Preferences DataStore in Android

Last Updated : 24 Jan, 2021

Preference Data Store is used to store data permanently in android. Earlier we had to Shared Preferences for the same but since it is deprecated we are using Data Store now. A sample video is given below to get an idea about what we are going to do in this article. Note that we are going to implement this project using the Kotlin language.

Step by Step Implementation

Step 1: Create a new project

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Kotlin as the programming language

Step 2: Add dependency inside build.gradle(app)

Add the Data Store, Lifecycle, and Coroutines dependency inside the build.gradle(app) and click on the sync now button.

// Preferences DataStore

implementation “androidx.datastore:datastore-preferences:1.0.0-alpha01”

// Lifecycle components

implementation “androidx.lifecycle:lifecycle-livedata-ktx:2.2.0”

implementation “androidx.lifecycle:lifecycle-extensions:2.2.0”

implementation “androidx.lifecycle:lifecycle-common-java8:2.2.0”

implementation “androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0”

// Kotlin coroutines components

implementation “org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.4.10”

api “org.jetbrains.kotlinx:kotlinx-coroutines-core:1.4.1”

api “org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.1”

Step 3: Working with the activity_main.xml file

Go to the activity_main.xml file and refer to the following code. Below is the code for the activity_main.xml file. This is for the basic layout used in the app.

XML

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
    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"
    android:gravity="center_horizontal"
    android:orientation="vertical"
    tools:context=".MainActivity"> 
  
    <EditText
        android:id="@+id/et_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:layout_marginTop="20dp"
        android:ems="10"
        android:hint="Name" /> 
  
    <EditText
        android:id="@+id/et_age"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:ems="10"
        android:hint="Age"
        android:inputType="number" /> 
  
    <Button
        android:id="@+id/btn_save"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:background="#FF7043"
        android:padding="10dp"
        android:text="Save user"
        android:textColor="@android:color/white" /> 
  
    <TextView
        android:id="@+id/tv_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:text="Name"
        android:textColor="@android:color/black"
        android:textSize="20sp" /> 
  
    <TextView
        android:id="@+id/tv_age"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:text="Age"
        android:textColor="@android:color/black"
        android:textSize="20sp" /> 
  
</LinearLayout>

Step 4: Working with the UserManager.kt class

Create a new kotlin class and name it UserManager, this class holds the code for saving and retrieving data from the preference Data Store. Comments are added inside the code to understand the code in more detail.

Kotlin

import android.content.Context 
import androidx.datastore.preferences.createDataStore 
import androidx.datastore.preferences.edit 
import androidx.datastore.preferences.preferencesKey 
import kotlinx.coroutines.flow.Flow 
import kotlinx.coroutines.flow.map 
  
class UserManager(context: Context) { 
  
    // Create the dataStore and give it a name same as shared preferences 
    private val dataStore = context.createDataStore(name = "user_prefs") 
  
    // Create some keys we will use them to store and retrieve the data 
    companion object { 
        val USER_AGE_KEY = preferencesKey<Int>("USER_AGE") 
        val USER_NAME_KEY = preferencesKey<String>("USER_NAME") 
    } 
  
    // Store user data 
    // refer to the data store and using edit  
    // we can store values using the keys 
    suspend fun storeUser(age: Int, name: String) { 
        dataStore.edit { 
            it[USER_AGE_KEY] = age 
            it[USER_NAME_KEY] = name 
  
            // here it refers to the preferences we are editing 
  
        } 
    } 
  
    // Create an age flow to retrieve age from the preferences 
    // flow comes from the kotlin coroutine 
    val userAgeFlow: Flow<Int> = dataStore.data.map { 
        it[USER_AGE_KEY] ?: 0
    } 
  
    // Create a name flow to retrieve name from the preferences 
    val userNameFlow: Flow<String> = dataStore.data.map { 
        it[USER_NAME_KEY] ?: ""
    } 
}

Step 5: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

Kotlin

import android.os.Bundle 
import android.widget.Button 
import android.widget.EditText 
import android.widget.TextView 
import androidx.appcompat.app.AppCompatActivity 
import androidx.lifecycle.asLiveData 
import androidx.lifecycle.observe 
import kotlinx.coroutines.GlobalScope 
import kotlinx.coroutines.launch 
  
class MainActivity : AppCompatActivity() { 
  
    lateinit var etName: EditText 
    lateinit var etAge: EditText 
    lateinit var tvName: TextView 
    lateinit var tvAge: TextView 
    lateinit var saveButton: Button 
  
    lateinit var userManager: UserManager 
    var age = 0
    var name = ""
  
    override fun onCreate(savedInstanceState: Bundle?) { 
        super.onCreate(savedInstanceState) 
        setContentView(R.layout.activity_main) 
  
        etName = findViewById(R.id.et_name) 
        etAge = findViewById(R.id.et_age) 
        tvName = findViewById(R.id.tv_name) 
        tvAge = findViewById(R.id.tv_age) 
        saveButton = findViewById(R.id.btn_save) 
  
        // Get reference to our userManager class 
        userManager = UserManager(this) 
  
        // this function saves the data to 
        // preference data store on click of 
        // save Button 
        buttonSave() 
  
        // this function retrieves the saved data 
        // as soon as they are stored and even 
        // after app is closed and started again 
        observeData() 
    } 
  
    private fun buttonSave() { 
        // Gets the user input and saves it 
        saveButton.setOnClickListener { 
            name = etName.text.toString() 
            age = etAge.text.toString().toInt() 
  
            // Stores the values 
            // Since the storeUser function of UserManager 
            // class is a suspend function 
            // So this has to be done in a coroutine scope 
            GlobalScope.launch { 
                userManager.storeUser(age, name) 
            } 
        } 
    } 
  
    private fun observeData() { 
        // Updates age 
        // every time user age changes it will be observed by userAgeFlow 
        // here it refers to the value returned from the userAgeFlow function  
        // of UserManager class 
        this.userManager.userAgeFlow.asLiveData().observe(this) { 
            age = it 
            tvAge.text = it.toString() 
        } 
  
        // Updates name 
        // every time user name changes it will be observed by userNameFlow 
        // here it refers to the value returned from the usernameFlow function  
        // of UserManager class 
        userManager.userNameFlow.asLiveData().observe(this) { 
            name = it 
            tvName.text = it.toString() 
        } 
    } 
}

Output:

Github repo here.

Suggest improvement

How to Save ArrayList to SharedPreferences in Android?

How to Add Views Dynamically and Store Data in Arraylist in Android?

Share your thoughts in the comments

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Basics

Software Setup and Configuration

File Structure & Components

Core Topics

Layout & View

Button

Intent and Intent Filters

Toast & RecyclerView

Fragments & Adapters

UI Component & Image Loading Libraries

Date and Time

Material Design & Bars

Working with Google Maps

Chart & Animation

Database

Advance Android

Jetpack & Architecture

App Publish & App Monetization

Projects

Basics

Software Setup and Configuration

File Structure & Components

Core Topics

Layout & View

Button

Intent and Intent Filters

Toast & RecyclerView

Fragments & Adapters

UI Component & Image Loading Libraries

Date and Time

Material Design & Bars

Working with Google Maps

Chart & Animation

Database

Advance Android

Jetpack & Architecture

App Publish & App Monetization

Projects

Preferences DataStore in Android

Step by Step Implementation

XML

Kotlin

Kotlin

Output:

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