I created a fragment with recyclerview and when I executed the application it doesn't load the data automatically for that I have to move to another view and then come back to this particular view to get the data loaded, I want when the application starts the list in recyclerview automatically retrieves the data from the firestore database.
If my code is required do let know.
Thank You for the assistance in advance.
HomeFragement Class
public class HomeFragment extends Fragment {
RelativeLayout mParent;
//FloatingActionButton addButton;
private static final String TAG = "DocSnippets";
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference PostsRef = db.collection("posts");
private CollectionReference likesRef;
private PostsAdapter adapter;
private FirestoreRecyclerOptions options;
private FirebaseAuth mAuth;
private String mUserId, id;
private Button commentsbutton;
RecyclerView recyclerView;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
//just change the fragment_dashboard
//with the fragment you want to inflate
//like if the class is HomeFragment it should have R.layout.home_fragment
//if it is DashboardFragment it should have R.layout.fragment_dashboard
mAuth = FirebaseAuth.getInstance();
mUserId = mAuth.getUid();
likesRef = db.collection("users").document(mUserId).collection("likes");
final View view = inflater.inflate(R.layout.fragment_home, container, false);
final FragmentActivity c = getActivity();
LinearLayoutManager layoutManager = new LinearLayoutManager(c);
Query query = PostsRef.orderBy("timestamp", Query.Direction.DESCENDING);
FirestoreRecyclerOptions<PostsModel> options = new FirestoreRecyclerOptions.Builder<PostsModel>()
.setQuery(query, PostsModel.class)
.build();
adapter = new PostsAdapter(options);
recyclerView = (RecyclerView) view.findViewById(R.id.recycler_view);
// recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(c));
recyclerView.setAdapter(adapter);
commentsbutton = (Button) view.findViewById(R.id.commenting_button);
mParent =view.findViewById(R.id.relative_home);
// return inflater.inflate(R.layout.fragment_home, null);
adapter.setOnItemClickListener(new PostsAdapter.OnItemClickListener() {
#Override
public void onItemClick(DocumentSnapshot documentSnapshot, int position) {
PostsModel note = documentSnapshot.toObject(PostsModel.class);
id = documentSnapshot.getId();
String path = documentSnapshot.getReference().getPath();
Log.d(TAG, "String post Id is: " + id);
Intent gotoClickPostDetailActivity = new Intent (view.getContext(), ClickPost.class);
gotoClickPostDetailActivity.putExtra("PostKey",id);
startActivity(gotoClickPostDetailActivity);
//
// Toast.makeText(c, "Position: " + position + " ID: " + id, Toast.LENGTH_SHORT).show();
//Toast.makeText(HomeFragment.this, "Position: " + position + " ID: " + id, Toast.LENGTH_SHORT).show();
}
});
return view;
}
private String getTime(long timestamp){
long ts = timestamp*1000;
SimpleDateFormat sdf = new SimpleDateFormat("hh:mm a");
String time = sdf.format(new Date(ts));
return time;
}
#Override
public void onStart() {
super.onStart();
adapter.startListening();
}
#Override
public void onStop() {
super.onStop();
adapter.stopListening();
}
}
MainActivity Class
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private FirebaseAuth mauth;
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference UsersRef = db.collection("Users");
private DocumentReference noteRef = db.document("Notebook/My First Note");
private MySharedPreferences sp;
String currentUserID;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
sp = MySharedPreferences.getInstance(this);
setContentView(R.layout.activity_main);
mauth = FirebaseAuth.getInstance();
// currentUserID = mauth.getCurrentUser().getUid();
UsersRef =FirebaseFirestore.getInstance().collection("Users");
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
Fragment fragment;
fragment = null;
switch (item.getItemId()) {
case R.id.navigation_home:
fragment = new HomeFragment();
break;
case R.id.navigation_dashboard:
fragment = new DashboardFragment();
break;
case R.id.navigation_notifications:
Intent intent = new Intent(MainActivity.this, AddPostActivity.class);
startActivity(intent);
// fragment = new NotificationsFragment();
break;
case R.id.navigation_post:
fragment = new ProfileFragment();
break;
case R.id.navigation_postlist:
fragment = new ProfileFragment();
break;
}
return loadFragment(fragment);
}
};
private boolean loadFragment(Fragment fragment) {
//switching fragment
if (fragment != null) {
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.fragment_container, fragment)
.commit();
return true;
}
return false;
}
#Override
protected void onStart()
{
super.onStart();
FirebaseUser currentUser = mauth.getCurrentUser();
if(currentUser == null)
{
SendUserToSignInActivity();
}
else
{
checkUserExistence();
}
}
}
your problem is in this line of code
Query query = PostsRef.orderBy("timestamp", Query.Direction.DESCENDING);
FirestoreRecyclerOptions<PostsModel> options = new
FirestoreRecyclerOptions.Builder<PostsModel>()
.setQuery(query, PostsModel.class)
.build();
adapter = new PostsAdapter(options);
PostsRef.orderBy take some time to get result from firebase but you can set result immediately which cause the problem
Related
When i'm switching from another fragment to home fragment, the fragment loads again the data to my recycler view. I want to save the recycler view state and restoring it when the user switch to my home fragment. My problem is that i don't know how to save a custom array list to onSaveInstanceState() and then retrieve this from the onCreateView() method.
My HomeFragment:
public class HomeFragment extends Fragment {
LoadingDialog progressDialog;
final DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
boolean isSearchOpen = false;
private EditText searchView;
ArrayList<PostModel> postModelArrayList;
RecyclerView recyclerView;
void loadPosts(View fragmentView, FirebaseUser user, ArrayList<PostModel> postModelArrayList, RecyclerView.Adapter postsAdapter, boolean isRefresh) {
rootRef.addListenerForSingleValueEvent(new ValueEventListener() {
#SuppressLint("NotifyDataSetChanged")
#Override
public void onDataChange(#NonNull #NotNull DataSnapshot snapshot) {
new Handler().postDelayed(() -> {
fragmentView.findViewById(R.id.constraintLayout2).setVisibility(View.GONE);
((HomeActivity)getContext()).findViewById(R.id.bottom_nav).setVisibility(View.VISIBLE);
}, 2000);
for (DataSnapshot snap : snapshot.child("posts").getChildren()) {
PostModel postModel = new PostModel();
postModel.setId(snap.child("id").getValue(String.class));
postModel.setImgUrl(snap.child("imgUrl").getValue(String.class));
postModel.setLikes(snap.child("likes").getValue(String.class));
postModel.setName(snap.child("name").getValue(String.class));
postModel.setProfileImgUrl(snap.child("authorProfilePictureURL").getValue(String.class));
postModel.setPostType(snap.child("postType").getValue(String.class));
// Show post in recycler adapter only if the user is not blocked
if (!snapshot.child("users").child(user.getUid()).child("blockedUsers").child(snap.child("name").getValue(String.class)).exists()) {
postModelArrayList.add(postModel);
}
}
if (snapshot.child("users").child(user.getUid()).child("blockedUsers").exists()) {
System.out.println(snapshot.child("users").child(user.getUid()).child("blockedUsers"));
}
postsAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull #NotNull DatabaseError error) {
Toast.makeText(getContext(), "Error: " + error, Toast.LENGTH_SHORT).show();
}
});
}
#Override
public void onSaveInstanceState(#NonNull Bundle outState) {
super.onSaveInstanceState(outState);
// i don't know what i need to do here
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_home, container, false);
TextView usernameLoadingScreen = view.findViewById(R.id.textView40);
ImageButton searchUserBtn = view.findViewById(R.id.searchPersonButton);
ImageButton notificationsBtn = view.findViewById(R.id.notificationsButton);
ImageButton searchUserButton = view.findViewById(R.id.enter_search_button);
View postsOfTheMonthBtn = view.findViewById(R.id.posts_of_the_month_btn);
searchView = view.findViewById(R.id.search_view);
DatabaseReference usersRef = FirebaseDatabase.getInstance().getReference("users");
FirebaseAuth auth = FirebaseAuth.getInstance();
FirebaseUser user = auth.getCurrentUser();
AdView mAdView = view.findViewById(R.id.adView);
AdRequest adRequest = new AdRequest.Builder().build();
recyclerView = view.findViewById(R.id.home_recycler_view);
postModelArrayList = new ArrayList<>();
final LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
final RecyclerView.Adapter recyclerAdapter = new PostRecyclerAdapter(postModelArrayList, getContext(), getActivity());
layoutManager.setReverseLayout(true);
layoutManager.setStackFromEnd(true);
recyclerView.setAdapter(recyclerAdapter);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(layoutManager);
progressDialog = LoadingDialog.Companion.get(getActivity());
searchView.setVisibility(View.GONE);
searchUserButton.setVisibility(View.GONE);
((HomeActivity)getContext()).findViewById(R.id.bottom_nav).setVisibility(View.GONE);
loadPosts(view, user, postModelArrayList, recyclerAdapter, false);
}
}
The problem I have been facing with the development is that there is a recyclerview inside my fragment which gets disappeared after I switch between two fragments on a particular activity. On the first time when the fragment loads everything works fine but afterwards I don't understand what goes wrong. I had tried to refer to various ways that people had posted over github like notifyDatasetChanged, etc. But nothing seems to work. I would appreciate if someone could help me out with this issue.
So here are my classes.
The ProfileFragment.java :
public class ProfileFragment extends Fragment {
FirebaseAuth firebaseAuth;
FirebaseUser user;
FirebaseDatabase firebaseDatabase;
DatabaseReference databaseReference;
StorageReference storageReference;
RecyclerView itemRecycler;
List<ModelProfile> modelProfiles;
AdapterProfile adapterProfile;
String storagePath= "Users_Profile_Cover_Image/-";
ImageView avatarIv,dp;
CardView card,cardArrow;
TextView nameTv, emailTv, phoneTv;
Button logout,update;
ExtendedFloatingActionButton fab;
ProgressDialog pd;
//..
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
final View view= inflater.inflate(R.layout.fragment_profile, container, false);
firebaseAuth = FirebaseAuth.getInstance();
user= firebaseAuth.getCurrentUser();
firebaseDatabase = FirebaseDatabase.getInstance();
databaseReference = firebaseDatabase.getReference("Users");
storageReference= getInstance().getReference();
loadItems();
return view;
}
private void loadItems() {
//Problem could be here
GridLayoutManager layoutManager= new GridLayoutManager(getContext(),3);
itemRecycler.setHasFixedSize(true);
itemRecycler.setLayoutManager(layoutManager);
itemRecycler.setVisibility(View.VISIBLE);
CollectionReference ref =FirebaseFirestore.getInstance().collection("All_Posts");
com.google.firebase.firestore.Query query = ref.whereEqualTo("uid",uid);
FirestoreRecyclerOptions<ModelProfile> options = new FirestoreRecyclerOptions.Builder<ModelProfile>()
.setQuery(query,ModelProfile.class).build();
adapterProfile = new AdapterProfile(options,getActivity());
itemRecycler.setAdapter(adapterProfile);
adapterProfile.startListening();
query.addSnapshotListener(new EventListener<QuerySnapshot>() {
#Override
public void onEvent(#Nullable QuerySnapshot value,
#Nullable FirebaseFirestoreException e) {
if (e != null) {
return;
}
assert value != null;
Log.i("Size",String.valueOf(value.getDocuments().size()));
if (value.getDocuments().size() > 0) { // List is populated
card.setVisibility(View.GONE);
cardArrow.setVisibility(View.GONE);
} else { // List is empty
card.setVisibility(View.VISIBLE);
cardArrow.setVisibility(View.VISIBLE);
}
}
});
}
//
// #Override
// public void onStart() {
// super.onStart();
// adapterProfile.startListening();
// }
//
//
//
// #Override
// public void onStop() {
// super.onStop();
// adapterProfile.stopListening();
// }
#Override
public void onResume() {
super.onResume();
adapterProfile.startListening();
}
}
Adapter:-
public class AdapterProfile extends FirestoreRecyclerAdapter<ModelProfile,AdapterProfile.MyHolder> {
Context context;
public String im;
public AdapterProfile(#NonNull FirestoreRecyclerOptions<ModelProfile> options, Activity Context) {
super(options);
context = Context;
}
#Override
protected void onBindViewHolder(#NonNull MyHolder holder, int position, #NonNull ModelProfile model) {
String uid = model.getUid();
String uEmail =model.getuEmail();
}
#NonNull
#Override
public MyHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
//..
}
class MyHolder extends RecyclerView.ViewHolder{
//..
}
Activity on which Fragment switching takes place
public class LandingActivity extends AppCompatActivity {
FirebaseAuth firebaseAuth;
DatabaseReference userDbRef;
FirebaseUser user;
String uid,dp;
ChipNavigationBar chipNavigationBar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_landing);
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new InventoryFragment()).commit();
bottomMenu();
}
private void bottomMenu() {
chipNavigationBar.setOnItemSelectedListener(new ChipNavigationBar.OnItemSelectedListener() {
//problem could be here as well.........
#Override
public void onItemSelected(int i) {
Fragment fragment=null;
switch(i) {
case R.id.bottom_nav_2:
fragment = new CltFragment();
break;
case R.id.bottom_nav_3:
fragment = new MaceFragment();
break;
case R.id.bottom_nav_profile:
fragment = new ProfileFragment();
break;
}
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,fragment).commit();
}
});
}
private void checkUserStatus()
{
FirebaseUser user= firebaseAuth.getCurrentUser();
if(user !=null)
{
uid=user.getUid();
}
else
{
startActivity(new Intent(LandingActivity.this,MainActivity.class));
finish();
}
}
#Override
public void onResume() {
//Problem could be here
super.onResume();
Intent intent = getIntent();
String frag = "";
if(intent.hasExtra("frag")) {
frag = intent.getExtras().getString("frag");
}
else
{
//..
}
switch(frag)
{
//..
case "ProfileFragment":
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new ProfileFragment()).commit();
chipNavigationBar.setItemSelected(R.id.bottom_nav_profile,true);
break;
}
}
}
Thanks for having looked at my Problem!
Try using this
getSupportFragmentManager().beginTransaction().add(R.id.fragment_container,new InventoryFragment()).commit();
Instead of this
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new InventoryFragment()).commit();
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 3 years ago.
In my app, i have an activity that have recyclerview inside a fragment and the recycleview retrieve data from cloud store Firebase. I want to open new activity that will retrieve the data according to the link(that display on the recycler view) user has clicked.
How do i get the data and display it in new activity?
From ForumTitle.java > Show ReviewFragment.java > User click a value > Show ForumInterface.java
ForumTitle.java
public class ForumTitle extends AppCompatActivity {
private FirebaseFirestore db = FirebaseFirestore.getInstance();
ImageButton IVReview,IVTechnical,IVHardware;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_forum_title);
View.OnClickListener listener = new View.OnClickListener() {
#Override
public void onClick(View v) {
Fragment selectedFragment = null;
if (v == findViewById(R.id.iBReview)){
selectedFragment = new ReviewFragment();
}
else if (v == findViewById(R.id.iBTech)){
selectedFragment = new TechnicalSupportFragment();
}
else if (v == findViewById(R.id.iBHardware)){
selectedFragment = new HardwareFragment();
}
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.fragment_container,selectedFragment);
transaction.commit();
}
};
IVReview = (ImageButton)findViewById(R.id.iBReview);
IVTechnical = (ImageButton)findViewById(R.id.iBTech);
IVHardware = (ImageButton)findViewById(R.id.iBHardware);
IVReview.setOnClickListener(listener);
IVTechnical.setOnClickListener(listener);
IVHardware.setOnClickListener(listener);
}
}
ReviewFragment.java
public class ReviewFragment extends Fragment {
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference userRef = db.collection("Review");
private ForumAdapter adapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_review,container,false);
return view;
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
Query query = userRef.orderBy("DatePosted",Query.Direction.DESCENDING);
FirestoreRecyclerOptions<Forum> options = new
FirestoreRecyclerOptions.Builder<Forum>()
.setQuery(query,Forum.class)
.build();
adapter = new ForumAdapter(options);
RecyclerView recyclerView = (RecyclerView)view.findViewById(R.id.rvReview);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this.getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.setAdapter(adapter);
adapter.setOnItemClickListener(new ForumAdapter.OnItemClickListener() {
#Override
public void onItemClick(DocumentSnapshot documentSnapshot, int position) {
Forum forum = documentSnapshot.toObject(Forum.class);
String title = forum.getTitle();
String id = documentSnapshot.getId();
Intent intent = new Intent(getActivity(), ForumInterface.class);
Bundle extras = intent.getExtras();
extras.putString("FORUM_TYPE","Review");
extras.putString("FORUM_ID",id);
extras.putString("TITLE",title);
startActivity(intent);
}
});
}
#Override
public void onStart() {
super.onStart();
adapter.startListening();
}
#Override
public void onStop() {
super.onStop();
adapter.stopListening();
}
ForumInterface.java
public class ForumInterface extends AppCompatActivity {
private FirebaseFirestore db = FirebaseFirestore.getInstance();
Intent intent = getIntent();
Bundle extras = intent.getExtras();
String forum_title = extras.getString("TITLE");
String forum_type = extras.getString("FORUM_TYPE");
String forum_id = extras.getString("FORUM_ID");
private CollectionReference userRef = db.collection(forum_type).document(forum_id).collection(forum_title);
private ForumAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_forum_interface);
TextView test = (TextView)findViewById(R.id.tvForumTitle);
test.setText(forum_title);
}
}
ForumAdapter.java
public class ForumAdapter extends FirestoreRecyclerAdapter<Forum,ForumAdapter.ForumHolder> {
private OnItemClickListener listener;
public ForumAdapter(FirestoreRecyclerOptions<Forum> options) {
super(options);
}
#Override
public void onBindViewHolder(ForumHolder forumHolder, int i, Forum forum) {
forumHolder.textViewTitle.setText(forum.getTitle());
forumHolder.textViewDescription.setText(forum.getDescription());
forumHolder.timeStamp.setText(forum.getDatePosted().toString());
}
#NonNull
#Override
public ForumHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
android.view.View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardviewforumtitle,parent,false);
return new ForumHolder(v);
}
class ForumHolder extends RecyclerView.ViewHolder{
TextView textViewTitle;
TextView textViewDescription;
TextView timeStamp;
public ForumHolder(View itemView) {
super(itemView);
textViewTitle = itemView.findViewById(R.id.title);
textViewDescription = itemView.findViewById(R.id.description);
timeStamp = itemView.findViewById(R.id.timestamp);
textViewTitle.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
int position = getAdapterPosition();
// NO_POSITION to prevent app crash when click -1 index
if(position != RecyclerView.NO_POSITION && listener !=null ){
listener.onItemClick(getSnapshots().getSnapshot(position),position);
}
}
});
}
}
public interface OnItemClickListener{
void onItemClick(DocumentSnapshot documentSnapshot, int position);
}
public void setOnItemClickListener(OnItemClickListener listener){
this.listener = listener;
}
#Override
public int getItemCount() {
return super.getItemCount();
}
}
With the code above i run it, i got an error
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.os.Bundle.putString(java.lang.String, java.lang.String)' on a null object reference
at my.edu.fsktm.um.finalproject.Fragment.ReviewFragment$1.onItemClick(ReviewFragment.java:61)
at my.edu.fsktm.um.finalproject.ForumTitle.ForumAdapter$ForumHolder$1.onClick(ForumAdapter.java:56)
The picture of my app
When I clicked the title "GTX 1660 Ti Gaming X"
You try to set content on a Bundle which is null in your ReviewFragment's onClick. Use new Bundle() instead of intent.getExtras(); to instantiate Bundle
Bundle extras = new Bundle();
extras.putString("FORUM_TYPE","Review");
extras.putString("FORUM_ID",id);
extras.putString("TITLE",title);
//You have to set the bundle to intent
intent.putExtras(extras);
startActivity(intent);
Beside this move below code inside onCreate of ForumInterface Activity
Intent intent = getIntent();
Bundle extras = intent.getExtras();
String forum_title = extras.getString("TITLE");
String forum_type = extras.getString("FORUM_TYPE");
String forum_id = extras.getString("FORUM_ID");
And here is the complete Activity.
public class ForumInterface extends AppCompatActivity {
private FirebaseFirestore db;
private CollectionReference userRef;
private ForumAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_forum_interface);
Intent intent = getIntent();
Bundle extras = intent.getExtras();
String forum_title = extras.getString("TITLE");
String forum_type = extras.getString("FORUM_TYPE");
String forum_id = extras.getString("FORUM_ID");
db = FirebaseFirestore.getInstance();
userRef = db.collection(forum_type).document(forum_id).collection(forum_title);
TextView test = (TextView)findViewById(R.id.tvForumTitle);
test.setText(forum_title);
}
}
I'm using the firebaseRecyclerAdaper on a fragment and i want to open an item from de populated list from firebase and send the data to a new fragment. Can u guys tell me please how can i start the FragmentDetail from the onCLickListener on FragmentAllPosts and pass the PostModel parameter to it?
Main Activity:
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private static final String TAG = "TAG" ;
private FirebaseAuth firebaseAuth;
private DatabaseReference databaseReference , postsRef;
private StorageReference profileImgRef;
private CircleImageView circleImageViewMain;
private TextView nameEdtTxt, emailEdtTxt;
Fragment fragment= null;
private RecyclerView recyclerView;
private FloatingActionButton fab;
private ProgressDialog progressDialog;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
progressDialog= new ProgressDialog(this);
progressDialog.setMessage("Please wait!");
progressDialog.setCanceledOnTouchOutside(false);
//Initialize Firebase modules
firebaseAuth=FirebaseAuth.getInstance();
databaseReference= FirebaseDatabase.getInstance().getReference().child("users");
postsRef= FirebaseDatabase.getInstance().getReference().child("posts");
profileImgRef= FirebaseStorage.getInstance().getReference();
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.addDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
View header = navigationView.getHeaderView(0);
circleImageViewMain = (CircleImageView) header.findViewById(R.id.circleImageHeader);
nameEdtTxt = (TextView) header.findViewById(R.id.txtName);
emailEdtTxt =(TextView)header.findViewById(R.id.txtEmail);
if (firebaseAuth.getCurrentUser()!=null){
LoadUserData(CheckUserDataBase());
}
ViewPager vp_pages= (ViewPager) findViewById(R.id.vp_pages);
PagerAdapter pagerAdapter=new FragmentAdapter(getSupportFragmentManager());
vp_pages.setAdapter(pagerAdapter);
TabLayout tbl_pages= (TabLayout) findViewById(R.id.tabs);
tbl_pages.setupWithViewPager(vp_pages);
tbl_pages.setTabTextColors(ColorStateList.valueOf(Color.parseColor("#FFFFFF")));
tbl_pages.setHorizontalScrollBarEnabled(true);
fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
fragment= new AddPostFrag();
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction= fragmentManager.beginTransaction();
transaction.add(R.id.add_post_container, fragment).commit();
fab.hide();
}
});
}
class FragmentAdapter extends FragmentPagerAdapter {
public FragmentAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position){
case 0:
return new FragmentAllPosts();
case 1:
return new FragmentLosts();
case 2:
return new FragmentFounds();
}
return null;
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position){
//
//Your tab titles
//
case 0:return "All";
case 1:return "Losts";
case 2: return "Founds";
default:return null;
}
}
}
#Override
protected void onStart() {
super.onStart();
FirebaseUser user= firebaseAuth.getCurrentUser();
if (user == null){
SendUserToLogin();
} else {
CheckUserDataBase();
}
}
public static class PostsViewHolder extends RecyclerView.ViewHolder {
CircleImageView circleImageView;
ImageView imageView;
TextView authorNdate, location, description;
public PostsViewHolder(#NonNull View itemView) {
super(itemView);
circleImageView= itemView.findViewById(R.id.circleImageView_cv);
imageView= itemView.findViewById(R.id.imageView_cv);
authorNdate= itemView.findViewById(R.id.author_date_cv);
location = itemView.findViewById(R.id.location_cv);
description = itemView.findViewById(R.id.description_cv);
}
}
private void UpdateHome() {
}
private void LoadUserData(final String uid) {
try {
final File localFile =File.createTempFile("profile","png");
StorageReference filepath=profileImgRef.child(uid).child("profileImg/profile.png");
filepath.getFile(localFile)
.addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
#Override
public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
Picasso.get()
.load(localFile)
.placeholder(R.drawable.ic_account)
.into(circleImageViewMain);
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(MainActivity.this,
"Profile photo not found, please update your profile!",
Toast.LENGTH_SHORT).show();
SendUserToSetup();
}
});
} catch (IOException e) {
e.printStackTrace();
}
databaseReference.child(uid).child("userInfo").addValueEventListener(
new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.hasChild("name")){
String name = dataSnapshot.child("name").getValue().toString();
nameEdtTxt.setText(name);
String email = dataSnapshot.child("email").getValue().toString();
emailEdtTxt.setText(email);
} else {
Toast.makeText(MainActivity.this,
"Profile name does not exists, please update your profile",
Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
}
);
}
#Override
protected void onStop() {
super.onStop();
}
private String CheckUserDataBase() {
final String userID =firebaseAuth.getCurrentUser().getUid();
databaseReference.addValueEventListener(
new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (!dataSnapshot.child(userID).hasChild("userInfo")){
SendUserToSetup();
} else {
UpdateHome();
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
}
);
return userID;
}
private void SendUserToSetup() {
Intent i = new Intent(this,SetupActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK|Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(i);
}
private void SendUserToLogin() {
Intent i = new Intent(this,LoginActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK|Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(i);
}
#Override
public void onBackPressed() {
DrawerLayout drawer = findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (getSupportFragmentManager().getBackStackEntryCount() >0)
{
getSupportFragmentManager().beginTransaction().remove(fragment).commit();
} else
{
super.onBackPressed();
}
fab.show();
}
#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) {
// 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.
int id = item.getItemId();
switch (id){
case R.id.nav_home:
super.onResume();
if (fragment!=null){
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction transaction= fragmentManager.beginTransaction();
transaction.remove(fragment).commit();
fab.show();
}
break;
case R.id.nav_profile:
super.onPause();
break;
case R.id.nav_my_posts:
super.onPause();
break;
case R.id.nav_messeges:
super.onPause();
break;
case R.id.nav_settings:
super.onPause();
break;
case R.id.nav_logout:
SendUserToLogin();
firebaseAuth.signOut();
break;
}
DrawerLayout drawer = findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
Fragment with the FirebaseRecyclerAdapter
public class FragmentAllPosts extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
private DatabaseReference postsRef;
private Context context= getContext();
Fragment mFragment;
Bundle mBundle;
public FragmentAllPosts() {
// Required empty public constructor
}
public static FragmentAllPosts newInstance(String param1, String param2) {
FragmentAllPosts fragment = new FragmentAllPosts();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
private RecyclerView recyclerAllPosts;
private ProgressDialog progressDialog;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
progressDialog= new ProgressDialog(getActivity());
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_all_posts,container,false);
postsRef= FirebaseDatabase.getInstance().getReference().child("posts");
recyclerAllPosts= v.findViewById(R.id.recycler_all_posts);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
linearLayoutManager.setReverseLayout(true);
linearLayoutManager.setStackFromEnd(true);
recyclerAllPosts.setLayoutManager(linearLayoutManager);
return v;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
this.context=context;
}
#Override
public void onStart() {
super.onStart();
progressDialog.show();
FirebaseRecyclerOptions<PostsModel> options=
new FirebaseRecyclerOptions.Builder<PostsModel>()
.setQuery(postsRef,PostsModel.class)
.setLifecycleOwner(this)
.build();
FirebaseRecyclerAdapter<PostsModel,PostsViewHolder> adapter=
new FirebaseRecyclerAdapter<PostsModel, PostsViewHolder>(options) {
#Override
protected void onBindViewHolder(#NonNull final PostsViewHolder holder, int position, #NonNull final PostsModel model) {
String processedTime= CalculateTime(model.getData());
Picasso.get().load(Uri.parse(model.getUserImg())).into(holder.circleImageView);
Picasso.get().load(Uri.parse(model.getImageUri())).into(holder.imageView);
holder.authorNdate.setText(model.getAuthor()+" updated "+processedTime);
holder.location.setText(model.getLocation());
holder.description.setText(model.getDescription());
holder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Fragment frag= new FragmentDetail();
getFragmentManager().beginTransaction().replace(R.id.add_post_container,frag)
.addToBackStack(null).commit();
}
});
}
#NonNull
#Override
public PostsViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view= LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.card_view,viewGroup,false );
PostsViewHolder viewHolder= new PostsViewHolder(view);
return viewHolder;
}
};
recyclerAllPosts.setAdapter(adapter);
progressDialog.dismiss();
adapter.startListening();
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
public String CalculateTime(String inputTime){
String timeOut;
Calendar currentTime= Calendar.getInstance();
SimpleDateFormat dateFormat= new SimpleDateFormat(getString(R.string.date_format));
dateFormat.format(currentTime.getTime());
SimpleDateFormat postFormat= new SimpleDateFormat(getString(R.string.date_format));
Calendar postTime = Calendar.getInstance();
try {
Date datePost=postFormat.parse(inputTime);
postTime.setTime(datePost);
} catch (ParseException e) {
e.printStackTrace();
}
long timeCurrent= currentTime.getTimeInMillis();
long timePost = postTime.getTimeInMillis();
long diff= timeCurrent- timePost;
long minutes= diff/(60*1000);
long hours = diff/(60 * 60 * 1000);
long days = diff/(24 * 60 * 60 * 1000);
if (minutes<59 && minutes>1){
timeOut=Long.toString(minutes)+" mins ago";
} else if (minutes<1){
timeOut=" just now";
}else if (hours<24 && minutes>59){
timeOut=Long.toString(hours)+" hour(s) ago";
}else {
timeOut=Long.toString(days)+" day(s) ago";
}
return timeOut;
}
static class PostsViewHolder extends RecyclerView.ViewHolder {
CircleImageView circleImageView;
ImageView imageView;
TextView authorNdate, location, description;
public PostsViewHolder(#NonNull View itemView) {
super(itemView);
itemView.setTag(this);
circleImageView= itemView.findViewById(R.id.circleImageView_cv);
imageView= itemView.findViewById(R.id.imageView_cv);
authorNdate= itemView.findViewById(R.id.author_date_cv);
location = itemView.findViewById(R.id.location_cv);
description = itemView.findViewById(R.id.description_cv);
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
Detail Fragment:
public class FragmentDetail extends Fragment {
public FragmentDetail() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_detail, container, false);
}
}
I'd suggest a read on the documentation. Passing data between two activities should be done via interfaces.
As suggested by the official site
I am trying to refresh a RecyclerView by assigning a new adapter to the RecyclerView but it is throwing a NullPointerException.
I have created a TabLayout which has three tabs and when you reselect the first tab the method is called to refresh the RecyclerView. But, I am getting a NullPointerException on recyclerViewAdapter.notifyDataSetChanged();. I have initialized recyclerViewAdapter in the onCreateView(); but I still get an Exception.
EDIT :
This is a fragment not an Activity, I cannot setContentView();. Please read the question before down voting or doing anything not helpful.
Please suggest a proper way if I am doing it wrong.
Fragment which has the RecyclerView :
Tab1.class :
public class Tab1 extends Fragment {
private RecyclerView recyclerView;
private RecyclerViewAdapter recyclerViewAdapter;
private List<World> worldList;
private OnFragmentInteractionListener mListener;
private DBHelper helper;
private Context myContext;
private View view;
#Override
public void onStart() {
this.helper = new DBHelper(getContext());
recyclerViewAdapter = new RecyclerViewAdapter(getContext(), helper.getList());
super.onStart();
}
public Tab1() {
}
public void update() {
recyclerViewAdapter.notifyDataSetChanged();
}
#Override
public void onCreate(Bundle savedInstanceState) {
this.helper = new DBHelper(getContext());
this.worldList = new ArrayList<>();
this.worldList = helper.getList();
this.recyclerViewAdapter = new RecyclerViewAdapter(getContext(), this.worldList);
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_tab1, container, false);
recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
recyclerViewAdapter = new RecyclerViewAdapter(getContext(), worldList);
recyclerView.setAdapter(recyclerViewAdapter);
return view;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
void onFragmentInteraction(Uri uri);
}
}
The method is called from the MainActivity.class(When the Tab is re selected).
MainActivty.class :
public class MainActivity extends AppCompatActivity implements Tab1.OnFragmentInteractionListener, Tab2.OnFragmentInteractionListener, Tab3.OnFragmentInteractionListener {
DBHelper helper;
World world;
Location location;
GPSTracker tracker;
RecyclerViewAdapter adapter;
public static Context CONTEXT = null;
RecyclerView recyclerView;
public Tab1 tab1;
public static final String BROADCAST_ACTION = "e.wolverine2.thewalkingapp";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 123);
CONTEXT = getApplicationContext();
MessageReciever reciever = new MessageReciever(new Message());
Intent intent = new Intent(this, MyService.class);
intent.putExtra("reciever", reciever);
startService(intent);
tracker = new GPSTracker(getApplicationContext());
location = tracker.getLocation();
helper = new DBHelper(getApplicationContext());
tab1 = new Tab1();
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
adapter = new RecyclerViewAdapter(getApplicationContext(), helper.getList());
final TabLayout tabLayout = (TabLayout) findViewById(R.id.myTabLayout);
tabLayout.addTab(tabLayout.newTab().setText("LOCATIONS"));
tabLayout.addTab(tabLayout.newTab().setText("TOTAL DISTANCE"));
tabLayout.addTab(tabLayout.newTab().setText("CALS"));
tabLayout.getTabAt(0).setIcon(R.drawable.ic_list);
tabLayout.getTabAt(1).setIcon(R.drawable.ic_person_pin);
tabLayout.getTabAt(2).setIcon(R.drawable.ic_fitness_excercise);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
//onError();
final ViewPager viewPager = (ViewPager) findViewById(R.id.myViewPager);
final PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(pagerAdapter);
viewPager.setOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
if (tab.getPosition() == 0) {
Tab1 tab1 = new Tab1();
tab1.update();
}
}
});
}
public void locationChanged(double longi, double lati) {
final Location location = new Location("");
location.setLatitude(lati);
location.setLongitude(longi);
world = new World();
String timeStamp = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss").format(new Date());
world.setLongitude(location.getLongitude());
world.setLatitiude(location.getLatitude());
world.setDate(timeStamp);
world.setTime(timeStamp);
world.setLocation("Anonymous");
helper.addRow(world);
//tab1.update(getApplicationContext());
}
#Override
public void onFragmentInteraction(Uri uri) {
}
public class Message {
public void displayMessage(int resultCode, Bundle resultData) throws NullPointerException {
double longi = resultData.getDouble("longitude");
double lati = resultData.getDouble("latitude");
locationChanged(longi, lati);
//Toast.makeText(MainActivity.this, "TOASTY X : " + e.getMessage(), Toast.LENGTH_SHORT).show();
//Log.v("TOASTY X : ","" + e.getMessage());
}
}
public void onError() {
helper.onDropTable();
Toast.makeText(this, "TABLE DROPED!", Toast.LENGTH_SHORT).show();
}
}
Logcat :
java.lang.NullPointerException: Attempt to invoke virtual method 'void e.wolverine2.thewalkingapp.RecyclerViewAdapter.notifyDataSetChanged()' on a null object reference
at e.wolverine2.thewalkingapp.Tab1.update(Tab1.java:57)
at e.wolverine2.thewalkingapp.MainActivity$1.onTabReselected(MainActivity.java:101)
at android.support.design.widget.TabLayout.dispatchTabReselected(TabLayout.java:1177)
at android.support.design.widget.TabLayout.selectTab(TabLayout.java:1136)
at android.support.design.widget.TabLayout.selectTab(TabLayout.java:1128)
at android.support.design.widget.TabLayout$Tab.select(TabLayout.java:1427)
at android.support.design.widget.TabLayout$TabView.performClick(TabLayout.java:1537)
at android.view.View$PerformClick.run(View.java:23985)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6816)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1563)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1451)
Java Tip: When it gets here:
Tab1 tab1 = new Tab1();
tab1.update();
A new Tab is instantiated using the cunstructor:
public Tab1() {
}
in your Tab class. as you see the recyclerView is not initialized up to this point.So the recyclerView is actually Null!
Answer: To correctly implement fragment take a look at this:
https://stackoverflow.com/a/5161143/6094503
What you looking for is the following lines:
Fragment newFragment = new DebugExampleTwoFragment();
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(CONTENT_VIEW_ID, newFragment).commit();
but I think you need more study about fragments and how they're added to (or removed from) an activity