SharedPreferences / DataStore in Android Kotlin - Mini App: Build & Ship

Build: Settings Screen

This screen lets the user save and load a username using SharedPreferences. The user can enter a name, save it, and see the saved name displayed.

Target UI

-------------------------
|       Settings        |
|-----------------------|
| Enter username:       |
| [______________]      |
|                       |
| [ Save ]              |
|                       |
| Saved username:       |
| [No username saved]   |
-------------------------

Add an EditText for username input

Add a Save button that saves the username to SharedPreferences

Display the saved username below the button

Load and show the saved username when the screen opens

Starter Code

Android Kotlin

package com.example.settingsapp

import android.content.Context
import android.content.SharedPreferences
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class SettingsActivity : AppCompatActivity() {
    private lateinit var usernameEditText: EditText
    private lateinit var saveButton: Button
    private lateinit var savedUsernameTextView: TextView
    private lateinit var sharedPreferences: SharedPreferences

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

        usernameEditText = findViewById(R.id.usernameEditText)
        saveButton = findViewById(R.id.saveButton)
        savedUsernameTextView = findViewById(R.id.savedUsernameTextView)

        sharedPreferences = getSharedPreferences("MyPrefs", Context.MODE_PRIVATE)

        // TODO: Load saved username and display it

        // TODO: Set saveButton click listener to save username
    }
}

Task 1

Task 2

Task 3

Solution

Android Kotlin

package com.example.settingsapp

import android.content.Context
import android.content.SharedPreferences
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity

class SettingsActivity : AppCompatActivity() {
    private lateinit var usernameEditText: EditText
    private lateinit var saveButton: Button
    private lateinit var savedUsernameTextView: TextView
    private lateinit var sharedPreferences: SharedPreferences

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

        usernameEditText = findViewById(R.id.usernameEditText)
        saveButton = findViewById(R.id.saveButton)
        savedUsernameTextView = findViewById(R.id.savedUsernameTextView)

        sharedPreferences = getSharedPreferences("MyPrefs", Context.MODE_PRIVATE)

        // Load saved username and display it
        val savedUsername = sharedPreferences.getString("username", null)
        if (savedUsername != null) {
            savedUsernameTextView.text = savedUsername
        } else {
            savedUsernameTextView.text = "No username saved"
        }

        // Save username on button click
        saveButton.setOnClickListener {
            val username = usernameEditText.text.toString()
            if (username.isNotBlank()) {
                sharedPreferences.edit().putString("username", username).apply()
                savedUsernameTextView.text = username
            }
        }
    }
}

This code uses SharedPreferences to save and load a username.

When the screen opens, it reads the saved username from SharedPreferences. If there is one, it shows it; otherwise, it shows a default message.

When the user types a username and taps Save, the app saves the username in SharedPreferences and updates the displayed saved username immediately.

This way, the username stays saved even if the app is closed and reopened.

Final Result

Completed Screen

-------------------------
|       Settings        |
|-----------------------|
| Enter username:       |
| [Alice__________]     |
|                       |
| [ Save ]              |
|                       |
| Saved username:       |
| Alice                 |
-------------------------

User types a name in the input box

User taps Save button

The typed name is saved and shown below

When reopening the screen, the saved name is shown automatically

Stretch Goal

Add a Clear button that removes the saved username from SharedPreferences and updates the display

💡 Hint

Use sharedPreferences.edit().remove("username").apply() and update the TextView to show 'No username saved'