Android Tutorial

Software Setup and Configuration

Android Studio

File Structure

Components

Core Topics

Layout

View

Button

Intent and Intent Filters

Toast

RecyclerView

Fragments

Adapters

Other UI Component

Image Loading Libraries

Date and Time

Material Design

Bars

Working with Google Maps

Chart

Animation

Database

Advance Android

Jetpack

Architecture

App Publish

App Monetization

MultiThreading in Android with Examples

Multithreading is a powerful tool in Android to avoid performing resource-intensive tasks on the main (or UI) thread, which can freeze the UI and make applications unresponsive. There are various mechanisms in Android to handle multithreading:

1. Threads:

The most basic way is to use the Thread class.

Example:

val thread = Thread {
    // Perform some background work here.
}
thread.start()

However, when using threads directly, you need to handle thread synchronization and communication back to the main thread manually.

2. AsyncTask:

AsyncTask allows you to perform background operations and then publish the results on the UI thread. However, starting from Android R, AsyncTask is deprecated.

Example:

private class MyTask : AsyncTask<Void, Void, String>() {

    override fun doInBackground(vararg params: Void?): String {
        // Perform background work.
        return "Result"
    }

    override fun onPostExecute(result: String) {
        // This runs on the UI thread, use result here.
    }
}

To execute: MyTask().execute()

3. Handler and Looper:

Handlers are used to send and process Message and Runnable objects associated with a thread's MessageQueue.

Example:

val handler = Handler(Looper.getMainLooper())

val runnable = Runnable {
    // Execute tasks
}

// Post the Runnable to be executed
handler.post(runnable)

4. HandlerThread:

This is a handy class for starting a new thread that has a looper.

Example:

val handlerThread = HandlerThread("BackgroundHandlerThread")
handlerThread.start()

val handler = Handler(handlerThread.looper)

handler.post {
    // Background task
}

5. Executors and ThreadPoolExecutor:

This provides a higher-level replacement for AsyncTask, allowing you to manage a pool of worker threads.

Example:

val executor: Executor = Executors.newSingleThreadExecutor()

executor.execute {
    // Perform background work here.
}

6. Coroutine:

With Kotlin, coroutines provide a more efficient and simpler way to handle asynchronous tasks and multithreading.

Example:

GlobalScope.launch(Dispatchers.IO) {
    // Perform background work here.

    withContext(Dispatchers.Main) {
        // Update UI on main thread
    }
}

7. RxJava:

It's a library for composing asynchronous and event-based programs using observable sequences.

Example:

Observable.fromCallable {
    // Background work
}
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe { result ->
    // Update UI with result
}

Note: Always remember to manage the lifecycle of threads, especially when they are linked with lifecycle-aware components like Activities or Fragments, to prevent memory leaks and unexpected behavior. Using higher-level tools like Coroutines or RxJava makes lifecycle management easier and more intuitive.

Android AsyncTask example code:

AsyncTask allows you to perform background operations and publish results on the UI thread.

public class MyAsyncTask extends AsyncTask<Void, Void, String> {

    @Override
    protected String doInBackground(Void... params) {
        // Background task
        return "Task completed";
    }

    @Override
    protected void onPostExecute(String result) {
        // UI thread, update UI with the result
        textView.setText(result);
    }
}

// Execute the AsyncTask
new MyAsyncTask().execute();

Using threads and handlers in Android app development:

Create a worker thread and use a handler to communicate with the UI thread.

new Thread(() -> {
    // Background task
    String result = performBackgroundTask();

    // Update UI using handler
    handler.post(() -> textView.setText(result));
}).start();

Concurrency in Android with Java threads:
- Use Java threads for concurrent processing.
```
new Thread(() -> {
    // Background task
}).start();
```

Working with ThreadPoolExecutor in Android:

Use ThreadPoolExecutor for managing a pool of worker threads.

ThreadPoolExecutor executor = new ThreadPoolExecutor(
    2, // Core pool size
    5, // Maximum pool size
    60, // Keep-alive time in seconds
    TimeUnit.SECONDS,
    new LinkedBlockingQueue<>()
);

executor.execute(() -> {
    // Background task
});

Thread synchronization examples in Android:

Use synchronization to control access to shared resources.

private static final Object lock = new Object();

synchronized void synchronizedMethod() {
    // Code requiring synchronization
}

Handling background tasks with AsyncTaskLoader in Android:

AsyncTaskLoader provides a loader that performs asynchronous loading of data.

public class MyLoader extends AsyncTaskLoader<String> {

    @Override
    public String loadInBackground() {
        // Background task
        return "Loader completed";
    }
}

// Initialize and start the loader
LoaderManager loaderManager = getSupportLoaderManager();
Loader<String> loader = loaderManager.initLoader(1, null, new MyLoaderCallbacks());
loader.forceLoad();

These examples cover AsyncTask, threads and handlers, concurrency with Java threads, ThreadPoolExecutor, thread synchronization, AsyncTaskLoader, and multithreading patterns and anti-patterns in Android. Choose the appropriate approach based on the requirements of your background tasks.