Firebase Login Register App with DeviceID

Question

I have created a login register App. I used email and password for registration. I also add that if user registration is successful the device id will save to the database. I want that id the device id is registered with a account the user can't create a new account with that device And i also want that if database device id is matched with the current Device id let user to login or else don't. How can i solve this? By using Query?

Answer 1

Create a Child Named USerId . And try this:

// save data to firebase
     DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
                DatabaseReference ezzeearnRef = rootRef.child("UserId");
                ValueEventListener eventListener = new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                            //here android_id is IMEI number
                        if (dataSnapshot.child(android_id).exists()) {
                            //show what u want
                        } else {
                            //creating a new user
                            firebaseAuth.createUserWithEmailAndPassword(email, password)
                                    .addOnCompleteListener(MainActivity.this, new OnCompleteListener<AuthResult>() {
                                        @Override
                                        public void onComplete(@NonNull Task<AuthResult> task) {
                                            //checking if success
                                            if (task.isSuccessful()) {
                                                DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();

                                                rootRef.child("UserId").child(android_id).setValue(0);

                                                finish();
                                                startActivity(new Intent(MainActivity.this, LoginActivity.class));
                                            } else {
                                                //display some message here
                                                Toast.makeText(MainActivity.this, "Registration Error", Toast.LENGTH_LONG).show();
                                            }
                                            progressDialog.dismiss();
                                        }
                                    });
                        }

Answer 2

public class LoginActivity extends AppCompatActivity {
// vew banding
private ActivityLoginBinding binding;

//fibase atuh
private FirebaseAuth firebaseAuth;

//progress dialog
private ProgressDialog progressDialog;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    binding = ActivityLoginBinding.inflate(getLayoutInflater());
    setContentView(binding.getRoot());

    //inti firbase atuh
    firebaseAuth = FirebaseAuth.getInstance();

    //setup progress dialog
    progressDialog = new ProgressDialog(this);
    progressDialog.setTitle("please wait...");
    progressDialog.setCanceledOnTouchOutside(false);


    // handel click go to regster
    binding.noAccountTv.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            startActivity(new Intent(LoginActivity.this, 
   RegisterActivity.class));
        }
    });

    // handel click bifen login
    binding.loginBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            validataData();

        }
    });

}
private String email ="" , password="";
private void validataData() {

    //getdata
    email = binding.emailEt.getText().toString().trim();
    password = binding.passwordEt.getText().toString().trim();

    //validata data

if (.Patterns.EMAIL_ADDRESS.matcher(email).matches()){

        Toast.makeText(this, "Invalid email pattern...!", Toast.LENGTH_SHORT).show();
    }
    else if (TextUtils.isEmpty(password)){
        Toast.makeText(this, "Enter password...!", 
 Toast.LENGTH_SHORT).show();
    }
    else {
        //data is vaid data login
         loginUser();
}

 }

 private void loginUser() {
    //show progress
    progressDialog.setMessage("Logging In...");
    progressDialog.show();

    //login user
    firebaseAuth.signInWithEmailAndPassword(email,password)
            .addOnSuccessListener(new OnSuccessListener<AuthResult>() {
                @Override
                public void onSuccess(AuthResult authResult) {
                    //login success , chek user if user or admin
                    chekUser();

                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure( Exception e) {
                    //login faild
                    progressDialog.dismiss();
                    Toast.makeText(LoginActivity.this, ""+e.getMessage(), 
 Toast.LENGTH_SHORT).show();

                }
            });
}

private void chekUser() {
    progressDialog.setMessage("Checking User...");

    //chek user if user or admin for realtime database
    //get crunt user
    FirebaseUser firebaseUser=firebaseAuth.getCurrentUser();

    //cheak in db
    DatabaseReference ref = 
   FirebaseDatabase.getInstance().getReference("Users");
    ref.child(firebaseUser.getUid())
            .addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange( DataSnapshot snapshot) {
                    progressDialog.dismiss();
                    //get user typy
                    String userType = 
    ""+snapshot.child("userType").getValue();
                    //chek userType
                    if (userType.equals("0")){
                        // thise is user soimpel open user dshbord
                        startActivity(new Intent(LoginActivity.this, 
     DashboardOneNozom.class));
                        finish();
                    }
                    else if (userType.equals("1")){
                        // thise is admin soimpel open admin dshbord
                        startActivity(new Intent(LoginActivity.this, 
   DashboardTowNozom.class));
                        finish();
                    }
                }

                @Override
                public void onCancelled( DatabaseError error) {

                }
            });
}
}