Kotlin App Freezing? Causes & Fixes in Android Studio

Is your Kotlin Android app freezing or becoming unresponsive? This is a common issue faced by many developers, especially when working with background tasks, large data operations, or UI-thread mismanagement. In this article, we’ll explore the most frequent causes of app freezing in Kotlin, how to identify them using Android Studio, and provide complete sample code for practical fixes.

Common Causes of Freezing in Kotlin Apps:

1. Blocking the Main Thread
   Heavy operations (like JSON parsing or DB queries) must not run on the UI thread.
2. Improper Use of Coroutines
   Using runBlocking or forgetting withContext(Dispatchers.IO) can freeze your app.
3. Memory Leaks
   Unreleased resources or misused context can cause the app to hang or freeze.
4. Large RecyclerView Data Without Paging
   Loading thousands of items without pagination or virtualization leads to slow UI.
5. Nested Loops or Long Computations on UI Thread
   Avoid CPU-intensive operations on the main thread.

Solution Using Kotlin Coroutines (With Code)

1. MainActivity.kt

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import kotlinx.coroutines.*

class MainActivity : AppCompatActivity() {

    private val coroutineScope = CoroutineScope(Dispatchers.Main + Job())

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

        coroutineScope.launch {
            val data = withContext(Dispatchers.IO) {
                // Simulate heavy operation
                fetchDataFromApi()
            }
            updateUI(data)
        }
    }

    private fun fetchDataFromApi(): String {
        Thread.sleep(2000) // simulate long-running task
        return "Data fetched"
    }

    private fun updateUI(data: String) {
        println(data) // In real app, update UI elements
    }

    override fun onDestroy() {
        super.onDestroy()
        coroutineScope.cancel()
    }
}

build.gradle (Module)

dependencies {
    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3'
}

Additional Fixes:

• Use ViewModel + LiveData to observe data without blocking UI.
• Monitor ANR logs from Android Studio’s Logcat.
• Optimize RecyclerView with DiffUtil and Paging library.

External Resource:

Learn more about Avoiding ANRs in Android.