Best way to perform an action periodically [while an app is running] - Handler?

I'm doing something similar in my android app; I update some data in my interface every 10 seconds. There are many ways to do this, but I chose to use a Handler because it's very simple to implement:

Thread timer = new Thread() {    public void run () {        for (;;) {            // do stuff in a separate thread            uiCallback.sendEmptyMessage(0);            Thread.sleep(3000);    // sleep for 3 seconds        }    }});timer.start();...private Handler uiCallback = new Handler () {    public void handleMessage (Message msg) {        // do stuff with UI    }};

As you may know, you cannot run periodic functions like this in the UI thread, because it will block the UI. This creates a new Thread that sends a message to the UI when it is done, so you can update your UI with the new results of whatever your periodic function does.

If you do not need to update the UI with the results of this periodic function, you can simply ignore the second half of my code example, and just spawn a new Thread as shown. Beware, however: if you are modifying variables shared by this new Thread and the UI, you are going to run into problems if you don't synchronize. In general, threading is not an area where you want to ignore "good programming practices" because you'll get strange, non-predictable errors and you'll be cursing your program.

-tjw

The simplest thing is to use postDelayed() on a View (e.g., a widget) to schedule a Runnable that does work, then reschedules itself.

// We need to use this Handler packageimport android.os.Handler;// Create the Handler object (on the main thread by default)Handler handler = new Handler();// Define the code block to be executedprivate Runnable runnableCode = new Runnable() {    @Override    public void run() {      // Do something here on the main thread      Log.d("Handlers", "Called on main thread");      // Repeat this the same runnable code block again another 2 secs      // 'this' is referencing the Runnable object      handler.postDelayed(this, 2000);    }};// Start the initial runnable task by posting through the handlerhandler.post(runnableCode);