What is Handler in Android SDK?

In Android SDK, a Handler is designed to manage and schedule messages and runnable tasks to be executed on a thread's message queue, especially within the context of the main UI thread. It helps facilitate communication between a background thread and the UI thread, allowing developers to safely update UI components from background operations. Handlers are commonly used for tasks such as posting delayed messages, immediate execution of a task, or sending and receiving Message objects between threads.

Incorporating a Handler can be crucial for ensuring smooth UI experience since it can prevent performance lag caused by operations running on the main thread.

Below is an example of using a Handler in Android:

// Creating a new Handler Handler handler = new Handler(Looper.getMainLooper()); // Posting a task to be executed on the main thread handler.post(new Runnable() { @Override public void run() { // This code will run on the UI thread Toast.makeText(context, "Task executed on UI thread!", Toast.LENGTH_SHORT).show(); } }); // Posting a delayed task handler.postDelayed(new Runnable() { @Override public void run() { // This code will execute after a delay of 3 seconds Toast.makeText(context, "Delayed task executed!", Toast.LENGTH_SHORT).show(); } }, 3000);

Android Handler UI thread background tasks main thread Android SDK

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