--- title: User registration - login slug: docs/android/working-with-users/login-android-tutorial description: In this guide you learn how to add user registration and login to your App. image: https://www.back4app.com/images/logo-social.png docTags: createdAt: 2024-03-14T10:52:14.074Z --- # Login and User registration tutorial ## Introduction In this section we will take a look to how to create an app with a simple user registration using [Parse Server core features](https://www.back4app.com/product/parse-server) through Back4App. This tutorial uses a basic app created in Android Studio 4.1.1 with `buildToolsVersion=30.0.2` , `Compile SDK Version = 30.0.2` and `targetSdkVersion 30` :::hint{type="success"} At any time, you can access the complete Android Project built with this tutorial at our Github repositories - [Kotlin Example Repository](https://github.com/templates-back4app/Android-Parse-Sdk-Kotlin) - [Java Example Repository](https://github.com/templates-back4app/Android-Parse-Sdk-Java) ::: ## Goal We will learn how to log in and register using Parse. Here is a preview of what we are gonna achive : ::Image[]{src="https://api.archbee.com/api/optimize/yD3zCY-NNBBIfd0uqcfR5/aN4ASiBVNZ8ziFhqTP4Mb_user-registrationv2.gif" size="50" width="346" height="750" position="center" showCaption="false"} ## Prerequisites :::hint{type="info"} **To complete this tutorial, we need:** - [Android Studio](https://developer.android.com/studio/index.html) - An app created on Back4App. - **Note: **Follow the [New Parse App tutorial](https://www.back4app.com/docs/get-started/new-parse-app) to learn how to create a Parse App on Back4App. - An android app connected to Back4App. - **Note: **Follow the [Install Parse SDK tutoria](https://www.back4app.com/docs/android/parse-android-sdk)l to create an Android Studio Project connected to Back4App. - A device (or[ virtual device](https://developer.android.com/studio/run/managing-avds.html)) running Android 4.1 (Jelly Bean) or newer. ::: ## 1 - Import Library In this step we will import the libraries which we are gonna use in our project: 1. We will add following Parse Classes to our Activities. :::BlockQuote 1 import com.parse.Parse**;** 2 import com.parse.ParseException**;** 3 import com.parse.ParseUser**;** ::: 2\. We will use lambda functions frequently in our project because of that we need to add Java 1.8 to our project via build.gradle(Module\:App) :::BlockQuote 1 compileOptions **\{** 2 sourceCompatibility **JavaVersion.**VERSION\_1\_8 3 targetCompatibility **JavaVersion.**VERSION\_1\_8 4 **}** ::: ## 2 - Sign Up Signing up basically creates a new Parse.User Object in User Class, shown as “User” in your app `Dashboard`. We need to set at least two properties when creating a new user => `ParseUser.setUsername()` and `ParseUser.setPassword()`. The method used for saving the new user on Android is `ParseUser.signUpInBackground()`, which may come together with a callback function. :::hint{type="info"} **Note**: Objects of this special class are not saved on the `Dashboard` with `ParseObject.save()` method. ::: To make `SignUpActivity` work, follow these steps: 1. Import :::BlockQuote 1 import com.parse.SignUpCallback**;** ::: into your `SignUpActivity`, in addition to the dependencies imported in **Step 1**. 2\. To implement user registration, simply use the following code in the`onCreate()` method: :::CodeblockTabs ```java 1 ParseUser user = new ParseUser(); 2 // Set the user's username and password, which can be obtained by a forms 3 user.setUsername( ""); 4 user.setPassword( ""); 5 user.signUpInBackground(new SignUpCallback() { 6 @Override 7 public void done(ParseException e) { 8 if (e == null) { 9 showAlert("Successful Sign Up!", "Welcome" + "" +"!"); 10 } else { 11 ParseUser.logOut(); 12 Toast.makeText(SignUpActivity.this, e.getMessage(), Toast.LENGTH_LONG).show(); 13 } 14 } 15 }); ``` ```kotlin 1 val user = ParseUser(); 2 // Set the user's username and password, which can be obtained by a forms 3 user.setUsername(""); 4 user.setPassword(""); 5 user.signUpInBackground(SignUpCallback() { 6 if (it == null) { 7 showAlert("Successful Sign Up!", "Welcome" + "" + "!"); 8 } else { 9 ParseUser.logOut(); 10 Toast.makeText(this, it.message, Toast.LENGTH_LONG).show(); 11 } 12 }); ``` ::: :::hint{type="info"} In the example project, this code is placed inside a `SIGN UP` button callback. Also, username and password are caught using **Edit Texts**. ::: 3\. It’s interesting to add an additional method to display Alert Dialogs and make the process look more professional. The method below do this: :::CodeblockTabs ```java 1 private void showAlert(String title,String message){ 2 AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this) 3 .setTitle(title) 4 .setMessage(message) 5 .setPositiveButton("OK", new DialogInterface.OnClickListener() { 6 @Override 7 public void onClick(DialogInterface dialog, int which) { 8 dialog.cancel(); 9 // don't forget to change the line below with the names of your Activities 10 Intent intent = new Intent(SignUpActivity.this, LogoutActivity.class); 11 intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK); 12 startActivity(intent); 13 } 14 }); 15 AlertDialog ok = builder.create(); 16 ok.show(); 17 } ``` ```kotlin 1 private fun showAlert(title: String, message: String) { 2 val builder = AlertDialog.Builder(this) 3 .setTitle(title) 4 .setMessage(message) 5 .setPositiveButton("OK") { dialog, which -> 6 dialog.cancel() 7 // don't forget to change the line below with the names of your Activities 8 val intent = Intent(this, LogoutActivity::class.java) 9 intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK or Intent.FLAG_ACTIVITY_NEW_TASK) 10 startActivity(intent) 11 } 12 val ok = builder.create() 13 ok.show() 14 } ``` ::: ## 3 - Log in Logging in creates a Session object, which points to the User logged in. If login is successful, `ParseUser.getCurrentUser()` returns a User object, and a Session object which created in the `Dashboard`. Otherwise, if the target username does not exist, or the password is wrong, it returns null. The method used to perform the login action is `ParseUser.logInInBackground()`, which requires as many arguments as the strings of username and password, and may call a callback function. :::hint{type="info"} **Note:** After signing up, login is performed automatically. ::: To make `LoginActivity` work, follow these steps: 1. Import into your`LoginActivity`, in addition to the dependencies imported in the **Step 1:** :::BlockQuote 1 import com.parse.LogInCallback**;** ::: 2\. To implement user login function, simply use the code: :::CodeblockTabs ```java 1 private void login(String username, String password) { 2 progressDialog.show(); 3 ParseUser.logInInBackground(username, password, (parseUser, e) -> { 4 progressDialog.dismiss(); 5 if (parseUser != null) { 6 showAlert("Successful Login", "Welcome back " + username + " !"); 7 } else { 8 ParseUser.logOut(); 9 Toast.makeText(LoginActivity.this, e.getMessage(), Toast.LENGTH_LONG).show(); 10 } 11 }); 12 } ``` ```kotlin 1 fun login(username: String, password: String) { 2 progressDialog?.show() 3 ParseUser.logInInBackground(username,password) { parseUser: ParseUser?, parseException: ParseException? -> 4 progressDialog?.dismiss() 5 if (parseUser != null) { 6 showAlert("Successful Login", "Welcome back " + username + " !") 7 } else { 8 ParseUser.logOut() 9 if (parseException != null) { 10 Toast.makeText(this, parseException.message, Toast.LENGTH_LONG).show() 11 } 12 } 13 } 14 } ``` ::: :::hint{type="info"} In the example project, this code is placed inside a `LOG IN` button callback. Also, username and password are caught using **Edit Texts**. ::: :::hint{type="info"} The method `showAlert` is the same that you added in the `SignUpActivity`, don’t forget to change its `Intent` arguments though. ::: ## 4 - Log Out Logging out deletes the active Session object for the logged User. The method used to perform log out is `ParseUser.logOutInBackground()`. To implement user log out, simply use the code below, in the `LogoutActivity`: :::CodeblockTabs ```java 1 ParseUser.logOutInBackground(e -> { 2 progressDialog.dismiss(); 3 if (e == null) 4 showAlert("So, you're going...", "Ok...Bye-bye then"); 5 }); ``` ```kotlin 1 fun login(username: String, password: String) { 2 progressDialog?.show() 3 ParseUser.logInInBackground(username,password) { parseUser: ParseUser?, parseException: ParseException? -> 4 progressDialog?.dismiss() 5 if (parseUser != null) { 6 showAlert("Successful Login", "Welcome back " + username + " !") 7 } else { 8 ParseUser.logOut() 9 if (parseException != null) { 10 Toast.makeText(this, parseException.message, Toast.LENGTH_LONG).show() 11 } 12 } 13 } 14 } ``` ::: :::hint{type="info"} In the example project, this code is placed inside a `LOG OUT` button callback. ::: :::hint{type="info"} The method `showAlert` is the same that you added in the `loginActivity`and`SignUpActivity`, don’t forget to change its `Intent` arguments though. ::: ## 5 - Test your app 1. Run your app and create a couple of users, also try logging in again after registering them. 2. Login at [Back4App Website](https://www.back4app.com/). 3. Find your app and click on `Dashboard`>`Core`>`Browser`>`User`. At this point, you should see your users as displayed below: ![](https://api.archbee.com/api/optimize/yD3zCY-NNBBIfd0uqcfR5/A9nIfbXRgRJQrRuLJDOzG_image.png) :::hint{type="info"} **Note**: Using the codes displayed above, every time you log in with a user, a `Session` is opened in your `Dashboard`, but when the user logs out that particular `Session` ends. Also, whenever an unsuccessful login or sign up attempt occurs, the `Session` opened in Parse Server `Dashboard` is deleted. ::: ## It’s done! Congrats ! Now you can log in, register or log out of your app using Parse Server core features through Back4App!