I am using firebase database where I am saving data manually and retrieving data in the app and that is working well but I want that when user clicks the listview item that must open another activity and within that must retrieve another table.
Here is below my code
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private ProgressDialog progressDialog;
DatabaseReference mref =
FirebaseDatabase.getInstance().getReference("users");
ListView mlistview;
ArrayList<String> arrayList=new ArrayList<>();
ArrayAdapter<String> arrayAdapter;
private BottomNavigationView.OnNavigationItemSelectedListener
mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
progressDialog.show();
startActivity(new
Intent(profilemain.this,profilemain.class));
return true;
case R.id.navigation_dashboard:
Toast.makeText(profilemain.this,"hi
hello",Toast.LENGTH_SHORT).show();
return true;
case R.id.navigation_notifications:
Toast.makeText(profilemain.this,"hi
hello",Toast.LENGTH_SHORT).show();
return true;
case R.id.navigation_signout:
Toast.makeText(profilemain.this,"You have successfully
Signed out",Toast.LENGTH_SHORT).show();
mAuth.signOut();
return true;
}
return false;
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profilemain);
progressDialog.setMessage("loading");
progressDialog.setTitle("database is");
mlistview=(ListView) findViewById(R.id.listview);
Firebase.setAndroidContext(this);
DatabaseReference ref = FirebaseDatabase.getInstance()
.getReference("users");
//mref=new Firebase("https://stark-1dffd.firebaseio.com/users");
arrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,arrayList);
mlistview.setAdapter(arrayAdapter);
mref.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
String value= dataSnapshot.getValue(String.class);
arrayList.add(value);
arrayAdapter.notifyDataSetChanged();
//
//
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
mAuth = FirebaseAuth.getInstance();
mAuthListener = new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser()==null){
startActivity(new
Intent(profilemain.this,MainActivity.class));
}
}
};
}
#Override
protected void onStart() {
super.onStart();
mAuth.addAuthStateListener(mAuthListener);
}
add an ItemClickListener on your ListView
mlistview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent in = new Intent(MyActivity.this, DetailActivity.class);
in.putExtra("data", arrayList.get(position);// add the selected String from the ListView
startActivity(in);
}
});
and read the data from the other activity:
String data = getIntent().getStringExtra("data");
Related
I am trying to work with ChildEventListener in Firebase to populate the listView with the "title" field of every child nodes. But it's not working properly. My first activity is AuthActivity, which contains googleSignIn Button, by which the user can log in or authenticate. After that, in MainActivity a listView supposes to populate with the data using ChildEventListener datasnapshot. But it remains blank.
The interesting part is, If I go back to the AuthActivity with the back button pressed and again click the login button, it agains taking me to the MainActivity and somehow this time it's shows the listView with the correct data. And after closing the app, the same error happens. I am not getting any errors in the Logcat.
Here is my AuthActivity File
public class AuthActivity extends AppCompatActivity {
public static final int RC_SIGN_IN = 100;
SignInButton signInButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_auth);
signInButton = findViewById(R.id.signInButton);
signInButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// Choose authentication providers
List<AuthUI.IdpConfig> providers = Arrays.asList(
new AuthUI.IdpConfig.GoogleBuilder().build());
// Create and launch sign-in intent
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setAvailableProviders(providers)
.build(),
RC_SIGN_IN);
}
});
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RC_SIGN_IN) {
IdpResponse response = IdpResponse.fromResultIntent(data);
if (resultCode == RESULT_OK) {
Intent intent = new Intent(AuthActivity.this, MainActivity.class);
startActivity(intent);
} else {
Toast.makeText(this, "Login Failed! Please try again.", Toast.LENGTH_LONG).show();
}
}
}
}
And The MainActivity File
public class MainActivity extends AppCompatActivity {
public static final int RC_SIGN_IN = 100;
ListView listView;
ArrayList<String> titlesArray;
FirebaseDatabase database;
DatabaseReference databaseReference;
FirebaseUser user;
ChildEventListener childEventListener;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = findViewById(R.id.listView);
titlesArray = new ArrayList();
//Get the associated login user info
user = FirebaseAuth.getInstance().getCurrentUser();
//Write a message to the database
database = FirebaseDatabase.getInstance();
databaseReference = database.getReference().child("notes").child(user.getUid());
//Adding adapter to the list of titles
ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, titlesArray);
listView.setAdapter(adapter);
childEventListener = new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Note notes = dataSnapshot.getValue(Note.class);
titlesArray.add(notes.getTitle());
}
#Override
public void onChildChanged(#NonNull DataSnapshot dataSnapshot, #Nullable String s) {
}
#Override
public void onChildRemoved(#NonNull DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(#NonNull DataSnapshot dataSnapshot, #Nullable String s) {
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(MainActivity.this, "Loading failed!", Toast.LENGTH_SHORT).show();
}
};
databaseReference.addChildEventListener(childEventListener);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.sign_out_menu:
AuthUI.getInstance()
.signOut(this);
return true;
case R.id.add_new:
Intent intent = new Intent(MainActivity.this, AddActivity.class);
startActivity(intent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
It is because you are not notifying adapter after getting data from firebase callback.
Just replace your listener like below.
childEventListener = new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Note notes = dataSnapshot.getValue(Note.class);
titlesArray.add(notes.getTitle());
adapter.notifyDataSetChanged();
}
#Override
public void onChildChanged(#NonNull DataSnapshot dataSnapshot, #Nullable String s) {
}
#Override
public void onChildRemoved(#NonNull DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(#NonNull DataSnapshot dataSnapshot, #Nullable String s) {
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(MainActivity.this, "Loading failed!", Toast.LENGTH_SHORT).show();
}
};
i want the Activity must show Progress Dialog while fetching data from Firebase database.it is not showing anything and gets crashed. here is my code below
public class profilemain extends AppCompatActivity {
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private ProgressDialog progressDialog;
DatabaseReference mref =
FirebaseDatabase.getInstance().getReference("users");
ListView mlistview;
ArrayList<String> arrayList=new ArrayList<>();
ArrayAdapter<String> arrayAdapter;
private BottomNavigationView.OnNavigationItemSelectedListener
mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
progressDialog.show();
startActivity(new
Intent(profilemain.this,profilemain.class));
return true;
case R.id.navigation_dashboard:
Toast.makeText(profilemain.this,"hi
hello",Toast.LENGTH_SHORT).show();
return true;
case R.id.navigation_notifications:
Toast.makeText(profilemain.this,"hi
hello",Toast.LENGTH_SHORT).show();
return true;
case R.id.navigation_signout:
Toast.makeText(profilemain.this,"You have successfully
Signed out",Toast.LENGTH_SHORT).show();
mAuth.signOut();
return true;
}
return false;
}
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profilemain);
progressDialog.setMessage("loading");
progressDialog.setTitle("database is");
mlistview=(ListView) findViewById(R.id.listview);
Firebase.setAndroidContext(this);
DatabaseReference ref = FirebaseDatabase.getInstance()
.getReference("users");
//mref=new Firebase("https://stark-1dffd.firebaseio.com/users");
arrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,arrayList);
mlistview.setAdapter(arrayAdapter);
mref.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
String value= dataSnapshot.getValue(String.class);
arrayList.add(value);
arrayAdapter.notifyDataSetChanged();
//
//
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
mAuth = FirebaseAuth.getInstance();
mAuthListener = new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser()==null){
startActivity(new
Intent(profilemain.this,MainActivity.class));
}
}
};
}
#Override
protected void onStart() {
super.onStart();
mAuth.addAuthStateListener(mAuthListener);
}
Process: com.food.sheenishere.stark, PID: 16408
com.google.firebase.database.DatabaseException: Failed to convert value of type
java.util.HashMap to String
at com.google.android.gms.internal.zg.zzb(Unknown Source)
at com.google.android.gms.internal.zg.zza(Unknown Source)
at com.google.firebase.database.DataSnapshot.getValue(Unknown Source)
at com.food.sheenishere.stark.home$1.onChildAdded(home.java:49)
at com.google.android.gms.internal.px.zza(Unknown Source)
at com.google.android.gms.internal.vj.zzHX(Unknown Source)
at com.google.android.gms.internal.vp.run(Unknown Source)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
07-15 20:49:51.645 16408-16435/com.food.sheenishere.stark W/DynamiteModule:
Local module descriptor class for com.google.firebase.auth not found.
The problem in your code is that your are trying to use show(), setMessage("loading") and setTitle("database is") methods on a ProgressDialog object that have never been initialized.
In order to solve your problem you need to use the code below:
ProgressDialog progressDialog = new ProgressDialog(this);
It will solve your problem for sure.
Your should initialize progress dialog.. bellow like
private ProgressDialog pDialog;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
pDialog = new ProgressDialog(profilemain.this);
pDialog.setMessage("loading..");
}
I have an activity for searching in firebase, it contains edittext for typing the text and button when I press the button The results supposed to appear in the recyclerview but when I press the button the first time nothing appears unless I press the button for the second time
the code of findDataActivity
public class FindDataActivity extends AppCompatActivity {
DatabaseReference db;
FirebaseHelper helper;
MyAdapter adapter;
RecyclerView rv;
EditText findETxt;
Button findBtn;
ArrayList<Paints> p;
String s;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_find_data);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
ActionBar actionBar = getSupportActionBar();
if(actionBar != null)
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
//SETUP RECYCLER
rv = (RecyclerView) findViewById(R.id.rvsearch);
rv.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
//INITIALIZE FIREBASE DB
db = FirebaseDatabase.getInstance().getReference("Database");
adapter = new MyAdapter(FindDataActivity.this, p);
rv.setAdapter(adapter);
findBtn = (Button) findViewById(R.id.find_btn);
helper = new FirebaseHelper(db);
}
public void search(View view) {
db.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
findETxt = (EditText) findViewById(R.id.findETxt);
s = findETxt.getText().toString();
p=helper.retrieveSearch(s);
adapter = new MyAdapter(FindDataActivity.this, p);
rv.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id=item.getItemId();
if(id == android.R.id.home){
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
}
the code of firebase
public class FirebaseHelper {
DatabaseReference db;
Boolean saved=null;
Boolean saved1=null;
ArrayList<Paints> paints=new ArrayList<>();
ArrayList<String> keys=new ArrayList<>();
public FirebaseHelper(DatabaseReference db) {
this.db = db;
}
//READ THEN RETURN ARRAYLIST FOR SEARCH ITEMS IN CASE OF SEARCHING ABOUT ITEM
public ArrayList<Paints> retrieveSearch(final String item) {
db.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
fetchDataSearch(dataSnapshot,item);
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
fetchDataSearch(dataSnapshot,item);
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
return paints;
}
//IMPLEMENT FETCH DATA AND FILL ARRAYLIST FOR SEARCH
private void fetchDataSearch( DataSnapshot dataSnapshot,String item)
{
paints.clear();
//sorting and searching
final DatabaseReference myRef = db.child("items");
Query query = myRef.orderByChild("type").startAt(item)
.endAt(item + "\uf8ff");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot messageSnapshot : dataSnapshot.getChildren()) {
Paints paint=messageSnapshot.getValue(Paints.class);
paints.add(paint);
//Toast.makeText(FindDataActivity.this, "found " + type + " unit: " + unit + " price " + price, Toast.LENGTH_LONG).show();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
In your MyAdapter class you must create a method like this:
public void updateAdapter(ArrayList<Paints> paint){
this.paint= paint;
notifyDataSetChanged();
}
In your search method replace adapter.notifyDataSetChanged(); for adapter.updateAdapter(p);
I'm using Firebase to populate my RecyclerView, but the problem is that every time I open the app, I need to swipe down to refresh and then the list of items is available.
Here is my code
public class MainActivity extends AppCompatActivity {
private static final int RC_PHOTO_PICKER = 2;
DatabaseReference db;
FirebaseHelper helper;
MyAdapter adapter;
RecyclerView rv;
EditText nameEditTxt,grpTxt,descTxt,linkTxt;
FirebaseAuth.AuthStateListener authListener;
SwipeRefreshLayout swipeRefresh;
Uri downloadUrl;
String Admin_code;
FirebaseStorage mfirebaseStorage;
private StorageReference mEventPhotoReference;
FloatingActionButton fab;
SharedPreferences sharedPreferences;
ProgressBar spinner;
static boolean calledAlready=false;
public MyAdapter adapter1;
#RequiresApi(api = Build.VERSION_CODES.KITKAT)
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
spinner = (ProgressBar)findViewById(R.id.progressBar);
spinner.setVisibility(View.GONE);
mfirebaseStorage=FirebaseStorage.getInstance();
if(!calledAlready){
FirebaseDatabase.getInstance().setPersistenceEnabled(true);
calledAlready=true;
}
swipeRefresh=(SwipeRefreshLayout)findViewById(R.id.swiperefresh);
//SETUP RECYCLER
rv = (RecyclerView) findViewById(R.id.rv);
rv.setLayoutManager(new LinearLayoutManager(this));
//INITIALIZE FIREBASE DB
db= FirebaseDatabase.getInstance().getReference();
mEventPhotoReference=mfirebaseStorage.getReference().child("Event Photos");
helper=new FirebaseHelper(db);
//ADAPTER
adapter=new MyAdapter(this,helper.retrieve());
rv.setAdapter(adapter);
adapter.notifyDataSetChanged();
swipeRefresh.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
rv.setAdapter(adapter);
swipeRefresh.setRefreshing(false);
}
});
sharedPreferences= PreferenceManager.getDefaultSharedPreferences(this);
Admin_code=sharedPreferences.getString(getString(R.string.Admin_code),getString(R.string.Admin_default_value));
Log.e("MainActivity","" + Admin_code);
fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
displayInputDialog();
}
});
fab.setVisibility(View.GONE);
showBtn();
}
#RequiresApi(api = Build.VERSION_CODES.KITKAT)
#Override
protected void onResume() {
showBtn();
super.onResume();
}
#RequiresApi(api = Build.VERSION_CODES.KITKAT)
public void showBtn(){
Admin_code=sharedPreferences.getString(getString(R.string.Admin_code),getString(R.string.Admin_default_value));
if(Objects.equals(Admin_code, "28011996")){
fab.setVisibility(View.VISIBLE);
}
else
fab.setVisibility(View.GONE);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_logout) {
FirebaseAuth.getInstance().signOut();
startActivity(new Intent(MainActivity.this, LoginActivity.class));
return true;
}
if(id==R.id.settings){
Intent settingsIntent=new Intent(this,Settings.class);
startActivity(settingsIntent);
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if ((requestCode& 0xffff) == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
Uri selectedImageUri = data.getData();
StorageReference photoRef=mEventPhotoReference.child(selectedImageUri.getLastPathSegment());
photoRef.putFile(selectedImageUri)
.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
// When the image has successfully uploaded, we get its download URL
downloadUrl = taskSnapshot.getDownloadUrl();
Toast.makeText(MainActivity.this,"Photo selected successfully",Toast.LENGTH_LONG).show();
}
}).addOnFailureListener(this, new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(MainActivity.this,"there was a problem uploading photo",Toast.LENGTH_LONG).show();
}
});
}
}
//DISPLAY INPUT DIALOG
private void displayInputDialog()
{
Dialog d=new Dialog(this);
d.setTitle("Save To Firebase");
d.setContentView(R.layout.input_dialog);
nameEditTxt= (EditText) d.findViewById(R.id.nameEditText);
grpTxt= (EditText) d.findViewById(R.id.propellantEditText);
descTxt= (EditText) d.findViewById(R.id.descEditText);
Button saveBtn= (Button) d.findViewById(R.id.saveBtn);
Button photoBtn=(Button)d.findViewById(R.id.photoBtn);
linkTxt = (EditText) d.findViewById(R.id.linkEditText);
photoBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent=new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);
}
});
//SAVE
saveBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//GET DATA
String name=nameEditTxt.getText().toString();
String propellant=grpTxt.getText().toString();
String desc=descTxt.getText().toString();
String link=linkTxt.getText().toString();
Long tsLong = System.currentTimeMillis()/1000;
String ts = tsLong.toString();
//SET DATA
Spacecraft s=new Spacecraft();
s.setName(name);
s.setPropellant(propellant);
s.setDescription(desc);
s.setLink(link);
s.setImageUrl(downloadUrl.toString());
s.setTimestamp(ts);
//SIMPLE VALIDATION
if(name != null && name.length()>0)
{
//THEN SAVE
if(helper.save(s))
{
//IF SAVED CLEAR EDITXT
nameEditTxt.setText("");
grpTxt.setText("");
descTxt.setText("");
linkTxt.setText("");
downloadUrl=null;
adapter=new MyAdapter(MainActivity.this,helper.retrieve());
rv.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
}else
{
Toast.makeText(MainActivity.this, "Name Must Not Be Empty", Toast.LENGTH_SHORT).show();
}
}
});
d.show();
}
After Searching for a while, I found out that I should use notifyDataSetChanged(); but it doesn't work.
Here is my helper class where I'm fetching data:
public class FirebaseHelper {
DatabaseReference db;
Boolean saved=null;
ArrayList<Spacecraft> spacecrafts=new ArrayList<>();
public FirebaseHelper(DatabaseReference db) {
this.db = db;
}
//WRITE IF NOT NULL
public Boolean save(Spacecraft spacecraft)
{
if(spacecraft==null)
{
saved=false;
}else
{
try
{
db.child("Spacecraft").push().setValue(spacecraft);
saved=true;
}catch (DatabaseException e)
{
e.printStackTrace();
saved=false;
}
}
return saved;
}
//IMPLEMENT FETCH DATA AND FILL ARRAYLIST
private void fetchData(DataSnapshot dataSnapshot)
{
spacecrafts.clear();
for (DataSnapshot ds : dataSnapshot.getChildren())
{
Spacecraft spacecraft=ds.getValue(Spacecraft.class);
spacecrafts.add(spacecraft);
}
}
//READ THEN RETURN ARRAYLIST
public ArrayList<Spacecraft> retrieve() {
db.addChildEventListener(new ChildEventListener() {
#Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
fetchData(dataSnapshot);
}
#Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
fetchData(dataSnapshot);
}
#Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
fetchData(dataSnapshot);
}
#Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
return spacecrafts;
}
It'll be great if someone could help me out here. This is the last problem in my project.
The problem is due to the adapter not knowing about the data that has been fetched asynchronously. Let's try to look at your code step-by-step:
adapter = new MyAdapter(this, helper.retrieve());
helper.retrieve() will initiate an asynchronous request to fetch data from firebase and immediately returns an empty ArrayList (as the data from firebase hasn't reached the app yet).
rv.setAdapter(adapter);
This line sets the adapter to recyclerView, which has an empty arraylist as data, so it won't show anything on the UI.
After the data is received from firebase, ArrayList<Spacecraft> spacecrafts is updated with new data. But the adapter is not notified about this new data. Ideally, adapter.notifyDataSetChanged() should be called after new data is put into the array list.
Hence, when you swipe to refresh after the initial call, the adapter is set to recycler view, leading to an internal call to notifyDataSetChanged(), which in turn loads the new data on to the UI.
Easiest solution is to notify the adapter when new data is received from Firebase. Below is the pseudo code for it -
Create an interface OnFirebaseDataChanged and add a method void dataChanged(); to it.
MainAcitivty should implement this interface and the implementation of that method should call adapter.notifyDataSetChanged()
helper = new FirebaseHelper(db); should be changed to helper = new FirebaseHelper(db, this);
FirebaseHelper's constructor should have a 2nd parameter of type OnFirebaseDataChanged and should save it in a field called dataChangeListener.
Add a line at the end of fetchData method in FirebaseHelper dataChangeListener.dataChanged();
The ideal solution would be to architect the code differently, but that topic is out of scope of this question.
I'm getting error on getUid()
final String user_id = mAuth.getCurrentUser().getUid();
and this my activity code :
public class MainActivity extends AppCompatActivity {
private RecyclerView postList;
private DatabaseReference mDatabase;
private DatabaseReference mDatabaseUsers;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
mAuthListener = new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() == null){
Intent loginIntent = new Intent(MainActivity.this, LoginActivity.class);
loginIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(loginIntent);
}
}
};
mDatabase = FirebaseDatabase.getInstance().getReference().child("Blog");
mDatabaseUsers = FirebaseDatabase.getInstance().getReference().child("Users");
mDatabase.keepSynced(true);
mDatabaseUsers.keepSynced(true);
postList = (RecyclerView) findViewById(R.id.post_list);
postList.setHasFixedSize(true);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
layoutManager.setReverseLayout(true);
layoutManager.setStackFromEnd(true);
postList.setLayoutManager(layoutManager);
}
#Override
protected void onStart() {
super.onStart();
CheckUserExist();
mAuth.addAuthStateListener(mAuthListener);
FirebaseRecyclerAdapter<Blog, BlogViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Blog, BlogViewHolder>(
Blog.class,
R.layout.post_row,
BlogViewHolder.class,
mDatabase
) {
#Override
protected void populateViewHolder(BlogViewHolder viewHolder, Blog model, int position) {
viewHolder.setTitle(model.getTitle());
viewHolder.setDesc(model.getDescription());
viewHolder.setImage(getApplicationContext(), model.getImage());
}
};
postList.setAdapter(firebaseRecyclerAdapter);
}
private void CheckUserExist() {
final String user_id = mAuth.getCurrentUser().getUid();
mDatabaseUsers.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (!dataSnapshot.hasChild(user_id)){
Intent SetupIntent = new Intent(MainActivity.this, SetupActivity.class);
SetupIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(SetupIntent);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
public static class BlogViewHolder extends RecyclerView.ViewHolder{
View mView;
public BlogViewHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void setTitle(String title){
TextView post_title = (TextView) mView.findViewById(R.id.post_title);
post_title.setText(title);
}
public void setDesc(String desc){
TextView post_desc = (TextView) mView.findViewById(R.id.post_desc);
post_desc.setText(desc);
}
public void setImage(final Context ctx, final String image){
final ImageView post_image = (ImageView) mView.findViewById(R.id.post_img);
// Picasso.with(ctx).load(image).into(post_image);
Picasso.with(ctx).load(image).networkPolicy(NetworkPolicy.OFFLINE).into(post_image, new Callback() {
#Override
public void onSuccess() {
}
#Override
public void onError() {
Picasso.with(ctx).load(image).into(post_image);
}
});
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.action_add){
startActivity(new Intent(MainActivity.this, PostActivity.class));
}
if (item.getItemId() == R.id.action_logout){
logout();
}
return super.onOptionsItemSelected(item);
}
private void logout() {
mAuth.signOut();
}
}
The problem happens when you try to call mAuth.getCurrentUser().getUid(). Apparently there is no current user at the time, so that call fails.
Instead use:
private void CheckUserExist() {
if (mAuth.getCurrentUser() != null) {
final String user_id = mAuth.getCurrentUser().getUid();
mDatabaseUsers.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (!dataSnapshot.hasChild(user_id)){
Intent SetupIntent = new Intent(MainActivity.this, SetupActivity.class);
SetupIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(SetupIntent);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
In general, you'll want to use an auth state listener for this, similar to the one you already have in onCreate.
In fact, it seems to me that both could easily be folded into a single listener: one that starts the login activity if the user isn't signed in and optionally registers the user with the database if they are.
The code for that:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDatabase = FirebaseDatabase.getInstance().getReference().child("Blog");
mDatabaseUsers = FirebaseDatabase.getInstance().getReference().child("Users");
mDatabase.keepSynced(true);
mDatabaseUsers.keepSynced(true);
postList = (RecyclerView) findViewById(R.id.post_list);
postList.setHasFixedSize(true);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
layoutManager.setReverseLayout(true);
layoutManager.setStackFromEnd(true);
postList.setLayoutManager(layoutManager);
}
#Override
protected void onStart() {
super.onStart();
CheckUserExist();
FirebaseAuth.getInstance().addAuthStateListener(new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user == null){
// The user is not signed in, start login flow
Intent loginIntent = new Intent(MainActivity.this, LoginActivity.class);
loginIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(loginIntent);
}
else {
// The user is signed in, register them in database
String user_id = user.getUid();
mDatabaseUsers.child(user_id).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (!dataSnapshot.exists()){
Intent SetupIntent = new Intent(MainActivity.this, SetupActivity.class);
SetupIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(SetupIntent);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore onCancelled
}
});
}
}
});
FirebaseRecyclerAdapter<Blog, BlogViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Blog, BlogViewHolder>(
Blog.class,
R.layout.post_row,
BlogViewHolder.class,
mDatabase
) {
#Override
protected void populateViewHolder(BlogViewHolder viewHolder, Blog model, int position) {
viewHolder.setTitle(model.getTitle());
viewHolder.setDesc(model.getDescription());
viewHolder.setImage(getApplicationContext(), model.getImage());
}
};
postList.setAdapter(firebaseRecyclerAdapter);
}
I also fixed the way you check if the user already exists in the database. Retrieving all users to then client-side check if one of the keys exists is a waste of bandwidth that will become especially evident as your number of users grows. The code I wrote checks precisely whether this user's UID already exists in the database, which is the minimum data you can check.
It is because you are not initializing mauth.
remove onstart method and copy the code to oncreate. oncreate will be
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
mAuthListener = new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() == null){
Intent loginIntent = new Intent(MainActivity.this, LoginActivity.class);
loginIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(loginIntent);
}
}
};
mDatabase = FirebaseDatabase.getInstance().getReference().child("Blog");
mDatabaseUsers = FirebaseDatabase.getInstance().getReference().child("Users");
mDatabase.keepSynced(true);
mDatabaseUsers.keepSynced(true);
postList = (RecyclerView) findViewById(R.id.post_list);
postList.setHasFixedSize(true);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
layoutManager.setReverseLayout(true);
layoutManager.setStackFromEnd(true);
postList.setLayoutManager(layoutManager);
CheckUserExist();
mAuth.addAuthStateListener(mAuthListener);
FirebaseRecyclerAdapter<Blog, BlogViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Blog, BlogViewHolder>(
Blog.class,
R.layout.post_row,
BlogViewHolder.class,
mDatabase
) {
#Override
protected void populateViewHolder(BlogViewHolder viewHolder, Blog model, int position) {
viewHolder.setTitle(model.getTitle());
viewHolder.setDesc(model.getDescription());
viewHolder.setImage(getApplicationContext(), model.getImage());
}
};
postList.setAdapter(firebaseRecyclerAdapter);
}