Retrieving Value using Shared Preference in Kotlin

Question

I am trying to pass a value between two activities in kotlin but if I used the below code then I am getting only "Hello World" default value and not the PREFERENCE_NAME value. My text id name is android:id="@+id/tv_count" Any help is appreciated.

Main Activity:
import android.content.Context
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

        val mypreference=MyPreference(this)
        var loginCount=mypreference.getLoginName()
        mypreference.setLoginName(loginCount)
        tv_count.text=loginCount.toString()
    }
}

My Preference:
import android.content.Context

class MyPreference(context:Context)
{

    val PREFERENCE_NAME="SharedPreferenceExample"
    val preference=context.getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE)

    fun getLoginName():String
    {
        return preference.getString(PREFERENCE_NAME,"Hello World")
    }

    fun setLoginName(name:String)
    {
        val editor=preference.edit()
        editor.putString(PREFERENCE_NAME,name)
    }
}

In kotlin we can use different approach. Look here for more details: https://stackoverflow.com/a/56873719/3710341 — Sagar Chapagain, Jul 04 '19 at 14:33

score 13 · Answer 1 · answered Dec 27 '18 at 10:02

In your case, you have not used editor.commit() function. Here is the whole code

//Store in SharedPreference  
 val preference=getSharedPreferences(resources.getString(R.string.app_name), Context.MODE_PRIVATE)
    val editor=preference.edit()
    editor.putBoolean("isLoggedIn",true)
    editor.putInt("id",1)
    editor.putString("name","Alex")
    editor.commit()


//Retrieve from SharedPreference

    val name= preference.getString("name","")
    val id= preference.getInt("id",0)
    val isLoggedIn= preference.getBoolean("isLoggedIn",false)

score 3 · Accepted Answer · answered Oct 21 '18 at 19:48

3

You need to call commit i.e.

fun setLoginName(name:String)
{
    val editor=preference.edit()
    editor.putString(PREFERENCE_NAME,name)
    editor.commit()
}

answered Oct 21 '18 at 19:48

John O'Reilly

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Thanks John O'Reily for your response. Still I am seeing Hello World in the screen – Oct 21 '18 at 20:05

Gábor · Answer 3 · 2019-06-27T12:59:28.733

This one will be a broader answer showing a general way of using preferences very elegantly, thanks to the delegated properties in Kotlin. These allow us to provide our own backing store to everyday properties.

Consider this class that describes how to read and write a boolean:

class BooleanPrefStore(val default: Boolean = false) {
  operator fun getValue(thisRef: ContextWrapper?, property: KProperty<*>): Boolean =
    PreferenceManager.getDefaultSharedPreferences(thisRef)
      .getBoolean(property.name, default)

  operator fun setValue(thisRef: ContextWrapper?, property: KProperty<*>, value: Boolean) {
    PreferenceManager.getDefaultSharedPreferences(thisRef)
      .edit()
      .putBoolean(property.name, value)
      .apply()
  }
}

A getter and a setter that uses the usual way to read and write from the preferences. And with this class, we can set up our properties very concisely and elegantly:

var Property1: Boolean by BooleanPrefStore()
var Property2: Boolean by BooleanPrefStore(true)

It even allows us to supply a default value, if it's different from the "default default value". Just create the other helpers classes the same way, IntPrefStore, LongPrefStore or StringPrefStore, if you need them. And then, you simply use these properties or assign values to them, and all will be stored to and retrieved from the preference store automagically.

Just one caveat: the preference storage needs access to the current context. If you declare these properties in an Activity, Fragment or similar Android class that keeps the context, you have nothing else to do. All those classes implement ContextWrapper. But if you need the properties in your own class, you need to make it a ContextWrapper yourself, for instance:

class MyClass private constructor(context: Context) : ContextWrapper(context) {
  ...

Just provide the context when you instantiate it.

score 0 · Answer 4 · answered Mar 12 '22 at 06:17

Easy way of using SharedPreferences in Kotlin

Create an object Preference{}

object Preference {
private const val NAME = "pig"
private const val MODE = Context.MODE_PRIVATE
private lateinit var preferences: SharedPreferences
private val REFER_CODE = Pair("refer_code", "")

fun init(context: Context) {
    preferences = context.getSharedPreferences(NAME, MODE)
}

private inline fun SharedPreferences.edit(operation: (SharedPreferences.Editor) -> Unit) {
    val editor = edit()
    operation(editor)
    editor.apply()
}

var referCode: String
    get() = preferences.getString(REFER_CODE.first, REFER_CODE.second).toString()
    set(value) = preferences.edit {
        it.putString(REFER_CODE.first, value)
    }
   }

Initialize in application class

class App : Application() {


override fun onCreate() {
    super.onCreate()
  
    Preference.init(this)

   }

And use in your Fragment or activity:

 Preference.referCode = "working" // Set value in preference
 Timber.d(Preference.referCode)  // Get value

score -2 · Answer 5 · answered Oct 21 '18 at 23:10

class MyPreference(context:Context) {

val PREFERENCE_NAME="SharedPreferenceExample"
val preference=context.getSharedPreferences(PREFERENCE_NAME,Context.MODE_PRIVATE)

fun getLoginName():String
{
    return "$PREFERENCE_NAME"
}

fun setLoginName(name:String)
{
    val editor=preference.edit()
    editor.putString(PREFERENCE_NAME,name)
    editor.commit()
}

}

Retrieving Value using Shared Preference in Kotlin

5 Answers5