我想检查用户是否已经存在或不使用Fire Base Android中的用户数据（手机号码）

Question

我要检查用户已经存在或不使用用户手机号码

这是我的代码

  private void signInWithPhoneAuthCredential(PhoneAuthCredential credential) {
    mAuth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @RequiresApi(api = Build.VERSION_CODES.KITKAT)
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {




                       DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
                       ref.child("users").child(mobile).addListenerForSingleValueEvent(new ValueEventListener() {


                            @Override
                          public void onDataChange(DataSnapshot dataSnapshot) {
                               if(dataSnapshot.exists()){
                                    // use "username" already exists

                                  Toast.makeText(getApplicationContext(), "already account there",
                                          Toast.LENGTH_LONG).show();


                               } else {
                                    Toast.makeText(getApplicationContext(), "account not exist",
                                           Toast.LENGTH_LONG).show();

                               }
                           }

                            @Override
                           public void onCancelled(DatabaseError databaseError) {

                           }
                        });



                         // FirebaseUser userid = FirebaseAuth.getInstance().getCurrentUser();
                    //    String uid = userid.getUid();




                     //   mDatabase = mDatabase.child("Users");
                     //   Map<String, String> userData = new HashMap<String, String>();

                     //  userData.put("Number", mobile);
                     //   userData.put("Password", "mypassword");
                      //  userData.put("Confirmed", "not confiremed");
                      //  userData.put("Email", "jaisonkerala1@gmail.com");


                     //  mDatabase = mDatabase.child(mobile).child(uid);
                    //    mDatabase.setValue(userData);



                        Toast.makeText(getApplicationContext(), "login success",
                                Toast.LENGTH_LONG).show();




                    } else {

                        Toast.makeText(getApplicationContext(), "login faild",
                                Toast.LENGTH_LONG).show();


                        // Sign in failed, display a message and update the UI
                       // Log.w(TAG, "signInWithCredential:failure", task.getException());
                        if (task.getException() instanceof FirebaseAuthInvalidCredentialsException) {
                            // The verification code entered was invalid

                            Toast.makeText(getApplicationContext(), "OTP was wrong",
                                    Toast.LENGTH_LONG).show();

                        }
                    }
                }
            });

数据库截图

我想通过将数据库中的“数字”节点与用户列表或数据进行比较来检查用户是否存在。现在，如果我使用相同的手机号码，