Android the difference between onHandleIntent & onStartCommand

Question

I am currently writing a android program which needs an IntentService. When I put the code in the onHandleIntent function, the code does not run, but it doesn't give errors in the MainActivity. But when I copy my code into the onStartCommand, it runs perfectly.

The problem is that I wanna know what are the differences between onHandleIntent and onStartCommand. Thanks.

CODE:

In onHandleIntent:

System.out.println("SERVICE STARTED! ! !");
//System.out.println(intent.getBooleanExtra("once", Boolean.FALSE));
if (intent.getBooleanExtra("once", Boolean.FALSE)) {
    Check();
}
mHandler.postDelayed(mRunnable, 3000);

Answer 1

As from the docs:

The IntentService does the following:

• Creates a default worker thread that executes all intents delivered to onStartCommand() separate from your application's main thread.
• Creates a work queue that passes one intent at a time to your onHandleIntent() implementation, so you never have to worry about multi-threading.
• Stops the service after all start requests have been handled, so you never have to call stopSelf().
• Provides default implementation of onBind() that returns null.
• Provides a default implementation of onStartCommand() that sends the intent to the work queue and then to your onHandleIntent() implementation.

And also:

All this adds up to the fact that all you need to do is implement onHandleIntent() to do the work provided by the client. (Though, you also need to provide a small constructor for the service.)

So an IntentService is a "Custom" Service with those special properties. So there's no need to override the onStartCommand(), actually, you shouldn't do it unless you're using the regular Service class.

Some example of IntentService usage:

Activity.java

Intent it = new Intent(getApplicationContext(), YourIntentService.class);
it.putExtra("Key", "Value");
startService(it);

YourIntentService.java

public YourIntentService() {
    super("YourIntentService");
}

@Override
protected void onHandleIntent(Intent intent) {

    if (intent != null) {
        String str = intent.getStringExtra("key");
        // Do whatever you need to do here.
    }
    //...
}

You can also check this tutorial or this one for more info about Service and IntentService.

Also, check the docs.