Fix Kotlin App Crash on Orientation Change

When developing Android apps with Kotlin in Android Studio, crashes during screen rotation (orientation change) are common especially for beginners. This article will guide you step-by-step to understand the cause, and fix it properly using best practices. We’ll also include complete code examples split by class for clarity.

Why Kotlin Apps Crash on Orientation Change?

Orientation change forces the Android system to destroy and recreate the activity. If your app doesn’t properly handle state restoration, it may crash—often due to:

• Unhandled null references
• Missing ViewModel usage
• Improper use of Fragment
• Large objects in onSaveInstanceState()
• Incorrect lifecycle handling

How to Fix It (Best Practices)

We’ll build a simple counter app that doesn’t crash on rotation. It uses:

• ViewModel for state retention
• Proper lifecycle observation
• Kotlin best practices

1. MainActivity.kt

package com.example.rotationfix

import android.os.Bundle
import androidx.activity.viewModels
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.Observer
import com.example.rotationfix.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding
    private val counterViewModel: CounterViewModel by viewModels()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.btnIncrement.setOnClickListener {
            counterViewModel.incrementCounter()
        }

        counterViewModel.counter.observe(this, Observer {
            binding.tvCounter.text = it.toString()
        })
    }
}

2. CounterViewModel.kt

package com.example.rotationfix

import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel

class CounterViewModel : ViewModel() {
    private val _counter = MutableLiveData(0)
    val counter: LiveData<Int> = _counter

    fun incrementCounter() {
        _counter.value = (_counter.value ?: 0) + 1
    }
}

3. activity_main.xml (in res/layout)

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

    <TextView
        android:id="@+id/tvCounter"
        android:text="0"
        android:textSize="48sp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/btnIncrement"
        android:text="Increment"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"/>
</LinearLayout>

Tips to Prevent Orientation Crash

• Use ViewModel instead of saving state manually
• Avoid heavy operations in onCreate()
• Separate UI logic and business logic
• Use savedInstanceState only for small data (e.g., scroll position)

Further Reading: Android Lifecycle Management Guide