Styjun

When a user registers in my Android app, their data is stored inside a collection, where the document ID is their email address which helps find a user. The password is stored inside the document as well.

So when a user logins, their entered email is checked against a document ID matching that email, if it exists it will log in and display user control panel.

Now after the login, I need to somehow create a user session, so that the user can never go back to the login screen until he logouts. In case the app crashes or lost network connection, a saved user session would be very useful.

Here's my code for the login activity:

import android.content.Intent;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Patterns;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import com.basgeekball.awesomevalidation.AwesomeValidation;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.firestore.CollectionReference;
import com.google.firebase.firestore.DocumentReference;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.FirebaseFirestore;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import static com.basgeekball.awesomevalidation.ValidationStyle.BASIC;

public class SLogin extends AppCompatActivity

public static final String STUDENT_EMAIL = "student_email";
private EditText tEmail;
private EditText tPassword;
private String email = "";

private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference dbUsers;

@Override
protected void onCreate(Bundle savedInstanceState)

 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_slogin);

 tEmail= findViewById(R.id.Email);
 tEmail.addTextChangedListener(new TextWatcher()
 
 @Override
 public void beforeTextChanged(CharSequence s, int start, int count, int after)
 

 

 @Override
 public void onTextChanged(CharSequence s, int start, int before, int count)
 
 email = s.toString();
 

 @Override
 public void afterTextChanged(Editable s)
 

 
 );
 tPassword=findViewById(R.id.Password);

 // Here you simply set saveEmail to empty string because at this moment when activity is
 // created (onCreate) tEmail field is empty. To update this field dynamically you need set
 // addTextChangedListener on tEmail.
 // saveEmail=tEmail.getText().toString();

 dbUsers = db.collection("Students");


//Validation Method
private boolean validate()

 AwesomeValidation mAwesomeValidation = new AwesomeValidation(BASIC);
 mAwesomeValidation.addValidation(tEmail, Patterns.EMAIL_ADDRESS, "Invalid Email Address");
 String regexPassword = "(?=.*[a-z])(?=.*[A-Z])(?=.*[\d])(?=.*[~`!@#\$%\^&\*\(\)\-_\+=\\\[\]\

//Method to check password matching or not
private void passCheck(@NonNull DocumentSnapshot snapshot)

 final String uPass = tPassword.getText().toString();
 final String storedPass = snapshot.getString("password");
 if (storedPass != null && storedPass.equals(uPass))
 
 Intent intent = new Intent(SLogin.this, StudentCP.class);
 intent.putExtra(STUDENT_EMAIL, email);
 startActivity(intent);
 
 else
 
 Toast.makeText(SLogin.this, "Invalid Password!", Toast.LENGTH_LONG).show();
 


public void sLogin(View v)

 if (validate())
 
 DocumentReference dbDocs = dbUsers.document(email);
 dbDocs.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>()
 
 @Override
 public void onComplete(@NonNull Task<DocumentSnapshot> task)
 
 if (task.isSuccessful())
 
 DocumentSnapshot document = task.getResult();
 if (document != null && document.exists())
 
 //Toast.makeText(SLogin.this, "You are registered", Toast.LENGTH_LONG).show();

 // Improved password checking because at first glance I
 // don't see why you call db fetch again to get document
 // because if we are here that means we got matching data
 // and now we only need to check if password match. No need
 // to call get on db again.
 //
 // It's possible to even more optimize calls to DB in case
 // of wrongly typed password. We can cache input email and
 // returned password for that email so in case if user
 // doesn't change email, but types only password again we
 // can compare newly typed password with cached password
 // from previous request so we don't make again new DB
 // request to simply get again same saved password.
 //
 // Currently I haven't implemented caching. It's only idea
 // to think about in future.
 passCheck(document);
 
 else
 
 Toast.makeText(SLogin.this, "You are not registered", Toast.LENGTH_LONG).show();
 
 
 else
 
 Toast.makeText(SLogin.this, "Unable to connect to database", Toast.LENGTH_LONG).show();
 
 
 );
 

public void nUser(View v)

 Intent intent = new Intent(SLogin.this, RegisterActivity.class);
 startActivity(intent);

For best practice add the following class

public class PrefUtilities 

private SharedPreferences preferences;
Context context;


private PrefUtilities(Context context) 
 preferences = PreferenceManager.getDefaultSharedPreferences(context);
 this.context = context;



public static PrefUtilities with(Context context)
 return new PrefUtilities(context);



public void setUserLogin(boolean isUserLogedin)

 preferences.edit().putBoolean(context.getString(R.string.pref_key_user_status),isUserLogedin).apply();



public boolean isUserLogedin()
 return preferences.getBoolean(context.getString(R.string.pref_key_user_status),false);

check for login status inside onCreate method

if(PrefUtilities.with(this).isUserLogedin())

 Intent intent = new Intent(SLogin.this, StudentCP.class);
 intent.putExtra(STUDENT_EMAIL, email);
 startActivity(intent);

Save login status inside passCheck method

private void passCheck(@NonNull DocumentSnapshot snapshot)

 final String uPass = tPassword.getText().toString();
 final String storedPass = snapshot.getString("password");
 if (storedPass != null && storedPass.equals(uPass))
 

 PrefUtilities.with(this).setUserLogin(true); 

 Intent intent = new Intent(SLogin.this, StudentCP.class);
 intent.putExtra(STUDENT_EMAIL, email);
 startActivity(intent);
 
 else
 
 Toast.makeText(SLogin.this, "Invalid Password!", Toast.LENGTH_LONG).show();
 

When user logout use bellow method to change SharedPreferences

PrefUtilities.with(this).setUserLogin(false);

You can also add other methods in PrefUtilities class saving user Email