Top 10 Android Memory Leak Causes

3 min readNov 19, 2023

Addressing memory leaks in Android development is crucial for creating efficient and reliable applications. Memory leaks occur when objects are no longer needed but still occupy memory because they are not properly released. Here are five common memory leaks in Android, along with Kotlin code examples and solutions:

1. Non-Static Inner Classes

Problem: Inner classes in Kotlin can hold an implicit reference to their outer class.

class MyActivity : AppCompatActivity() {
     private inner class MyThread : Thread() {
         override fun run() {
             // Task
         }
     } 
}

Solution: Make the inner class static or use a separate class. If needed, pass a weak reference to the outer class.

2. Handlers and Runnables

Problem: Handlers can cause memory leaks if they hold a reference to an outer class.

class MyActivity : AppCompatActivity() {
     private val handler = Handler(Looper.getMainLooper())
     private val runnable = Runnable { /* Task */ }
     override fun onDestroy() {
         super.onDestroy()
         handler.removeCallbacks(runnable)
     } 
}

Solution: Remove any callbacks in the onDestroy method.

3. Anonymous Listeners

Problem: Anonymous listeners can inadvertently hold a reference to the activity or view.

class MyActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         findViewById<Button>(R.id.myButton).setOnClickListener {
             // Click action
         }
     } 
}

Solution: Clear the listener in the onDestroy method or use a static class.

4. Static Views or Contexts

Problem: Static views or context references can lead to memory leaks.

class MyActivity : AppCompatActivity() {
     companion object {
         private var staticView: View? = null
     }
     override fun onCreate(savedInstanceState: Bundle?) {
         staticView = findViewById(R.id.myView)
     } 
}

Solution: Avoid static references to views or contexts; use weak references if necessary.

5. Improper LiveData Observations

Problem: Observing LiveData without considering the lifecycle.

class MyActivity : AppCompatActivity() {
     private val viewModel: MyViewModel by viewModels()
      override fun onCreate(savedInstanceState: Bundle?) {
         viewModel.myLiveData.observe(this, { data ->
             /* Update UI */ 
          })
     }
}

Solution: Observe LiveData using lifecycle-aware components, like viewLifecycleOwner in Fragments.

6. Singleton with Context

Problem: Singletons holding a reference to a context can cause leaks.

object MySingleton {
     var context: Context? = null 
}

Solution: Pass the application context to singletons instead of an activity or view context.

7. Bitmaps

Problem: Large bitmaps can consume a lot of memory if not managed properly.

class MyActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         val bitmap = BitmapFactory.decodeResource(resources, R.drawable.large_image)
         // Use bitmap
     } 
}

Solution: Use Bitmaps judiciously and call recycle() when done; consider using image loading libraries like Glide or Picasso.

8. WebViews

Problem: WebViews can hold a reference to the context.

class MyActivity : AppCompatActivity() {
     private lateinit var webView: WebView 
     override fun onCreate(savedInstanceState: Bundle?) {
         webView = findViewById(R.id.myWebView)
         // Set up WebView
     } 
}

Solution: Clear the WebView in the onDestroy method and use application context where possible.

9. Broadcast Receivers

Problem: Not unregistering broadcast receivers can lead to leaks.

class MyActivity : AppCompatActivity() {
     private val receiver = MyReceiver()
      override fun onStart() {
         registerReceiver(receiver, IntentFilter("SOME_ACTION"))
     }
     override fun onStop() {
         unregisterReceiver(receiver)
         super.onStop()
     } 
}

Solution: Always unregister receivers in the corresponding lifecycle method.

10. Event Listeners in RecyclerView Adapters

Problem: Event listeners in RecyclerView adapters can hold a reference to the Activity or Fragment.

class MyAdapter(private val items: List<Item>, private val activity: AppCompatActivity) : RecyclerView.Adapter<MyViewHolder>() {
     // Adapter implementation 
}

Solution: Use interfaces or lambda functions for callbacks and avoid passing the activity or fragment context to adapters.

General Advice

Regularly check for memory leaks in your Android applications, especially after making changes to the code involving contexts, views, or background tasks.
Use tools like LeakCanary for detecting memory leaks during the development phase.
Understanding and managing the lifecycle of Android components is key to preventing memory leaks.

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