Kotlin Android Web Service – Volley Library Registration, Log-in, and Log-out Tutorial

In this tutorial, we will create the basic user registration and log-in module using Volley library and JSON. Volley is an HTTP Library which provides the facilities for network connectivity for our app.

The web API of registration and login is created using PHP with MySQL. Before implementing the client side Android application code, first look at the server side API code at https://tutoraspire.com/android-volley-library-registration-login-logout.

In Android application, we will create the three activity class for user registration, user log-in and display the user detail in main activity (as a profile).

Create an activity_main.xml in layout and add the following code. This activity is used to display the detail of the user profile.

activity_main.xml

  <?xml version=”1.0″ encoding=”utf-8″?>  <android.support.constraint.ConstraintLayout xmlns:android=”http://schemas.android.com/apk/res/android”      xmlns:app=”http://schemas.android.com/apk/res-auto”      xmlns:tools=”http://schemas.android.com/tools”      android:layout_width=”match_parent”      android:layout_height=”match_parent”      tools:context=”example.tutoraspire.com.kotlinvolleyregistrationloginsystem.MainActivity”>        <LinearLayout          android:layout_width=”match_parent”          android:layout_height=”fill_parent”          android:layout_marginBottom=”8dp”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”8dp”          android:orientation=”vertical”          app:layout_constraintBottom_toBottomOf=”parent”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintHorizontal_bias=”0.0″          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toTopOf=”parent”          app:layout_constraintVertical_bias=”0.0″>            <TextView              android:layout_width=”fill_parent”              android:layout_height=”wrap_content”              android:gravity=”center”              android:text=”Welcome to Profile”              android:textAppearance=”@style/Base.TextAppearance.AppCompat.Large” />            <TableLayout              android:layout_width=”match_parent”              android:layout_height=”wrap_content”              android:layout_marginTop=”50dp”>                  <TableRow>                    <TextView                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”Id”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Large” />                    <TextView                      android:id=”@+id/textViewId”                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”id”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Medium” />                </TableRow>                <TableRow>                    <TextView                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”Username”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Large” />                    <TextView                      android:id=”@+id/textViewUsername”                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”username”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Medium” />                </TableRow>                <TableRow>                    <TextView                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”Email”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Large” />                    <TextView                      android:id=”@+id/textViewEmail”                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”useremail”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Medium” />                </TableRow>                <TableRow>                    <TextView                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”Gender”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Large” />                    <TextView                      android:id=”@+id/textViewGender”                      android:layout_width=”wrap_content”                      android:layout_height=”wrap_content”                      android:padding=”10dp”                      android:text=”gender”                      android:textAppearance=”@style/Base.TextAppearance.AppCompat.Medium” />                </TableRow>              </TableLayout>            <Button              android:id=”@+id/buttonLogout”              android:layout_width=”210dp”              android:layout_height=”50dp”              android:layout_marginTop=”150dp”              android:layout_marginLeft=”75dp”              android:text=”Logout” />      </LinearLayout>    </android.support.constraint.ConstraintLayout>  

Now, create an activity_login.xml file in the layout directory with following code. This activity is used for user log-in UI.

activity_login.xml

  <?xml version=”1.0″ encoding=”utf-8″?>  <android.support.constraint.ConstraintLayout xmlns:android=”http://schemas.android.com/apk/res/android”      xmlns:app=”http://schemas.android.com/apk/res-auto”      xmlns:tools=”http://schemas.android.com/tools”      android:layout_width=”match_parent”      android:layout_height=”match_parent”      tools:context=”example.tutoraspire.com.kotlinvolleyregistrationloginsystem.LoginActivity”>        <TextView          android:layout_width=”fill_parent”          android:layout_height=”wrap_content”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”16dp”          android:gravity=”center”          android:text=”Login”          android:textAppearance=”@style/Base.TextAppearance.AppCompat.Large”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintHorizontal_bias=”1.0″          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toTopOf=”parent” />        <EditText          android:id=”@+id/etUserName”          android:layout_width=”fill_parent”          android:layout_height=”wrap_content”          android:layout_marginBottom=”8dp”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”8dp”          android:ems=”10″          android:inputType=”textPersonName”          android:hint=”user name”          app:layout_constraintBottom_toBottomOf=”parent”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintHorizontal_bias=”0.0″          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toTopOf=”parent”          app:layout_constraintVertical_bias=”0.144″ />        <EditText          android:id=”@+id/etUserPassword”          android:layout_width=”fill_parent”          android:layout_height=”wrap_content”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”8dp”          android:hint=”password”          android:ems=”10″          android:inputType=”textPassword”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toBottomOf=”@+id/etUserName” />        <Button          android:id=”@+id/btnLogin”          android:layout_width=”210dp”          android:layout_height=”50dp”          android:layout_marginBottom=”8dp”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”8dp”          android:text=”Login”          app:layout_constraintBottom_toBottomOf=”parent”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toBottomOf=”@+id/etUserName”          app:layout_constraintVertical_bias=”0.754″ />        <TextView          android:id=”@+id/tvRegister”          android:layout_width=”wrap_content”          android:layout_height=”wrap_content”          android:layout_marginBottom=”8dp”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”8dp”          android:gravity=”center”          android:text=”Create New Accountn Register Here”          app:layout_constraintBottom_toBottomOf=”parent”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toBottomOf=”@+id/btnLogin”          app:layout_constraintVertical_bias=”0.405″ />        <ProgressBar          android:id=”@+id/progressBar”          android:visibility=”gone”          style=”?android:attr/progressBarStyle”          android:layout_width=”wrap_content”          android:layout_height=”wrap_content”          android:layout_marginBottom=”8dp”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”8dp”          app:layout_constraintBottom_toBottomOf=”parent”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toTopOf=”parent”          app:layout_constraintVertical_bias=”0.456″ />    </android.support.constraint.ConstraintLayout>  

Create an activity_register.xml file in the layout directory with following code. This activity is used for user registration UI.

activity_register.xml

  <?xml version=”1.0″ encoding=”utf-8″?>  <android.support.constraint.ConstraintLayout xmlns:android=”http://schemas.android.com/apk/res/android”      xmlns:app=”http://schemas.android.com/apk/res-auto”      xmlns:tools=”http://schemas.android.com/tools”      android:layout_width=”match_parent”      android:layout_height=”match_parent”      tools:context=”example.tutoraspire.com.kotlinvolleyregistrationloginsystem.RegisterActivity”>          <LinearLayout          android:layout_width=”match_parent”          android:layout_height=”519dp”          android:layout_centerVertical=”true”          android:layout_marginBottom=”8dp”          android:layout_marginEnd=”8dp”          android:layout_marginStart=”8dp”          android:layout_marginTop=”8dp”          android:orientation=”vertical”          android:padding=”10dp”          app:layout_constraintBottom_toBottomOf=”parent”          app:layout_constraintEnd_toEndOf=”parent”          app:layout_constraintStart_toStartOf=”parent”          app:layout_constraintTop_toTopOf=”parent”          app:layout_constraintVertical_bias=”0.0″>            <TextView              android:layout_width=”fill_parent”              android:layout_height=”wrap_content”              android:text=”Register”              android:gravity=”center”              android:textAppearance=”@style/Base.TextAppearance.AppCompat.Large” />            <EditText              android:id=”@+id/editTextUsername”              android:layout_width=”match_parent”              android:layout_height=”wrap_content”              android:layout_marginBottom=”8dp”              android:layout_marginTop=”20dp”              android:hint=”Username”              android:inputType=”text” />            <EditText              android:id=”@+id/editTextEmail”              android:layout_width=”match_parent”              android:layout_height=”wrap_content”              android:layout_marginBottom=”8dp”              android:layout_marginTop=”8dp”              android:hint=”Email”              android:inputType=”textEmailAddress” />            <EditText              android:id=”@+id/editTextPassword”              android:layout_width=”match_parent”              android:layout_height=”wrap_content”              android:layout_marginBottom=”8dp”              android:layout_marginTop=”8dp”              android:fontFamily=”sans-serif”              android:hint=”Password”              android:inputType=”textPassword” />            <RadioGroup              android:id=”@+id/radioGender”              android:layout_width=”match_parent”              android:layout_height=”wrap_content”              android:layout_marginBottom=”8dp”              android:layout_marginTop=”8dp”              android:orientation=”horizontal”>                <RadioButton                  android:id=”@+id/radioButtonMale”                  android:layout_width=”wrap_content”                  android:layout_height=”wrap_content”                  android:checked=”true”                  android:text=”Male” />                  <RadioButton                  android:id=”@+id/radioButtonFemale”                  android:layout_width=”wrap_content”                  android:layout_height=”wrap_content”                  android:text=”Female” />            </RadioGroup>            <Button              android:id=”@+id/buttonRegister”              android:layout_width=”match_parent”              android:layout_height=”wrap_content”              android:layout_marginBottom=”8dp”              android:layout_marginTop=”90dp”              android:text=”Register” />            <TextView              android:id=”@+id/textViewLogin”              android:layout_width=”match_parent”              android:layout_height=”wrap_content”              android:layout_marginBottom=”8dp”              android:layout_marginTop=”8dp”              android:text=”Already Registered?nLogin Here”              android:textAlignment=”center”              android:textAppearance=”@style/Base.TextAppearance.AppCompat.Medium” />      </LinearLayout>        <ProgressBar          android:visibility=”gone”          android:id=”@+id/progressBar”          android:layout_width=”wrap_content”          android:layout_height=”wrap_content”          android:layout_centerHorizontal=”true”          android:layout_centerVertical=”true” />    </android.support.constraint.ConstraintLayout>  

Add the volley library dependency in build.gradle file.

build.gradle

  dependencies {      implementation fileTree(dir: ‘libs’, include: [‘*.jar’])      implementation “org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version”      implementation ‘com.android.support:appcompat-v7:26.1.0’      implementation ‘com.android.support.constraint:constraint-layout:1.1.3’      testImplementation ‘junit:junit:4.12’      implementation ‘com.android.volley:volley:1.0.0’  }  

Create a data model class named as User.kt with the following code.

User.kt

  package example.tutoraspire.com.kotlinvolleyregistrationloginsystem    class User(var id: Int, var name: String?, var email: String?, var gender: String?)  

We need to define our URL that calls the API of server-side.

Create an URLs.kt class and define the URL.

URLs.kt

  package example.tutoraspire.com.kotlinvolleyregistrationloginsystem    object URLs {      private val ROOT_URL = “http://192.168.1.35/androidphpmysql/registrationapi.php?apicall=”      val URL_REGISTER = ROOT_URL + “signup”      val URL_LOGIN = ROOT_URL + “login”  }  

VolleySingleton.kt

  package example.tutoraspire.com.kotlinvolleyregistrationloginsystem    import android.content.Context  import com.android.volley.Request  import com.android.volley.RequestQueue  import com.android.volley.toolbox.Volley    class VolleySingleton private constructor(context: Context) {      private var mRequestQueue: RequestQueue        // applicationContext is key, it keeps you from leaking the      // Activity or BroadcastReceiver if someone passes one in.      val requestQueue: RequestQueue          get() {              if (mRequestQueue == null) {                  mRequestQueue = Volley.newRequestQueue(mCtx?.applicationContext)              }              return mRequestQueue          }        init {          mCtx = context          mRequestQueue = requestQueue      }        fun <T> addToRequestQueue(req: Request<T>) {          requestQueue.add(req)      }        companion object {          private var mInstance: VolleySingleton? = null          private var mCtx: Context? = null            @Synchronized          fun getInstance(context: Context): VolleySingleton {              if (mInstance == null) {                  mInstance = VolleySingleton(context)              }              return mInstance as VolleySingleton          }      }  }  

Create a class named as SharedPreferences.kt. In this class, we use the SharedPreferences class to store the user detail. The SharedPreferences class contains four methods with the following functionalities:

userLogin(): This function is used to store the user information in SharedPreferences after log-in.
isLoggedIn: This method checks whether the user is already log-in or not.
user: User get(): This method gets the user information if log-in.
logout(): This function clears the SharedPreferences data and makes user log-out.

SharedPrefManager.kt

  package example.tutoraspire.com.kotlinvolleyregistrationloginsystem    import android.content.Context  import android.content.Intent    class SharedPrefManager private constructor(context: Context) {        //this method will checker whether user is already logged in or not      val isLoggedIn: Boolean          get() {              val sharedPreferences = ctx?.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)              return sharedPreferences?.getString(KEY_USERNAME, null) != null          }        //this method will give the logged in user      val user: User          get() {              val sharedPreferences = ctx?.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)              return User(                      sharedPreferences!!.getInt(KEY_ID, -1),                      sharedPreferences.getString(KEY_USERNAME, null),                      sharedPreferences.getString(KEY_EMAIL, null),                      sharedPreferences.getString(KEY_GENDER, null)              )          }        init {          ctx = context      }        //this method will store the user data in shared preferences      fun userLogin(user: User) {          val sharedPreferences = ctx?.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)          val editor = sharedPreferences?.edit()          editor?.putInt(KEY_ID, user.id)          editor?.putString(KEY_USERNAME, user.name)          editor?.putString(KEY_EMAIL, user.email)          editor?.putString(KEY_GENDER, user.gender)          editor?.apply()      }        //this method will logout the user      fun logout() {          val sharedPreferences = ctx?.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)          val editor = sharedPreferences?.edit()          editor?.clear()          editor?.apply()          ctx?.startActivity(Intent(ctx, LoginActivity::class.java))      }        companion object {            private val SHARED_PREF_NAME = “volleyregisterlogin”          private val KEY_USERNAME = “keyusername”          private val KEY_EMAIL = “keyemail”          private val KEY_GENDER = “keygender”          private val KEY_ID = “keyid”          private var mInstance: SharedPrefManager? = null          private var ctx: Context? = null          @Synchronized          fun getInstance(context: Context): SharedPrefManager {              if (mInstance == null) {                  mInstance = SharedPrefManager(context)              }              return mInstance as SharedPrefManager          }      }  }  

Now, in the MainActivity.kt class, we will display the user information if the user is logged-in otherwise, it redirects to LoginActivity.kt class. The onClick() method is used to log-out the user when clicking on the button.

MainActivity.kt

  package example.tutoraspire.com.kotlinvolleyregistrationloginsystem    import android.support.v7.app.AppCompatActivity  import android.os.Bundle  import android.content.Intent  import android.view.View  import android.widget.Button  import android.widget.TextView    class MainActivity : AppCompatActivity(), View.OnClickListener {        internal lateinit var id: TextView      internal lateinit var userName: TextView      internal lateinit var userEmail: TextView      internal lateinit var gender: TextView      internal lateinit var btnLogout: Button      override fun onCreate(savedInstanceState: Bundle?) {          super.onCreate(savedInstanceState)          setContentView(R.layout.activity_main)          if (SharedPrefManager.getInstance(this).isLoggedIn) {              id = findViewById(R.id.textViewId)              userName = findViewById(R.id.textViewUsername)              userEmail = findViewById(R.id.textViewEmail)              gender = findViewById(R.id.textViewGender)              btnLogout = findViewById(R.id.buttonLogout)                val user = SharedPrefManager.getInstance(this).user                id.text = user.id.toString()              userEmail.text = user.email              gender.text = user.gender              userName.text = user.name                btnLogout.setOnClickListener(this)            } else {              val intent = Intent(this@MainActivity, LoginActivity::class.java)              startActivity(intent)              finish()          }      }        override fun onClick(view: View) {          if (view == btnLogout) {              SharedPrefManager.getInstance(applicationContext).logout()          }      }  }  

In the LoginActivity.kt class, we check that the user is already logged-in or not, if true then redirect to MainActivity.kt class otherwise, allow a user to log-in.

StringRequest class of Volley library is used for network module. The object of StringRequest class takes the parameters of the type request method, URL, and the response.

LoginActivity.kt

  package example.tutoraspire.com.kotlinvolleyregistrationloginsystem    import android.support.v7.app.AppCompatActivity  import android.os.Bundle    import android.content.Intent  import android.text.TextUtils  import android.view.View  import android.widget.EditText  import android.widget.ProgressBar  import android.widget.Toast  import com.android.volley.AuthFailureError  import com.android.volley.Request  import com.android.volley.Response  import com.android.volley.toolbox.StringRequest  import kotlinx.android.synthetic.main.activity_login.*  import org.json.JSONException  import org.json.JSONObject  import java.util.HashMap    class LoginActivity : AppCompatActivity() {      internal lateinit var etName: EditText      internal lateinit var etPassword: EditText      internal lateinit var progressBar: ProgressBar      override fun onCreate(savedInstanceState: Bundle?) {          super.onCreate(savedInstanceState)          setContentView(R.layout.activity_login)            if (SharedPrefManager.getInstance(this).isLoggedIn) {              finish()              startActivity(Intent(this, MainActivity::class.java))          }            progressBar = findViewById(R.id.progressBar)          etName = findViewById(R.id.etUserName)          etPassword = findViewById(R.id.etUserPassword)            //calling the method userLogin() for login the user           btnLogin.setOnClickListener(View.OnClickListener {              userLogin()          })            //if user presses on textview it call the activity RegisterActivity          tvRegister.setOnClickListener(View.OnClickListener {              finish()              startActivity(Intent(applicationContext, RegisterActivity::class.java))          })      }        private fun userLogin() {          //first getting the values          val username = etName.text.toString()          val password = etPassword.text.toString()          //validating inputs          if (TextUtils.isEmpty(username)) {              etName.error = “Please enter your username”              etName.requestFocus()              return          }            if (TextUtils.isEmpty(password)) {              etPassword.error = “Please enter your password”              etPassword.requestFocus()              return          }            //if everything is fine          val stringRequest = object : StringRequest(Request.Method.POST, URLs.URL_LOGIN,                  Response.Listener { response ->                      progressBar.visibility = View.GONE                        try {                          //converting response to json object                          val obj = JSONObject(response)                            //if no error in response                          if (!obj.getBoolean(“error”)) {                              Toast.makeText(applicationContext, obj.getString(“message”), Toast.LENGTH_SHORT).show()                                //getting the user from the response                              val userJson = obj.getJSONObject(“user”)                                //creating a new user object                              val user = User(                                      userJson.getInt(“id”),                                      userJson.getString(“username”),                                      userJson.getString(“email”),                                      userJson.getString(“gender”)                              )                                //storing the user in shared preferences                              SharedPrefManager.getInstance(applicationContext).userLogin(user)                              //starting the MainActivity                              finish()                              startActivity(Intent(applicationContext, MainActivity::class.java))                          } else {                              Toast.makeText(applicationContext, obj.getString(“message”), Toast.LENGTH_SHORT).show()                          }                      } catch (e: JSONException) {                          e.printStackTrace()                      }                  },                  Response.ErrorListener { error -> Toast.makeText(applicationContext, error.message, Toast.LENGTH_SHORT).show() }) {              @Throws(AuthFailureError::class)              override fun getParams(): Map<String, String> {                  val params = HashMap<String, String>()                  params[“username”] = username                  params[“password”] = password                  return params              }          }            VolleySingleton.getInstance(this).addToRequestQueue(stringRequest)      }  }  

The RegisterActivity.kt class is used to register the user. This class initially checks the user log-in, if true then redirect to MainActivity.kt class otherwise, allow user for registration.

Similar to LoginActivity.kt class, we use the StringRequest class of Volley library for network connection and pass the parameters of the type request method, URL, and the response. The Response.Listener handles the response generated by the server.

RegisterActivity.kt

  package example.tutoraspire.com.kotlinvolleyregistrationloginsystem    import android.support.v7.app.AppCompatActivity  import android.os.Bundle  import android.content.Intent  import android.text.TextUtils  import android.view.View  import android.widget.EditText  import android.widget.ProgressBar  import android.widget.RadioButton  import android.widget.RadioGroup  import android.widget.Toast  import com.android.volley.AuthFailureError  import com.android.volley.Request  import com.android.volley.Response  import com.android.volley.toolbox.StringRequest  import kotlinx.android.synthetic.main.activity_register.*  import org.json.JSONException  import org.json.JSONObject  import java.util.HashMap    class RegisterActivity : AppCompatActivity() {      internal lateinit var editTextUsername: EditText      internal lateinit var editTextEmail: EditText      internal lateinit var editTextPassword: EditText      internal lateinit var radioGroupGender: RadioGroup      internal lateinit var progressBar: ProgressBar      override fun onCreate(savedInstanceState: Bundle?) {          super.onCreate(savedInstanceState)          setContentView(R.layout.activity_register)          progressBar = findViewById(R.id.progressBar)            //if the user is already logged in we will directly start the MainActivity (profile) activity          if (SharedPrefManager.getInstance(this).isLoggedIn) {              finish()              startActivity(Intent(this, MainActivity::class.java))              return          }            editTextUsername = findViewById(R.id.editTextUsername)          editTextEmail = findViewById(R.id.editTextEmail)          editTextPassword = findViewById(R.id.editTextPassword)          radioGroupGender = findViewById(R.id.radioGender)            buttonRegister.setOnClickListener(View.OnClickListener {              //if user pressed on button register              //here we will register the user to server              registerUser()          })            textViewLogin.setOnClickListener(View.OnClickListener {              finish()              startActivity(Intent(this@RegisterActivity, LoginActivity::class.java))          })      }        private fun registerUser() {          val username = editTextUsername.text.toString().trim { it <= ‘ ‘ }          val email = editTextEmail.text.toString().trim { it <= ‘ ‘ }          val password = editTextPassword.text.toString().trim { it <= ‘ ‘ }            val gender = (findViewById<View>(radioGroupGender.checkedRadioButtonId) as RadioButton).text.toString()            //first we will do the validations          if (TextUtils.isEmpty(username)) {              editTextUsername.error = “Please enter username”              editTextUsername.requestFocus()              return          }            if (TextUtils.isEmpty(email)) {              editTextEmail.error = “Please enter your email”              editTextEmail.requestFocus()              return          }            if (!android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches()) {              editTextEmail.error = “Enter a valid email”              editTextEmail.requestFocus()              return          }            if (TextUtils.isEmpty(password)) {              editTextPassword.error = “Enter a password”              editTextPassword.requestFocus()              return          }            val stringRequest = object : StringRequest(Request.Method.POST, URLs.URL_REGISTER,                  Response.Listener { response ->                      progressBar.visibility = View.GONE                        try {                          //converting response to json object                          val obj = JSONObject(response)                          //if no error in response                          if (!obj.getBoolean(“error”)) {                              Toast.makeText(applicationContext, obj.getString(“message”), Toast.LENGTH_SHORT).show()                                //getting the user from the response                              val userJson = obj.getJSONObject(“user”)                                //creating a new user object                              val user = User(                                      userJson.getInt(“id”),                                      userJson.getString(“username”),                                      userJson.getString(“email”),                                      userJson.getString(“gender”)                              )                                //storing the user in shared preferences                              SharedPrefManager.getInstance(applicationContext).userLogin(user)                                //starting the MainActivity activity                              finish()                              startActivity(Intent(applicationContext, MainActivity::class.java))                          } else {                              Toast.makeText(applicationContext, obj.getString(“message”), Toast.LENGTH_SHORT).show()                          }                      } catch (e: JSONException) {                          e.printStackTrace()                      }                  },                  Response.ErrorListener { error -> Toast.makeText(applicationContext, error.message, Toast.LENGTH_SHORT).show() }) {              @Throws(AuthFailureError::class)              override fun getParams(): Map<String, String> {                  val params = HashMap<String, String>()                  params[“username”] = username                  params[“email”] = email                  params[“password”] = password                  params[“gender”] = gender                  return params              }          }            VolleySingleton.getInstance(this).addToRequestQueue(stringRequest)      }  }  

AndroidManifest.xml

Add the following permission in AndroidManifest.xml file

  <uses-permission android:name=”android.permission.ACCESS_NETWORK_STATE” />  <uses-permission android:name=”android.permission.INTERNET” />  

Note: The server side code of registration and login are implemented in PHP with MySQL at https://tutoraspire.com/android-volley-library-registration-login-logout.

Output:

Kotlin Android Web Service

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