How to use shared preferences in Android using Kotlin?

This example demonstrates how to use shared preferences in Android using Kotlin.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
   <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context=".MainActivity">
   <TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="50dp"
      android:text="Tutorials Point"
      android:textAlignment="center"
      android:textColor="@android:color/holo_green_dark"
      android:textSize="32sp"
      android:textStyle="bold" />
   <EditText
      android:id="@+id/etName"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@+id/textView"
      android:layout_centerInParent="true"
      android:layout_marginTop="75dp"
      android:ems="10"
      android:hint="Enter Name" />
   <EditText
      android:id="@+id/etPassword"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@id/etName"
      android:layout_centerHorizontal="true"
      android:ems="10"
      android:hint="Enter Password" />
   <Button
      android:id="@+id/btnLogin"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@id/etPassword"
      android:layout_alignStart="@id/etPassword"
      android:layout_marginTop="10dp"
      android:text="Login" />
   <CheckBox
      android:id="@+id/checkBox"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@id/btnLogin"
      android:layout_alignStart="@id/btnLogin"
      android:layout_marginTop="10dp"
   android:text="Remember my credentials" />
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.content.SharedPreferences
import android.os.Bundle
import android.preference.PreferenceManager
import android.widget.Button
import android.widget.CheckBox
import android.widget.EditText
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   private lateinit var sharedPreferences: SharedPreferences
   private lateinit var editor: SharedPreferences.Editor
   private lateinit var name: EditText
   private lateinit var password: EditText
   private lateinit var button: Button
   private lateinit var checkBox: CheckBox
   private lateinit var strName: String
   private lateinit var strPassword: String
   private lateinit var strCheckBox: String
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      name = findViewById(R.id.etName)
      password = findViewById(R.id.etPassword)
      button = findViewById(R.id.btnLogin)
      checkBox = findViewById(R.id.checkBox)
      sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this)
      editor = sharedPreferences.edit()
      checkSharedPreference()
      button.setOnClickListener {
         if (checkBox.isChecked) {
            editor.putString(getString(R.string.checkBox), "True")
            editor.apply()
            strName = name.text.toString()
            editor.putString(getString(R.string.name), strName)
            editor.commit()
            strPassword = password.text.toString()
            editor.putString(getString(R.string.password), strPassword)
            editor.commit()
         } else {
            editor.putString(getString(R.string.checkBox), "False")
            editor.commit()
            editor.putString(getString(R.string.name), "")
            editor.commit()
            editor.putString(getString(R.string.password), "")
            editor.commit()
         }
      }
   }
   private fun checkSharedPreference() {
      strCheckBox = sharedPreferences.getString(getString(R.string.checkBox), "False").toString()
      strName = sharedPreferences.getString(getString(R.string.name), "").toString()
      strPassword = sharedPreferences.getString(getString(R.string.password), "").toString()
      name.setText(strName)
      password.setText(strPassword)
      checkBox.isChecked = strCheckBox == "True"
   }
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.q11">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen