Kotlin Lateinit Property Not Initialized: Fix It Now

If you’re developing an Android app using Kotlin and encounter the dreaded kotlin.UninitializedPropertyAccessException: lateinit property ... has not been initialized, this guide will help you solve it with clear code examples and proper explanation. This error usually occurs when you declare a property using lateinit but forget to initialize it before accessing it. Here’s how to avoid and fix it in Android Studio.

1. What is lateinit in Kotlin?

The lateinit modifier in Kotlin is used to tell the compiler that a variable will be initialized later. It’s commonly used for non-null properties that are initialized after the object is created, such as in Activity or Fragment classes in Android.

private lateinit var myTextView: TextView

This allows you to avoid initializing it during declaration, but be careful — using it without proper initialization will crash the app.

2. The Error Explained

Error Message:

kotlin.UninitializedPropertyAccessException: lateinit property myTextView has not been initialized

Cause:
You are trying to access a lateinit variable before it has been assigned a value.

3. How to Fix It

Solution 1: Initialize Before Use

Make sure you are initializing the lateinit property in the appropriate lifecycle method.

MainActivity.kt:

class MainActivity : AppCompatActivity() {

    private lateinit var myTextView: TextView

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

        // ✅ Correct initialization
        myTextView = findViewById(R.id.textView)
        myTextView.text = "Hello, Kotlin!"
    }
}

Solution 2: Use :: to Check Initialization

Kotlin provides a way to check whether a lateinit variable has been initialized:

if (::myTextView.isInitialized) {
    myTextView.text = "Initialized"
} else {
    Log.d("MainActivity", "TextView is not initialized yet.")
}

Solution 3: Avoid lateinit When Not Needed

If possible, consider using nullable types (TextView?) or lazy initialization if the variable doesn’t need to be reassigned:

private val myTextView by lazy {
    findViewById<TextView>(R.id.textView)
}

4. Best Practices

• Only use lateinit when you’re 100% sure it will be initialized before any access.
• Prefer lazy for single-assignment properties.
• Use ::variable.isInitialized to check before accessing.

5. Bonus: Full Example with Proper Use

MainActivity.kt:

class MainActivity : AppCompatActivity() {

    private lateinit var myButton: Button
    private lateinit var myTextView: TextView

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

        myButton = findViewById(R.id.button)
        myTextView = findViewById(R.id.textView)

        myButton.setOnClickListener {
            if (::myTextView.isInitialized) {
                myTextView.text = "Button clicked!"
            }
        }
    }
}

6. Additional Resource

You can also learn more from the Kotlin official documentation on lateinit.