Android SharedPreferences – Save Key Value​ data example in kotlin

Android SharedPreferences is store key-value (String, Integer, Boolean, etc) Paris data. SharedPreferences object points to a file holding a key-value pair and provides simple methods to read and write data. It can be private or shared.

SharedPreferences usually use to save a setting preference (push notification, alert, the default setting of the app, etc) or manage a login session in the app.

In this tutorial, you will learn the following:

1. What is Android SharedPreferences and how to create it.
2. Saving and Retrieving data in SharedPreferences in Kotlin.

Create Shared Preferences

For a creating or accessing an existing shared preference, you can use by calling one of a method:

• getSharedPreferences() – this method used for multiple shared preference files and it can be identified by name. For call, this has to use any Context of your app.
• getPreferences() – Retrieve a default shared preferences file from the Activity (belong to the activity). It uses only one shared preference file for the activity.

getSharedPreferences()

When naming your shared preference files, you should use a name that’s uniquely identifiable to your app. An easy way to do this is to prefix the file name with your application ID. For example: "com.example.myapp.PREFERENCE_FILE_KEY"

val sharedPref = activity?.getSharedPreferences(
        getString(R.string.preference_file_key), Context.MODE_PRIVATE)

getPreferences()

if you need just one shared preference file for your activity.

val sharedPref = activity?.getPreferences(Context.MODE_PRIVATE)

Note: The MODE_WORLD_READABLE and MODE_WORLD_WRITEABLE modes have been deprecated since API level 17.

Write to shared preferences

You have call edit() on yourSharedPreferences, To write to a shared preferences file.

val sharedPref = this.getPreferences(Context.MODE_PRIVATE) ?: return
        with(sharedPref.edit()) {
            putString("name", et_name.text.toString())
            commit()
        }

Pass the keys and values you want to write with methods for example :  putInt() and putString(). Then call apply() orcommit() to save the changes. For example:

Check this tutorial question number #2 :  What is the difference between commit() and apply() method in SharedPreferences()?

Read from shared preferences

val sharedPref = this.getPreferences(Context.MODE_PRIVATE) ?: return
        val str_name = sharedPref.getString("name", "")

To retrieve values from a shared preferences file, call methods getInt() and getString() etc, providing the key for the value you want, and optionally a default value to return if the key isn’t present. For example:

Let’s Build a Simple Example of Android SharedPreferences

Step 1. Create new project “Build Your First Android App in Kotlin“

Step 2. Add following code in “activity_main.xml” layout file

adding 2 TextView and 2 Button. Where button have method to perform a Click action.

<?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=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Enter Details"
        android:textSize="16dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/et_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:hint="Name"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView" />

    <EditText
        android:id="@+id/et_number"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:ems="10"
        android:hint="Number"
        android:inputType="phone"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/et_name" />

    <Button
        android:id="@+id/btn_save"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="32dp"
        android:text="Save"
        android:onClick="saveData"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/et_number" />

    <Button
        android:id="@+id/btn_get"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginTop="32dp"
        android:text="Get"
        android:onClick="getData"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/et_number" />

</android.support.constraint.ConstraintLayout>

Step 3. Open the “MainActivity.kt” and add following code

In this code doing action by clicking button. Saving and getting data with same key.

package `in`.eyehunt.sharedpreferences

import android.content.Context
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

    //saving data
    fun saveData(view: View) {
        val sharedPref = this.getPreferences(Context.MODE_PRIVATE) ?: return
        with(sharedPref.edit()) {
            putString("name", et_name.text.toString())
            putInt("number", et_number.text.toString().toInt())
            commit()
        }
    }

    fun getData(view: View) {
        val sharedPref = this.getPreferences(Context.MODE_PRIVATE) ?: return
        val str_name = sharedPref.getString("name", "")
        val int_number = sharedPref.getInt("number", 0)
        Toast.makeText(this, "$str_name $int_number", Toast.LENGTH_LONG).show()

    }
}

Step 4. Now Run the application, in emulator or On you android device

Output screenshot Android SharedPreferences example :

Download source code Android SharedPreferences in kotlin

https://github.com/EyeHunts/SharedPreferences

Note: This example (Project) is developed in Android Studio 3.1.3. Tested on Android 9 ( Android-P), compile SDK version API 27: Android 8.0 (Oreo)

MinSdkVersion=”15″

TargetSdkVersion=”27″

Coding in Kotlin