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Check if a value exist in more then on child Firebase Database in Android

I'm developing an android application for college project using Java and Firebase. I want to store the details of faculties working in college like name,email,department etc based on their position. I have created 3 child nodes HOD,Class mentor and lecturers inside Faculties as you can see that in here.
my problem is when I want to add the members inside any one these child I want to check if that members email ID is exist in any other childs. For example I want to add a member in HOD child.If this members email existed inside Lecturers child it should display Toast user already existed as Lecturer else it should add member inside Lecturer.
I used this code.
post = "HOD";
databaseReference.child(post).orderByChild("email").equalTo(email).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()){
Toast.makeText(MainActivityAddFaculty.this, "User already exist in "+post, Toast.LENGTH_SHORT).show();
} else {
post = "Class mentor";
databaseReference.child(post).orderByChild("email").equalTo(email).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()){
Toast.makeText(MainActivityAddFaculty.this, "User already exist in "+post, Toast.LENGTH_SHORT).show();
} else {
post = "Lecturer";
databaseReference.child(post).orderByChild("email").equalTo(email).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()){
Toast.makeText(MainActivityAddFaculty.this, "User already exist in "+post, Toast.LENGTH_SHORT).show();
} else {
checkData();
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(MainActivityAddFaculty.this, databaseError.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(MainActivityAddFaculty.this, databaseError.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Toast.makeText(MainActivityAddFaculty.this, databaseError.getMessage(), Toast.LENGTH_SHORT).show();
}
});
It works fine but it's lengthy and also it takes time to check.If there is any better solution that would be very helpful.
This is is my code complete code for adding Faculties.
public class MainActivityAddFaculty extends AppCompatActivity {
private TextInputLayout addName, addEmail;
private TextInputEditText addEditName, addEditEmail;
private Button addBtn;
private Spinner addPositionSpinner,addDeptSpinner,addYearSpinner;
private TextView addPosition,addDept,addYear;
private String sDept = "Select department",sPost = "Select position",sYear = "Select year";
private String position,department,year,post;
private boolean b = false;
private FirebaseDatabase firebaseDatabase;
private FirebaseStorage firebaseStorage;
private DatabaseReference databaseReference,databaseReference2;
private StorageReference storageReference;
LoadingDialog loadingDialog;
private String facultyID;
private String name,email;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_faculty);
setTitle("Add Hod");
assert getSupportActionBar() != null;
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
addName = findViewById(R.id.addFName);
addEmail = findViewById(R.id.addFEmail);
addEditName = findViewById(R.id.addFEditName);
addEditEmail = findViewById(R.id.addFEditEmail);
addBtn = findViewById(R.id.addFBtn);
addPositionSpinner = findViewById(R.id.addFPositionSpinner);
addPosition = findViewById(R.id.addFPosition);
addDeptSpinner = findViewById(R.id.addFDepartmentSpinner);
addDept = findViewById(R.id.addFDepartment);
addYearSpinner = findViewById(R.id.addFYearSpinner);
addYear = findViewById(R.id.addFYear);
addDeptSpinner.setVisibility(View.GONE);
addYearSpinner.setVisibility(View.GONE);
addDept.setVisibility(View.GONE);
addYear.setVisibility(View.GONE);
firebaseDatabase = FirebaseDatabase.getInstance();
databaseReference = firebaseDatabase.getReference("FACULTIES");
facultyID = databaseReference.push().getKey();
loadingDialog = new LoadingDialog(MainActivityAddFaculty.this);
//selectPosition();
//TODO:Select position
List<String> categories = new ArrayList<>();
categories.add(0,"Select position");
categories.add("HOD");
categories.add("Class mentor");
categories.add("Lecturer");
ArrayAdapter<String> dataAdapter;
dataAdapter = new ArrayAdapter(this,android.R.layout.simple_spinner_item,categories);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
addPositionSpinner.setAdapter(dataAdapter);
addPositionSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
addPosition.setText(parent.getSelectedItem().toString());
test();
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
Toast.makeText(MainActivityAddFaculty.this, "Select a position", Toast.LENGTH_SHORT).show();
}
});
addBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
name = addEditName.getText().toString().trim();
email = addEditEmail.getText().toString().trim();
if (TextUtils.isEmpty(name)) {
Toast.makeText(MainActivityAddFaculty.this, "Enter name", Toast.LENGTH_SHORT).show();
}else {
if (TextUtils.isEmpty(email)) {
Toast.makeText(MainActivityAddFaculty.this, "Enter email.", Toast.LENGTH_SHORT).show();
} else {
checkData();
}
}
}
});
}
private void test(){
position = addPositionSpinner.getSelectedItem().toString();
if (position.equals(sPost)){
addDeptSpinner.setVisibility(View.GONE);
addYearSpinner.setVisibility(View.GONE);
addDept.setVisibility(View.GONE);
addYear.setVisibility(View.GONE);
}else if (position.equals("HOD")){
addDeptSpinner.setVisibility(View.VISIBLE);
addYearSpinner.setVisibility(View.GONE);
addDept.setVisibility(View.VISIBLE);
addYear.setVisibility(View.GONE);
} else if (position.equals("Class mentor")){
addDeptSpinner.setVisibility(View.VISIBLE);
addDept.setVisibility(View.VISIBLE);
addYearSpinner.setVisibility(View.VISIBLE);
addYear.setVisibility(View.VISIBLE);
} else if (position.equals("Lecturer")){
addDeptSpinner.setVisibility(View.GONE);
addYearSpinner.setVisibility(View.GONE);
addDept.setVisibility(View.GONE);
addYear.setVisibility(View.GONE);
} else {
addDeptSpinner.setVisibility(View.GONE);
addYearSpinner.setVisibility(View.GONE);
addDept.setVisibility(View.GONE);
addYear.setVisibility(View.GONE);
}
}
private void checkData(){
position = addPositionSpinner.getSelectedItem().toString();
department = addDeptSpinner.getSelectedItem().toString();
year = addYearSpinner.getSelectedItem().toString();
if (position.equals(sPost)){
Toast.makeText(this, "Select position", Toast.LENGTH_SHORT).show();
} else if (position.equals("HOD")){
if (department.equals(sDept)){
Toast.makeText(MainActivityAddFaculty.this, "Select department.", Toast.LENGTH_SHORT).show();
} else {
AddHOD addHOD = new AddHOD(name,position,department,email,facultyID);
databaseReference.child(position).child(facultyID).setValue(addHOD).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
Toast.makeText(MainActivityAddFaculty.this, "Faculty added successfully", Toast.LENGTH_SHORT).show();
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(MainActivityAddFaculty.this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}
}else if (position.equals("Class mentor")){
//add Class mentor process started
if (!department.equals(sDept)){
if (!year.equals(sYear)) {
AddClassMentor addClassMentor = new AddClassMentor(name, position, department, year, email, facultyID);
databaseReference.child(position).child(facultyID).setValue(addClassMentor).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
Toast.makeText(MainActivityAddFaculty.this, "Faculty added successfully", Toast.LENGTH_SHORT).show();
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(MainActivityAddFaculty.this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
});
}else {
Toast.makeText(this, "Select year.", Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(this, "Select department", Toast.LENGTH_SHORT).show();
}
} else if (position.equals("Lecturer")){
AddLecturer addLecturer = new AddLecturer(name,position,email,facultyID);
databaseReference.child(position).child(facultyID).setValue(addLecturer).addOnSuccessListener(new OnSuccessListener<Void>() {
#Override
public void onSuccess(Void aVoid) {
Toast.makeText(MainActivityAddFaculty.this, "Faculty added successfully", Toast.LENGTH_SHORT).show();
}
}).addOnFailureListener(new OnFailureListener() {
#Override
public void onFailure(#NonNull Exception e) {
Toast.makeText(MainActivityAddFaculty.this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
});
} else {
Toast.makeText(this, "Entry is pending.", Toast.LENGTH_SHORT).show();
}
}
}

Firebase's queries work on a list of nodes. Since you have a hierarchy, you'll need to fire the same query for each list you have in there, as you're doing today.
As usual when dealing with NoSQL databases, the solution is to model the data in a way that makes the use-case easiest. If you want to search across all members, store a single list of members:
"members": {
"$memberid": {
"email": "membersemail#institute.edu",
"memberType": "Class mentor" // or "HOD" or "Lecturer"
}
}
With the above structure you only have to execute one query to find all members with a specific email address.
You can either use the above structure to replace the three structures you currently have, or you can use it as an additional structure just for this use-case. Which one to choose depends on the other use-cases in your app, there is no solution that is right for all apps, just the one that works for you.
Enforcing uniques across values as you're doing here, will lead to scalability issues over time, as you:
Need to search across all members, which takes more time as you get more members.
More importantly: you will need to use a transaction to insert new users, to reduce the chances that multiple users claim the same email address at the same time.
This leads to a second scaling problem, as you'll need to run that transaction on the evert-growing /members node.
Finally: a malicious user can bypass the transaction by writing their own code, and still claim any email address.
Ensuring uniqueness on Firebase is only really enforceable if you use those values as the key in a list, so by maintaining a (additional) list of email addresses.
For more on this see:
Firebase security rules to check unique value of a child #AskFirebase
Firebase android : make username unique
How do you prevent duplicate user properties in Firebase?
Firebase realtime database validation username and email

Direct to each activity according to type of user [duplicate]

This question already has answers here:
How to redirect multiple types of users to their respective Activities?
(3 answers)
Closed 3 years ago.
I have created a project which has two types of user (patient and doctor). During login, I need to retrieve the role attribute in the firebase which under the users table.
In my database structure, user type maybe is "doctor" or "patient". During login, I think I need to retrieve the role information and then assign them to different activity in android studio. However, my code seems doesn't work. The application keeps stopped. Is there anyone can help me. Thanks in advance.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
email = findViewById(R.id.email);
psd = findViewById(R.id.psd);
}
public void clicked(View v) {
switch (v.getId()) {
case R.id.login:
LoginUser();
break;
case R.id.register:
Intent intent = new Intent(this, ChooseRole.class);
startActivity(intent);
break;
}
}
public void LoginUser() {
String email1 = email.getText().toString().trim();
String psd1 = psd.getText().toString().trim();
mAuth.signInWithEmailAndPassword(email1, psd1)
.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
#Override
public void onComplete(#NonNull Task<AuthResult> task) {
if (task.isSuccessful()) {
indentify();
finish();
} else {
Toast.makeText(Login.this, "couldn't login",
Toast.LENGTH_SHORT).show();
}
}
});
}
public void indentify() {
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
FirebaseDatabase.getInstance().getReference(uid).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
long points = dataSnapshot.child("role").getValue(Long.class);
String role = String.valueOf(points);
if(role=="patient"){
Intent intent = new Intent(Login.this, HomePage.class);
startActivity(intent);
}
else{
Intent intent = new Intent(Login.this, HomePage2.class);
startActivity(intent);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
});
}
}
Hi guys, I changed it like this and it is successful. Thanks for everyone helping :D
public void LoginUser(){
String email1 = email.getText().toString().trim();
String psd1 = psd.getText().toString().trim();
mAuth.signInWithEmailAndPassword(email1, psd1)
.addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
#Override
public void onComplete(#NonNull Task<AuthResult> task) {
if (task.isSuccessful()){
currentUser = mAuth.getCurrentUser();
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
FirebaseDatabase.getInstance().getReference("users").child(uid).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.child("role").getValue(String.class).equals("patient")) {
startActivity(new Intent(Login.this, HomePage.class));
return;
}
if (dataSnapshot.child("role").getValue(String.class).equals("doctor")) {
startActivity(new Intent(Login.this, HomePage2.class));
return;
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
});
}else {
Toast.makeText(Login.this, "couldn't login",
Toast.LENGTH_SHORT).show();
}
}
});
}

Since in your database you have a node called users, then add a reference to that node, for example:
FirebaseDatabase.getInstance().getReference("users").child(uid).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Then do the following:
Change this:
if(role=="patient"){
into this:
if(role.equals("patient")){
You need to use equals() when you want to compare the value of each object.

Check if is user first login on Android App using Firebase Auth and Database

I am making an chat app and I want to do the following:
When starting the MainActivity, check if the user is logged in. If not, start FirebaseAuthUI.
But FirebaseAuth only supports a few parameters and, to add more, I created a Database node do each user, which store other parameters.
To get this parameters, after finishing FirebaseAuth, the user is redirected to an Activity that get all extra information and store in the user's node in the Database. All of this is working just fine.
But after the user fill the information in this Info Activity and finish the register, it should go back to MainActivity and stay there. How can I do that?
I am trying it this way:
I added to each user a Boolean variable called userCompleted, which informs if the user have already gave their information. I check if this variable is false, and if so, I call the Info Activity intent and, in the when the user press the button to complete the registration in this Activity, it sets the userCompleted value to true in the user node in the Database and then start an intent that leads to MainActivity.
The problem is that in the Database, userCompleted is set to true and then immediately goes back to false, and I don't know why. Also, I guess I am having trouble on reading userCompleted from the Database, probably because I haven't worked much with asynchronous tasks.
I used a variable isUserCompleted declared in Main Activity to get track of the userCompleted value.
A way to check if is the first time the user is logging in would be useful too, although it wouldn't solve my whole problem.
This is my current code:
(if need more to try to understand the problem just ask in the comments)
Create AuthStateListener
public void setAuthStateListener(){
mAuthStateListener = new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
onSignInInitialize(user);
Log.d(TAG, "userUid = " + user.getUid());
Toast.makeText(SearchActivity.this, "Signed in!", Toast.LENGTH_SHORT).show();
} else {
onSignOutCleanup();
startLoginUI();
}
}
};
}
onSignInInitialize()
public void onSignInInitialize(final FirebaseUser user){
mLoggedFBUser = user;
mUserReference = mUsersDatabaseReference.child(user.getUid());
mUserReference.child("uid").setValue(user.getUid());
mUserReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
isUserCompleted = user.isUserCompleted();
Log.d(TAG, "UserCompleted (onDataChanged) "+ isUserCompleted);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
Log.d(TAG, "UserCompleted (Before startActivity if) "+ isUserCompleted);
if (!isUserCompleted) {
startCreateProfileActivity(user);
}
Log.d(TAG, "UserCompleted (After startActivity if) "+ isUserCompleted);
mUserReference.child("username").setValue(user.getDisplayName());
mUserReference.child("email").setValue(user.getEmail());
attachChildEventListener();
}
Go back to Main Activity
mFinishButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
mUserDatabaseReference.child("userCompleted").setValue(true);
Intent intent = new Intent (CreateVolunteerProfile.this, SearchActivity.class);
startActivity(intent);
}
});
Entire MainActivity block (Actually it's called SearchActivity)
public class SearchActivity extends AppCompatActivity implements RecyclerAdapter.UserItemClickListener {
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private RecyclerView.LayoutManager layoutManager;
private ArrayList<User> users = new ArrayList<User>();
private String mLoggedUserId = "user2";
private String mLoggedUsername;
private User mLoggedUser;
private FirebaseUser mLoggedFBUser;
//private boolean isUserCompleted;
private SharedPreferences mSharedPreferences;
private SharedPreferences.Editor mPreferencesEditor;
private boolean firstTime = true;
private static final String TAG = "Search Activity";
private static final int USER_CLICK = 1;
private static final int RC_SIGN_IN = 1;
private static final int RC_CREATE_PROFILE = 2;
//Firebase
private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference mUsersDatabaseReference;
private DatabaseReference mUserReference;
private ChildEventListener mChildEventListener;
private FirebaseAuth mFirebaseAuth;
private FirebaseAuth.AuthStateListener mAuthStateListener;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
View loadingView = findViewById(R.id.cl_loading);
loadingView.setVisibility(View.VISIBLE);
//RecyclerView
recyclerView = findViewById(R.id.rv_users);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
adapter = new RecyclerAdapter(users, this);
recyclerView.setAdapter(adapter);
//Firebase
mFirebaseDatabase = FirebaseDatabase.getInstance();
mFirebaseAuth = FirebaseAuth.getInstance();
mUsersDatabaseReference = mFirebaseDatabase.getReference().child("users");
setAuthStateListener();
loadingView.setVisibility(View.GONE);
}
#Override
protected void onResume() {
super.onResume();
mFirebaseAuth.addAuthStateListener(mAuthStateListener);
}
#Override
protected void onPause() {
super.onPause();
if (mAuthStateListener != null)
mFirebaseAuth.removeAuthStateListener(mAuthStateListener);
detachChildEventListener();
clearAdapter();
}
#Override
protected void onSaveInstanceState(Bundle outState) {
Log.wtf(TAG, "onSaveInstanceState userId = "+ mLoggedUserId);
//Log.wtf(TAG, "UserCompleted (onSaveInstanceState) " + isUserCompleted);
outState.putString("userId", mLoggedUserId);
//outState.putBoolean("isUserCompleted", isUserCompleted);
super.onSaveInstanceState(outState);
}
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
mLoggedUserId = savedInstanceState.getString("userId");
//isUserCompleted = savedInstanceState.getBoolean("isUserCompleted");
//Log.wtf(TAG, "UserCompleted (onRestoreInstanceState) " + isUserCompleted);
Log.wtf(TAG, "onRestoreInstanceState userId = "+ mLoggedUserId);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, #Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if((requestCode == RC_SIGN_IN) && firstTime){
if (resultCode == RESULT_OK){
//Toast.makeText(this, "Signed in!", Toast.LENGTH_SHORT).show();
} else if (resultCode == RESULT_CANCELED){
Toast.makeText(this, "Sign in canceled!", Toast.LENGTH_SHORT).show();
finish();
}
}
if((requestCode == RC_CREATE_PROFILE)){
if (resultCode == RESULT_OK){
//isUserCompleted = true;
}
}
}
#Override
public void onUserItemClick(int clickedUserIndex) {
Intent intent = new Intent (this, ChatActivity.class);
FirebaseUser user = mFirebaseAuth.getCurrentUser();
if(user != null) {
mLoggedUserId = user.getUid();
intent.putExtra("user1", mLoggedUserId);
String mUserRecieverId = users.get(clickedUserIndex).getUid();
intent.putExtra("user2", mUserRecieverId);
Log.wtf(TAG, "SearchActivity // user = " + users.get(clickedUserIndex));
Log.wtf("1", "SearchActivity // mLoggedUserId = " + mLoggedUserId + " // users.getUid() = " + users.get(clickedUserIndex).getUid());
startActivityForResult(intent, USER_CLICK);
}
else {
Toast.makeText(this, "ERROR", Toast.LENGTH_SHORT).show();
}
}
public void setAuthStateListener(){
mAuthStateListener = new FirebaseAuth.AuthStateListener() {
#Override
public void onAuthStateChanged(#NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
mUserReference = mUsersDatabaseReference.child(user.getUid());
onSignInInitialize(user);
Log.wtf(TAG, "userUid = " + user.getUid());
Toast.makeText(SearchActivity.this, "Signed in!", Toast.LENGTH_SHORT).show();
} else {
onSignOutCleanup();
startLoginUI();
}
}
};
}
public void onSignInInitialize(final FirebaseUser user){
mLoggedFBUser = user;
mUserReference = mUsersDatabaseReference.child(user.getUid());
mUserReference.child("uid").setValue(user.getUid());
boolean isUserCompleted = false;
mUserReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
isUserCompleted = user.isUserCompleted();
Log.wtf(TAG, "UserCompleted (onDataChanged) "+ isUserCompleted);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
Log.wtf(TAG, "UserCompleted (Before startActivity if) "+ isUserCompleted);
if (!isUserCompleted) {
startCreateProfileActivity(user);
}
Log.wtf(TAG, "UserCompleted (After startActivity if) "+ isUserCompleted);
mUserReference.child("username").setValue(user.getDisplayName());
mUserReference.child("email").setValue(user.getEmail());
attachChildEventListener();
}
public void onSignOutCleanup(){
mLoggedUser = null;
mLoggedUserId = null;
mLoggedUsername = null;
detachChildEventListener();
clearAdapter();
}
public void attachChildEventListener(){
if (mChildEventListener == null){
mChildEventListener = new ChildEventListener() {
#Override
public void onChildAdded(#NonNull DataSnapshot dataSnapshot, #Nullable String s) {
User user = dataSnapshot.getValue(User.class);
users.add(user);
Log.d(TAG, "onChildAdded userId = "+ user.getUid());
//adapter.notifyItemInserted(users.size()-1);
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) { }
};
}
mUsersDatabaseReference.addChildEventListener(mChildEventListener);
}
public void detachChildEventListener(){
if (mChildEventListener != null){
mUsersDatabaseReference.removeEventListener(mChildEventListener);
mChildEventListener = null;
}
}
public void clearAdapter() {
final int size = users.size();
if (size > 0) {
for (int i = 0; i < size; i++) {
users.remove(0);
}
adapter.notifyItemRangeRemoved(0, size);
}
}
public void startCreateProfileActivity(FirebaseUser user){
mUsersDatabaseReference.child(user.getUid()).child("userCompleted").setValue(false);
Intent intent = new Intent(SearchActivity.this, CreateProfileActivity.class);
intent.putExtra("userId", user.getUid());
startActivityForResult(intent, RC_CREATE_PROFILE);
}
public void startLoginUI(){
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setIsSmartLockEnabled(false)
.setLogo(R.mipmap.logo)
.setAvailableProviders(Arrays.asList(
new AuthUI.IdpConfig.GoogleBuilder().build(),
//new AuthUI.IdpConfig.FacebookBuilder().build(),
//new AuthUI.IdpConfig.TwitterBuilder().build(),
//new AuthUI.IdpConfig.GitHubBuilder().build(),
new AuthUI.IdpConfig.EmailBuilder().build()))
//new AuthUI.IdpConfig.PhoneBuilder().build(),
//new AuthUI.IdpConfig.AnonymousBuilder().build()))
.build(),
RC_SIGN_IN);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater menuInflater = getMenuInflater();
menuInflater.inflate(R.menu.search_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()){
case R.id.sign_out_item:
AuthUI.getInstance().signOut(this);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}

I think the simplest way is if a user clicked on finish Btn successfully make a flag with true else make it false
in your MainActivity
firebase.auth().onAuthStateChanged(function(user) {
// User signed in and not registered
if (user&&!isPressedOnFinishBtn) {
// User is signed in.
}
user clicked on finish btn
else if(isPressedOnFinishBtn) {
// No user is signed in.
}
});

This is how you can do that .
Create a method inside your Login activity .
private void AllowUserToLogin() {
String userName = userEmail.getText().toString();
String userPass = userPassword.getText().toString();
if (TextUtils.isEmpty(userName) || TextUtils.isEmpty(userPass)) {
Toast.makeText(this, "Enter user Name / password first . . .", Toast.LENGTH_SHORT).show();
} else {
dialogBar.setTitle("Sign In ");
dialogBar.setMessage("Please Wait . . .");
dialogBar.setCanceledOnTouchOutside(true);
dialogBar.show();
mAuth.signInWithEmailAndPassword(userName, userPass)
.addOnCompleteListener(new OnCompleteListener<AuthResult>() {
#Override
public void onComplete(#NonNull Task<AuthResult> task) {
if (task.isSuccessful()) {
String currentUserID = mAuth.getCurrentUser().getUid();
String deviceToken = Settings.Secure.getString(getApplicationContext().getContentResolver(),
Settings.Secure.ANDROID_ID);
UsersRef.child(currentUserID).child("device_token")
.setValue(deviceToken)
.addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if(task.isSuccessful()){
sendUserToMainActivity();
Toast.makeText(LoginPage.this, "Logged in Successfull . . . ", Toast.LENGTH_SHORT).show();
dialogBar.dismiss();
}
}
});
} else {
String error = task.getException().toString();
Toast.makeText(LoginPage.this, "Wrong Email or Password: " + error, Toast.LENGTH_SHORT).show();
dialogBar.dismiss();
}
}
});
}
}
and on ur onClick() method .
#Override
public void onClick(View v) {
if (v == needNewAccount) {
sendUserToRegisterActivity();
} else if (v == loginButton) {
AllowUserToLogin();
}else if(v == phone_button){
Intent phoneLoginIntent = new Intent(LoginPage.this , PhoneLoginActivity.class);
startActivity(phoneLoginIntent);
}
}
this is sendUserToRegisterActivity()
private void sendUserToRegisterActivity() {
Intent registerIntent = new Intent(LoginPage.this, RegisterationForm.class);
startActivity(registerIntent);
}
This is sendUserToMainActivity() .
private void sendUserToMainActivity() {
Intent mainIntent = new Intent(LoginPage.this, MainActivity.class);
mainIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(mainIntent);
finish();
}

Firebase ListenerForSingleValueEvent not firing onCreate but is onResume()

So i have a MainActivity that should bring up a set of data from Firebase when it's onCreate method is run however, the List is returning 0 each time.
Notably when i go to another activity (pause MainActivity) and then onResume() is called when going back to MainActivity the method runs fine returning the required results.....i suspect this is sometihng to do with the activity life cycle but can't seem to pin it down.
Placing the method in both onCreate(), onStart() and onResume() has the same result of 0 and the same behaviour in terms of navigating to another activity and coming back gives me the data.
Any thoughts?
My onResume() method:
#Override
protected void onResume() {
super.onResume();
if (ContextCompat.checkSelfPermission(this,Manifest.permission.ACCESS_FINE_LOCATION)!= PackageManager.PERMISSION_GRANTED){
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION},REQUEST_LOCATION);
}
else if (ContextCompat.checkSelfPermission(this,Manifest.permission.WRITE_EXTERNAL_STORAGE)!= PackageManager.PERMISSION_GRANTED){
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},REQUEST_EXTERNAL);
}
try{
mFusedLocationClient.getLastLocation().addOnSuccessListener(this, new OnSuccessListener<Location>() {
#Override
public void onSuccess(Location location) {
FirebaseAuth auth = FirebaseAuth.getInstance();
double lattitude = location.getLatitude();
double longitude = location.getLongitude();
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("GeoFire");
GeoFire geofire = new GeoFire(ref);
geofire.setLocation(auth.getUid(), new GeoLocation(lattitude, longitude), new GeoFire.CompletionListener() {
#Override
public void onComplete(String key, DatabaseError error) {
if (error != null) {
System.err.println("There was an error saving the location to GeoFire: " + error);
} else {
System.out.println("Location saved on server successfully!");
}
}
});
}
});}
catch (SecurityException e){
}
generateData();
}
mFusedLocationClient is a instance of the class FusedLocationProvierClient. Documentation can be found here.
GenerateData Method:
userDb.orderByChild("aField").equalTo(constraint).limitToLast(50).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
getUserList(); // runs geolocation
//GENERATE LIST
for (DataSnapshot ds : dataSnapshot.getChildren()) {
try {
User tempUser = ds.getValue(User.class);
userList.add(tempUser);
setActive(userList);
}
Log.d("userListSize", String.valueOf(userList.size()));
} catch (IndexOutOfBoundsException e) {
Log.d("Index EXception", e.getMessage());
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});

Firebase Delete Child onButtonClick

My problem is I cant delete a single child from the firebase database, either nothing happens or it deletes the whole child and all data. I've looked around and tried multiple solutions but for whatever reason mine wont work and I out of ideas why.
Any help is appreciated.
Java class.
//get data passed from viewpasswords and put them into textviews
name.setText(getIntent().getExtras().getString("data"));
password.setText(getIntent().getExtras().getString("pass"));
//get current user id and reference to database
final FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
assert user != null;
userID = user.getUid();
dbRef = FirebaseDatabase.getInstance().getReference();
//button onclick stuff
delete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
DeleteData();
}
});
exit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(DecryptPassword.this, ViewPasswords.class);
startActivity(intent);
}
});
}
private void DeleteData() {
final String passName = name.getText().toString();
Query query = dbRef.child("Passwords").child(userID).orderByChild("PasswordName").equalTo(passName);
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.getChildrenCount() > 0){
for(DataSnapshot itemSnapshot : dataSnapshot.getChildren()){
dataSnapshot.getRef().removeValue();
Toast.makeText(DecryptPassword.this, "Success", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(DecryptPassword.this, ViewPasswords.class);
startActivity(intent);
}
}else{
Toast.makeText(DecryptPassword.this, "Failed to delete", Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText(DecryptPassword.this, "Error occurred sorry", Toast.LENGTH_SHORT).show();
}
});
}
Firebase Database:
Thanks.

dataSnapshot.getRef().removeValue();
Change this part to:
itemSnapshot.removeValue();