SharedPreferences in Android — The Complete Guide

This guide covers everything you need to know about SharedPreferences in Android — from understanding when to use it, to saving and retrieving data. All examples are in Kotlin.

What is SharedPreferences?

SharedPreferences is a key-value storage mechanism in Android. Data is stored as XML files in the app’s private directory at /data/data/<package_name>/shared_prefs/.

Use it for small, simple data — user settings, flags, tokens. For structured or relational data, use a database instead.

Creating SharedPreferences

There are two ways:

1. Default SharedPreferences (AndroidX)

val prefs = PreferenceManager.getDefaultSharedPreferences(context)

This creates a file named <package_name>_preferences.xml. Requires the androidx.preference:preference-ktx dependency.

2. Named SharedPreferences

val prefs = context.getSharedPreferences("my_prefs", Context.MODE_PRIVATE)

This creates a file named my_prefs.xml. Use this when you need multiple preference files or want a specific name.

Save Data

Use the edit() method to get a SharedPreferences.Editor, then call the appropriate put method:

val prefs = context.getSharedPreferences("app_prefs", Context.MODE_PRIVATE)

prefs.edit {
  putString("username", "navkrishna")
  putInt("login_count", 5)
  putBoolean("is_logged_in", true)
}

The edit { } extension function (from androidx.core:core-ktx) automatically calls apply() when the block completes.

apply() vs commit()

Method	Behavior
apply()	Writes to disk asynchronously. Preferred in most cases.
commit()	Writes to disk synchronously and returns true/false. Use only when you need to confirm the write succeeded.

Read Data

val prefs = context.getSharedPreferences("app_prefs", Context.MODE_PRIVATE)

val username = prefs.getString("username", "") // default: ""
val loginCount = prefs.getInt("login_count", 0) // default: 0
val isLoggedIn = prefs.getBoolean("is_logged_in", false) // default: false

The second parameter is the default value returned when the key doesn’t exist.

Remove Data

Remove a single key:

prefs.edit {
  remove("username")
}

Clear everything:

prefs.edit {
  clear()
}

Get All Stored Values

To iterate through everything stored in SharedPreferences:

val allEntries = prefs.all

for ((key, value) in allEntries) {
  Log.d("SharedPrefs", "$key = $value")
}

getAll() returns a Map<String, *> — the values can be String, Int, Boolean, Float, Long, or Set<String>.

Complete Example

Here’s a minimal example — an Activity that saves key-value pairs and displays them in a list. Tapping an item removes it.

class MainActivity : AppCompatActivity() {

  private lateinit var prefs: SharedPreferences
  private lateinit var adapter: ArrayAdapter<String>
  private val entries = mutableListOf<String>()

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

    prefs = getSharedPreferences("demo_prefs", MODE_PRIVATE)

    val etKey = findViewById<EditText>(R.id.etKey)
    val etValue = findViewById<EditText>(R.id.etValue)
    val btnSave = findViewById<Button>(R.id.btnSave)
    val listView = findViewById<ListView>(R.id.listView)

    adapter = ArrayAdapter(this, android.R.layout.simple_list_item_1, entries)
    listView.adapter = adapter

    loadEntries()

    btnSave.setOnClickListener {
      val key = etKey.text.toString().trim()
      val value = etValue.text.toString().trim()

      when {
        key.isEmpty() -> etKey.error = "Enter key"
        value.isEmpty() -> etValue.error = "Enter value"
        else -> {
          prefs.edit { putString(key, value) }
          etKey.text.clear()
          etValue.text.clear()
          loadEntries()
        }
      }
    }

    listView.setOnItemClickListener { _, _, position, _ ->
      val key = entries[position].substringBefore(" = ")
      prefs.edit { remove(key) }
      loadEntries()
    }
  }

  private fun loadEntries() {
    entries.clear()
    for ((key, value) in prefs.all) {
      entries.add("$key = $value")
    }
    adapter.notifyDataSetChanged()
  }
}

Layout — activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/etKey"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Key"
        android:inputType="text" />

    <EditText
        android:id="@+id/etValue"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Value"
        android:inputType="text" />

    <Button
        android:id="@+id/btnSave"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Save" />

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

Download Source Code

View on GitHub krrishnaaaa/SharedPreference-Demo