragments onDetach method with no error being produced or any information being given. At this point I am clueless. Here's my MainActivity class.
public class MainActivity extends AppCompatActivity implements OnNavigationItemSelectedListener, OnPostSelectedListener{
FragmentManager mFragmentManager;
FragmentTransaction mFragmentTransaction;
TextView usrTag, tagrEmail;
CircleImageView tagrPic;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
mFragmentManager = getSupportFragmentManager();
mFragmentTransaction = mFragmentManager.beginTransaction();
mFragmentTransaction.add(R.id.cLMain, new PreviewFragment()).addToBackStack("PreviewFragment").commit();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
View header = navigationView.getHeaderView(0);
usrTag = (TextView)header.findViewById(R.id.usrName);
tagrEmail = (TextView)header.findViewById(R.id.usrEmail);
tagrPic = (CircleImageView)header.findViewById(R.id.usrImg);
Log.i("MainActivity: ", "User Photo: " + getProfilePic(this));
usrTag.setText(getUserName(getBaseContext()));
tagrEmail.setText(getUserEmail(getBaseContext()));
GlideUtils.loadProfileIcon(getProfilePic(getBaseContext()), tagrPic);
}
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
Fragment fragment = null;
Class fragmentClass = null;
int id = item.getItemId();
if (id == R.id.nav_home) {
fragmentClass = PreviewFragment.class;
} else if (id == R.id.nav_custom) {
startCustomLabelCreator();
} else if (id == R.id.nav_mylabels) {
} else if (id == R.id.nav_commLabels) {
fragmentClass = PostsFragment.class;
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
// Insert the fragment by replacing any existing fragment
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.cLMain, fragment).commit();
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
public void startCustomLabelCreator(){
Intent cLC = new Intent(getBaseContext(), CreateLabel.class);
startActivity(cLC);
}
#Override
public void onPostComment(String postKey) {
}
#Override
public void onPostLike(String postKey) {
}
#Override
public void onPhotoSelected(String photoUrl) {
}
#Override
protected void onDestroy() {
super.onDestroy();
finish();
}
}
My Fragments
public class PostsFragment extends Fragment implements ConfirmSelectedPhotoListener{
public static final String TAG = "PostsFragment";
private static final String KEY_LAYOUT_POSITION = "layoutPosition";
private int mRecyclerViewPosition = 0;
private OnPostSelectedListener mListener;
private RecyclerView mRecyclerView;
private RecyclerView.Adapter<PostViewHolder> mAdapter;
public PostsFragment() {
// Required empty public constructor
}
public static PostsFragment newInstance() {
PostsFragment fragment = new PostsFragment();
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_posts, container, false);
rootView.setTag(TAG);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
return rootView;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
linearLayoutManager.setReverseLayout(true);
linearLayoutManager.setStackFromEnd(true);
mRecyclerView.setLayoutManager(linearLayoutManager);
Log.d(TAG, "Restoring recycler view position (all): " + mRecyclerViewPosition);
Query allPostsQuery = FirebaseUtil.getPostsRef();
mAdapter = getFirebaseRecyclerAdapter(allPostsQuery);
mAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
#Override
public void onItemRangeInserted(int positionStart, int itemCount) {
super.onItemRangeInserted(positionStart, itemCount);
// TODO: Refresh feed view.
}
});
mRecyclerView.setAdapter(mAdapter);
}
private FirebaseRecyclerAdapter<Post, PostViewHolder> getFirebaseRecyclerAdapter(Query query) {
return new FirebaseRecyclerAdapter<Post, PostViewHolder>(
Post.class, R.layout.post_item, PostViewHolder.class, query) {
#Override
public void populateViewHolder(final PostViewHolder postViewHolder,
final Post post, final int position) {
setupPost(postViewHolder, post, position, null);
}
#Override
public void onViewRecycled(PostViewHolder holder) {
super.onViewRecycled(holder);
// FirebaseUtil.getLikesRef().child(holder.mPostKey).removeEventListener(holder.mLikeListener);
}
};
}
private void setupPost(final PostViewHolder postViewHolder, final Post post, final int position, final String inPostKey) {
postViewHolder.setPhoto(post.getThumb_url());
Log.d(TAG, post.getThumb_url());
postViewHolder.setText(post.getText());
postViewHolder.setTimestamp(DateUtils.getRelativeTimeSpanString(
(long) post.getTimestamp()).toString());
final String postKey;
if (mAdapter instanceof FirebaseRecyclerAdapter) {
postKey = ((FirebaseRecyclerAdapter) mAdapter).getRef(position).getKey();
} else {
postKey = inPostKey;
}
Author author = post.getAuthor();
postViewHolder.setAuthor(author.getFull_name(), author.getUid());
postViewHolder.setIcon(author.getProfile_picture(), author.getUid());
ValueEventListener likeListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
postViewHolder.setNumLikes(dataSnapshot.getChildrenCount());
if (dataSnapshot.hasChild(FirebaseUtil.getCurrentUserId())) {
postViewHolder.setLikeStatus(PostViewHolder.LikeStatus.LIKED, getActivity());
} else {
postViewHolder.setLikeStatus(PostViewHolder.LikeStatus.NOT_LIKED, getActivity());
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
};
FirebaseUtil.getLikesRef().child(postKey).addValueEventListener(likeListener);
postViewHolder.mLikeListener = likeListener;
postViewHolder.setPostClickListener(new PostViewHolder.PostClickListener() {
#Override
public void showComments() {
Log.d(TAG, "Comment position: " + position);
mListener.onPostComment(postKey);
}
#Override
public void toggleLike() {
Log.d(TAG, "Like position: " + position);
mListener.onPostLike(postKey);
}
#Override
public void savePhotoUrl() {
//mListener.onPhotoSelected(post.getFull_url());
showLabelConfirm(post.getFull_url());
}
});
}
#Override
public void onDestroy() {
super.onDestroy();
if (mAdapter != null && mAdapter instanceof FirebaseRecyclerAdapter) {
((FirebaseRecyclerAdapter) mAdapter).cleanup();
}
}
#Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save currently selected layout manager.
int recyclerViewScrollPosition = getRecyclerViewScrollPosition();
Log.d(TAG, "Recycler view scroll position: " + recyclerViewScrollPosition);
savedInstanceState.putSerializable(KEY_LAYOUT_POSITION, recyclerViewScrollPosition);
super.onSaveInstanceState(savedInstanceState);
}
private int getRecyclerViewScrollPosition() {
int scrollPosition = 0;
// TODO: Is null check necessary?
if (mRecyclerView != null && mRecyclerView.getLayoutManager() != null) {
scrollPosition = ((LinearLayoutManager) mRecyclerView.getLayoutManager())
.findFirstCompletelyVisibleItemPosition();
}
return scrollPosition;
}
#Override
public void onSelectedPhoto(String selectPhoto) {
mListener.onPhotoSelected(selectPhoto);
}
public interface OnPostSelectedListener {
void onPostComment(String postKey);
void onPostLike(String postKey);
void onPhotoSelected(String photoUrl);
}
private void showLabelConfirm(String uriBmp) {
FragmentManager fm = getFragmentManager();
PhotoDialogFragment editNameDialogFragment = PhotoDialogFragment.newInstance(uriBmp);
// SETS the target fragment for use later when sending results
editNameDialogFragment.setTargetFragment(PostsFragment.this, 300);
editNameDialogFragment.show(fm, "fragment_edit_name");
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnPostSelectedListener) {
mListener = (OnPostSelectedListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnPostSelectedListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
}
Second Fragment:
public class PreviewFragment extends RajBaseFragment {
#Override
public ISurfaceRenderer createRenderer() {
return new PreviewRenderer(getContext());
}
}
Which extends:
public abstract class RajBaseFragment extends Fragment implements IDisplay, View.OnClickListener {
protected FrameLayout mLayout;
protected ISurface mRajawaliSurface;
protected ISurfaceRenderer mRenderer;
public RajBaseFragment(){
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
// Inflate the view
mLayout = (FrameLayout) inflater.inflate(getLayoutID(), container, false);
mLayout.findViewById(R.id.relative_layout_loader_container).bringToFront();
// Find the TextureView
mRajawaliSurface = (ISurface) mLayout.findViewById(R.id.rajwali_surface);
// Create the loader
mRenderer = createRenderer();
onBeforeApplyRenderer();
applyRenderer();
return mLayout;
}
protected void onBeforeApplyRenderer() {
}
protected void applyRenderer() {
mRajawaliSurface.setSurfaceRenderer(mRenderer);
}
#Override
public void onClick(View v) {
}
#Override
public void onDestroyView() {
super.onDestroyView();
if (mLayout != null)
mLayout.removeView((View) mRajawaliSurface);
}
#Override
public int getLayoutID() {
return R.layout.rajawali_textureview_fragment;
}
}
I've tried all the recommendations below so far and the primary fragment that is set in the MainActivity's onCreate method still gets refreshed/reloaded when the back button is pressed rather than the app exiting/closing.

In your onNavigationItemSelected method, you are replacing the current fragment with fragment even in cases where fragment is null, which has undefined effects. You should not do that.
One fix is to replace this code block:
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
with this one:
if (fragmentClass != null) {
fragment = fragmentClass.newInstance();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.cLMain, fragment).addToBackStack().commit();
}
(and then leave out the fragment transaction below this point).
Also, there is a call to finish in the onDestroy method, which probably is not causing the problem but should be taken out because it does not make any sense there.

#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();
break;
}
return true;
}
replace your onOptionsItemSelected() with mine.

Don't include your first fragment into backstack.
Try to change you fragment transaction line code without addToBackStack
as below:
mFragmentTransaction.add(R.id.cLMain, new PreviewFragment()).commit();
While adding fragment with addToBackStack, this allows back
navigation for added fragment.Because of fragment in backstack,
empty(black) activity layout will be displayed.
Change onBackPressed() as below which automatically close app after if no any Fragment found in FragmentManager:
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
this.finish();
} else {
getSupportFragmentManager().popBackStack();
}
}
Also you can see some similar Q/A on below links which helps you get more idea to solve your problem:
Fragment pressing back button
In Fragment on back button pressed Activity is blank
Transaction of fragments in android results in blank screen
It's solved my blank screen problem. Hope its helps you.

Try this code, hope this helps you, take necessary stuffs which are required for you. Also, try running this project in Android studio, it works.
https://github.com/asifali22/Navigation_Health/blob/master/app/src/main/java/com/thenewboston/mynavigation/MainActivity.java

When user press to back button it'll check fragment manager's backstack and if backstack entity count is bigger than 0 (this means there's a fragment in backstack) it'll popBackStack else it'll finish activity.
If you add your initial fragment to backstack, when user press back button they'll see a blank screen.
Also when you init your activity if you need to put a fragment it's a best practice to check if saved instance state is null. Here i modified some part of your code.
if(savedInstanceState == null){
mFragmentManager = getSupportFragmentManager();
mFragmentTransaction = mFragmentManager.beginTransaction();
mFragmentTransaction.add(R.id.cLMain, new PreviewFragment()).commit();
}
I hope this'll help you. If you still have problem let me know.
Good luck.

create subclass for ISurface and override onKeyDown method like this
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
Log.e("Custom View", "onKeyDown");
//return super.onKeyDown(keyCode, event);
return false;
}

Could be related with the lifecycle...
Try using GLSurfaceView. I believe is easier for what you want, is special for OpenGL rendering and there is plenty information about it. Examples, lifecycle among others. Let me know if helped. If not, please, provide more info.

Android: "onCreatedView" calls every time when going back and "setUserVisibleHint" is not called

In my android application I have a ViewPager and 5 fragments. I previously used viewPager.setCurrentItem() to navigate, but the requirement for navigation animation has changed; For an example in some fragments when a previous fragment is called, we were asked not to show going back (left to right animation), instead show the user their moving to the next fragment (right to left animation). For an example in some cases user has to insert the same data again and again so instead of creating new fragmnets for these, we re-used the existing ones we created- so when the viewPager.setCurrentItem() is calling a fragment in the back (ex: we are now in 20th fragment and we are calling 10th fragment) it goes back and shows left to right animation.
Now we are not using the viewPager.setCurrentItem() method to navigate, instead we use FragmentTransaction. However we did not remove the fragments from the ViewPager anyway, expecting to complete this with minimum work (we are at the end of project when this requirement appeared)
But when we use the FragmentTransaction we have a new issue now. When we come back the onCreateView of fragmnets are getting called all the time! This didn't happen when we were using viewPager.setCurrentItem(). Lot of our code which should run only once are in this onCreateView.
Another issue is setUserVisibleHint() is called only in first fragment and that is also only at the initial run! All of our code which should run every time the fragmnet is displayed is located in this method.
Below is an example code, which demonstrate our issue.
MainActivity.java
public class MainActivity extends FragmentActivity {
private ViewPager viewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager=(ViewPager)findViewById(R.id.viewPager);
viewPager.setAdapter(new MyPagerAdapter2(getSupportFragmentManager()));
viewPager.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
if (viewPager.getCurrentItem() == 0) {
return true;
}
if (viewPager.getCurrentItem() == 1) {
return true;
}
if (viewPager.getCurrentItem() == 2) {
return true;
}
if (viewPager.getCurrentItem() == 3) {
return true;
}
if (viewPager.getCurrentItem() == 4) {
return true;
}
return false;
}
});
}
private class MyPagerAdapter2 extends FragmentPagerAdapter {
public MyPagerAdapter2(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int pos) {
switch(pos) {
case 0: return FirstFragment1.newInstance("FirstFragment_1");
case 1: return SecondFragment1.newInstance("SecondFragment_1");
case 2: return ThirdFragment1.newInstance("ThirdFragment_1");
case 3: return FourthFragment1.newInstance("FourthFragment_1");
case 4: return FifthFragment1.newInstance("FifthFragment_1");
default: return FirstFragment1.newInstance("DefaultFragment_1");
}
}
#Override
public int getCount() {
return 1;
}
}
public void setCurrentItem(int which) {
if(viewPager != null && which >= 0 && which <= 4) {
viewPager.setCurrentItem(which);
}
}
}
FirstFragment1.java
public class FirstFragment1 extends Fragment {
TextView textView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.first_frag_1, container, false);
TextView tv = (TextView) v.findViewById(R.id.tvFragFirst);
tv.setText("FRAGMENT 01");
textView=(TextView)v.findViewById(R.id.textView1);
textView.setText("Fragment Name : - 01");
Log.d("FRAGMENT_01", "ON_CREATE");
Button button1 = (Button) v.findViewById(R.id.nextButton);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (getActivity() != null) {
FragmentManager fragmentManager=getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setCustomAnimations(R.anim.from_right, R.anim.to_left);
transaction.replace(R.id.firstFragment, new SecondFragment1());
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.addToBackStack(null);
transaction.commit();
}
}
});
return v;
}
public static FirstFragment1 newInstance(String text) {
FirstFragment1 f = new FirstFragment1();
Bundle b = new Bundle();
b.putString("msg", text);
f.setArguments(b);
return f;
}
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
Activity a = getActivity();
if (a != null) a.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LOCKED);
// textView.setText("Fragment Name : - 01");
Log.d("FRAGMENT_01", "VISIBLE_HINT");
}
}
}
SecondFragment1.java
public class SecondFragment1 extends Fragment {
TextView textView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.second_frag_1, container, false);
TextView tv = (TextView) v.findViewById(R.id.tvFragSecond);
tv.setText("FRAGMENT 03");
textView=(TextView)v.findViewById(R.id.textView2);
textView.setText("Fragment Name : - 02");
Log.d("FRAGMENT_02", "ON_CREATE");
Button button=(Button)v.findViewById(R.id.printButton);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(getActivity() != null) {
FragmentManager fragmentManager=getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setCustomAnimations(R.anim.from_right, R.anim.to_left);
transaction.replace(R.id.secondFrag, new FirstFragment1());
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.addToBackStack(null);
transaction.commit();
}
}
});
Button button1=(Button)v.findViewById(R.id.nextButton);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (getActivity() != null) {
FragmentManager fragmentManager=getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setCustomAnimations(R.anim.from_right, R.anim.to_left);
transaction.replace(R.id.secondFrag, new ThirdFragment1());
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.addToBackStack(null);
transaction.commit();
}
}
});
return v;
}
public static SecondFragment1 newInstance(String text) {
SecondFragment1 f = new SecondFragment1();
Bundle b = new Bundle();
b.putString("msg", text);
f.setArguments(b);
return f;
}
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if(isVisibleToUser) {
Activity a = getActivity();
if(a != null) a.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LOCKED);
Log.d("FRAGMENT_02","VISIBLE_HINT");
}
}
}
As you can see in our code, we use below to navigate between Fragments. (Below code shows navigating from first fragmnet to second)
FragmentManager fragmentManager=getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.setCustomAnimations(R.anim.from_right, R.anim.to_left);
transaction.replace(R.id.firstFragment, new SecondFragment1());
transaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
transaction.addToBackStack(null);
transaction.commit();
Looking at our code, and considering we have added the ViewPager as well, how can we make sure that onCreateView is only called once and setUserVisibleHint is called everytime the fragment is displayed?

there is challenges when using setUserVisibleHint is called.try viewPager.setOffscreenPageLimit(5); and use setMenuVisibility method and if you launch app on any fragment by notification
#Override
public void setMenuVisibility(boolean menuVisible) {
super.setMenuVisibility(menuVisible);
if(menuVisible && isResumed()){
// do your work here
}
if(!isResumed()){
// do your work when Activity is created
}
}

Put all of your code which you want should not be called everytime in onCreate() method and the code which you want should be called everytime in onCreateView() method.

Return to previously fragments

I am doing an Android app using fragments but i haven't previously experience with fragments.
I have a main FragmentActivity where i load a main view and i call my fragment class:
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_view);
FragmentTransaction FT = getFragmentManager().beginTransaction();
if (findViewById(R.id.fragmentAction) != null) {
FT.replace(R.id.fragmentAction, MainMenuFragment.newInstance(
getString(R.string.main_menu), getApplicationContext()));
}
FT.addToBackStack(null);
FT.commit();
}
#Override
public void onBackPressed() {
}
And this is my fragmet classm where when i push button call to other fragment:
public class MainMenuFragment extends Fragment {
private static String my_description = "";
private static Context my_context = null;
public static MainMenuFragment newInstance(String description,
Context context) {
my_description = description;
my_context = context;
MainMenuFragment f = new MainMenuFragment();
return f;
}
public MainMenuFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View view = null;
if (my_description.compareTo(getString(R.string.main_menu)) == 0) {
view = inflater.inflate(R.layout.main_menu, container, false);
}
return view;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
if (my_description.compareTo(getString(R.string.main_menu)) == 0) {
Button new_user = (Button) getView().findViewById(
R.id.button_newUser);
new_user.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
FragmentTransaction FT = getFragmentManager()
.beginTransaction();
FT.replace(R.id.fragmentAction, LdapFragment.newInstance(
getString(R.string.new_user), my_context));
FT.commit();
}
});
}
}
}
My question is: how can i do to return to previously fragment when i push back key? I add onBackPressed function in my FragmentActivity and capture the event, but what have i to do?

Use this code
#Override
public void onBackPressed() {
// TODO Auto-generated method stub
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
this.finish();
} else {
getSupportFragmentManager().popBackStack();
removeCurrentFragment();
}
}
public void removeCurrentFragment() {
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
Fragment currentFrag = getSupportFragmentManager().findFragmentById(
R.id.fragment_container);
setFragName("NONE");
if (currentFrag != null) {
setFragName(currentFrag.getClass().getSimpleName());
}
if (currentFrag != null) {
transaction.remove(currentFrag);
}
transaction.commit();
}

following is the code that i use. You need not do anything. Android system handles backpress and shows the appropriate fragment in the navigation order
#Override
public void onBackPressed() {
super.onBackPressed();
if (getFragmentManager().getBackStackEntryCount() == 0)
finish();
}
you missed the super.onBackPressed(); call. Try adding that to your code.

Just create method for add and back to fragment .
for example,
public void setFragment(Fragment fragment, boolean backStack, String tag) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
if (backStack) {
fragmentTransaction.addToBackStack(tag);
}
fragmentTransaction.replace(R.id.fragmentAction, MainMenuFragment.newInstance(
getString(R.string.main_menu), tag);
fragmentTransaction.commit();
}
call method from onCreate() or onResume()of your Activity.
setFragment(Your FragmentClass object, true, "tag");

SlidingMenu with ViewPager and ActionBarSherlock Tabs

In my calendar application, I am using ActionBarSherlock to display two tabs - 1) Calendar 2) Converter. On the click event of an ActionBar menu item, I'm using SlidingMenu drawer to display event summary for that month.
I want to use viewpager specifically for the Calendar tab and I have implemented it this way:
Main.java:
public class BaseActivity extends SlidingSherlockFragmentActivity
{
private ViewPager pager;
CalendarFragmentPagerAdapter mPagerAdapter;
private static final int MONTHS_LIMIT = 5;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle(R.string.app_name);
setContentView(R.layout.main);
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.main, new CalendarFragment())
.commit();
setBehindContentView(R.layout.content_frame);
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.content_frame, new EventsSummary())
.commit();
setSlidingActionBarEnabled(false);
final ActionBar bar = getSupportActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
bar.setHomeButtonEnabled(true);
ActionBar.Tab calendar = bar.newTab();
ActionBar.Tab converter = bar.newTab();
calendar.setText(this.getResources().getString(R.string.calendar));
converter.setText(this.getResources().getString(R.string.converter));
calendar.setTabListener(new MyTabListener());
converter.setTabListener(new MyTabListener());
bar.addTab(calendar);
bar.addTab(converter);
// customize the SlidingMenu
SlidingMenu sm = getSlidingMenu();
sm.setShadowWidthRes(R.dimen.shadow_width);
sm.setShadowDrawable(R.drawable.shadow);
sm.setBehindOffsetRes(R.dimen.actionbar_home_width);
sm.setSlidingEnabled(false);
mPagerAdapter = new CalendarFragmentPagerAdapter(getSupportFragmentManager());
pager = (ViewPager) this.findViewById(R.id.viewpager);
pager.setAdapter(mPagerAdapter);
pager.setCurrentItem(MONTHS_LIMIT / 2);
}
private class MyTabListener implements ActionBar.TabListener
{
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
if(tab.getPosition()==0)
{
CalendarFragment frag = new CalendarFragment();
ft.replace(R.id.main, frag);
}
else
{
ConverterFragment frag = new ConverterFragment();
ft.replace(R.id.main, frag);
}
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
}
public boolean onOptionsItemSelected(MenuItem item) {
Intent newActivity;
// Handle item selection
switch (item.getItemId()) {
case R.id.menu_slidingmenu:
toggle();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public class CalendarFragmentPagerAdapter extends FragmentPagerAdapter {
public CalendarFragmentPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
CalendarFragment fragment = new CalendarFragment();
Bundle args = new Bundle();
args.putInt("offset", position - MONTHS_LIMIT / 2);
fragment.setArguments(args);
return fragment;
}
#Override
public int getCount() {
return MONTHS_LIMIT;
}
}
}
CalendarFragment.java:
public class CalendarFragment extends Fragment
{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle args = getArguments();
int offset = args.getInt("offset"); //throws NullPointerException
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.simple_calendar_view, container, false);
.....
return v;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putBoolean("dummy", true);
}
}
The problem is at this line in the CalendarFragment:
int offset = args.getInt("offset");
It throws the error NullPointerException and debugging shows this is because Bundle args = getArguments() is null.
I tried to put the breakpoint at this line in the PagerAdapter:
Bundle args = new Bundle();
but it never reaches here and the application crashes throwing the NullPointerException.
Where am I going wrong?

Here
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.main, new CalendarFragment())
.commit();
and here
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
if (tab.getPosition() == 0) {
CalendarFragment frag = new CalendarFragment();
ft.replace(R.id.main, frag);
} else {
ConverterFragment frag = new ConverterFragment();
ft.replace(R.id.main, frag);
}
}
you're just creating an empty CalendarFragment instance without any arguments.
So your activity launches, creating an empty Fragment without arguments, and then crashes when trying to get those