Login - SignUp & LogOut Example using Shared Preferences - Android Studio

In this example, I will show you how to maintain user login session.The user login session will be maintained in an app even if the app is closed. The user will always be in a logged in state until he logouts. We will stored data into Shared Preferences.

Example Video:-

Android studio project screen.

Step.1

MainActivity.kt

Add the following code in the MainActivity.kt class.

package com.study.kotlinkatta
import android.content.Context
import android.content.Intent
import android.os.Bundle
import android.view.Gravity
import android.view.LayoutInflater
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.PopupWindow
import android.widget.Toast
import androidx.appcompat.app.ActionBar
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.sign_up_window.view.*

class MainActivity : AppCompatActivity() {

    var sharedPreference:SharedPreference? = null
    lateinit var edt_email: EditText
    lateinit var edt_password: EditText
    lateinit var btn_login: Button
    lateinit var btn_sign_up: Button

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        sharedPreference =SharedPreference(this)
        edt_email = findViewById(R.id.edt_email)
        edt_password = findViewById(R.id.edt_password)
        btn_login = findViewById(R.id.btn_login)
        btn_sign_up = findViewById(R.id.btn_sign_up)

        val str_login_status = sharedPreference!!.getPreferenceString("login_status")
        if (str_login_status!=null){
            val intent = Intent(this, DashboardActivity::class.java)
            startActivity(intent)
            finish()
        }

        btn_login.setOnClickListener {
            val str_email_id = edt_email.text.toString()
            val str_password = edt_password.text.toString()

            if(str_email_id.equals("") || str_password.equals("")){
                Toast.makeText(this,"Please Enter Details.",Toast.LENGTH_SHORT).show()
            }else {
                val email_id = sharedPreference!!.getPreferenceString("email_id")
                val password = sharedPreference!!.getPreferenceString("password")

                if(email_id.equals(str_email_id) && password.equals(str_password)){
                    sharedPreference!!.save_String("login_status","1")

                    val intent = Intent(this, DashboardActivity::class.java)
                    startActivity(intent)
                    finish()
                }else {
                    Toast.makeText(this,"User Not Available.",Toast.LENGTH_SHORT).show()
                }
            }
        }

        btn_sign_up.setOnClickListener {
            fun_SignUp_PopupWindow()
        }
    }
    private fun fun_SignUp_PopupWindow() {
        val layoutInflater = this.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
        val popView: View = layoutInflater.inflate(R.layout.sign_up_window, null)
        val popupWindow: PopupWindow
        popupWindow = PopupWindow(popView, ActionBar.LayoutParams.MATCH_PARENT, ActionBar.LayoutParams.MATCH_PARENT,true)
        popupWindow.showAtLocation(popView, Gravity.CENTER, 0, 0)

        val btn_dia_submit = popView.findViewById(R.id.btn_dia_submit) as Button
        btn_dia_submit.setOnClickListener {

            val str_dia_email_id = popView.edt_dia_email_id.text.toString()
            val str_dia_password = popView.edt_dia_password.text.toString()

            if(str_dia_email_id.equals("") || str_dia_password.equals("")){
                Toast.makeText(this,"Please Enter Details.",Toast.LENGTH_SHORT).show()
            }else {
                popupWindow.dismiss()
                sharedPreference!!.save_String("email_id",str_dia_email_id)
                sharedPreference!!.save_String("password",str_dia_password)
                Toast.makeText(this,"Data Saved Successfully.",Toast.LENGTH_SHORT).show()
            }
        }
    }

}

Step.2

activity_main.xml

Add the following code in the activity_main.xml file.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    android:layout_margin="15dp"
    tools:context=".MainActivity">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Login"
            android:textSize="40dp"
            android:fontFamily="sans-serif-black"
            android:gravity="center"
            android:layout_marginTop="10dp"
            android:layout_marginBottom="30dp"/>

        <EditText
            android:id="@+id/edt_email"
            android:hint="Enter Email Id"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="5dp"
            android:layout_margin="5dp"
            android:background="#E7E7E7"/>

        <EditText
            android:id="@+id/edt_password"
            android:hint="Enter Password"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="5dp"
            android:layout_margin="5dp"
            android:background="#E7E7E7"/>

        <Button
            android:layout_marginTop="10dp"
            android:id="@+id/btn_login"
            android:text="Login"
            android:textAllCaps="false"
            android:background="@color/colorAccent"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <Button
            android:layout_marginTop="10dp"
            android:id="@+id/btn_sign_up"
            android:textAllCaps="false"
            android:text="Sign Up"
            android:background="@color/colorAccent"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

</LinearLayout>

Step.3

sign_up_window.xml

Add the following code in the sign_up_window.xml.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/popup_element"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#9999"
    android:layout_gravity="center"
    android:gravity="center"
    android:orientation="vertical">

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_margin="10dp"
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:background="#757575">

            <TextView
                android:layout_margin="10dp"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Sign Up"
                android:textColor="#FFF"
                android:textSize="25dp"
                android:gravity="center"/>

            <EditText
                android:id="@+id/edt_dia_email_id"
                android:hint="Enter Email Id"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:padding="5dp"
                android:layout_margin="5dp"
                android:background="#E7E7E7"/>

            <EditText
                android:id="@+id/edt_dia_password"
                android:hint="Enter Password"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:padding="5dp"
                android:layout_margin="5dp"
                android:background="#E7E7E7"/>

                <Button
                    android:id="@+id/btn_dia_submit"
                    android:layout_margin="5dp"
                    android:layout_weight="1"
                    android:text="Submit"
                    android:textAllCaps="false"
                    android:background="@color/colorAccent"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content" />

           </LinearLayout>
    </ScrollView>
</LinearLayout>

Step.4

SharedPreference.kt

Add the following code in the SharedPreference.kt class.

package com.study.kotlinkatta
import android.content.Context
import android.content.SharedPreferences

class SharedPreference (val context: Context) {
    private val preference_Name = "Kotlinkatta"
    val shared_Pref: SharedPreferences = context.getSharedPreferences(preference_Name, Context.MODE_PRIVATE)

    /*Stored String Data*/
    fun save_String(key_name: String, text: String) {
        val editor: SharedPreferences.Editor = shared_Pref.edit()
        editor.putString(key_name, text)
        editor.commit()
    }

    fun getPreferenceString(key_name: String): String? {
        return shared_Pref.getString(key_name, null)
    }

    fun clearSharedPreference() {
        val editor: SharedPreferences.Editor = shared_Pref.edit()
        editor.clear()
        editor.commit()
    }
}

Step.5

DashboardActivity.kt

Add the following code in the DashboardActivity.kt class.

package com.study.kotlinkatta
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.Toast

class DashboardActivity : AppCompatActivity() {
    var sharedPreference:SharedPreference? = null
    lateinit var btn_log_out: Button

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_dashboard)
        sharedPreference =SharedPreference(this)

        btn_log_out = findViewById(R.id.btn_log_out)
        btn_log_out.setOnClickListener {

            sharedPreference!!.clearSharedPreference()
            Toast.makeText(this,"User LogOut Successfully.",Toast.LENGTH_SHORT).show()

            val intent = Intent(this, MainActivity::class.java)
            startActivity(intent)
            finish()
        }
    }
}