I wrote program for broadcast receiver and service, but i confused in the manifest file there is some ground work to register service and receiver, will any one give me clear idea about this? Thanks in advance.
Service
It is used when you want to do something in background, any long running process can be done using Service in Background.
This will be running always in background even if the application closed
For example, you want to play music when your application gets close. In that case service will be running in background with music.
BroadcastReceiver
It is used when you want to fire some stuff or code during some event. For example, event can be on Boot of Device.
Usually system will send some info which can be recieved by your app if you would wish to ,by registering. And you can do something what you want when that thing happens by using onReceive method. Example is the system will send BroadcastReceiver when new sms arrives or Booting done
for example, If you want to perform something when device Boots, date and time changed etc.
A service is used to perform long running operations without user interaction or to supply functionality to other applications.
A Service needs to be declared in the AndroidManifest.xml via
a <service android:name="yourclasss"> </service> and the implementing class
must extend the Service class or one of its subclasses.
To start Services automatically after the Android system starts you can register
a BroadcastReceiver to the Android android.intent.action.BOOT_COMPLETED system
event. This requires the android.permission.RECEIVE_BOOT_COMPLETED permission.
For more details, check this http://www.vogella.com/articles/AndroidServices/article.html#pre_broadcastreceiver
A broadcast receiver is an Android component which allows to register for system or application events. All registered receivers for an event will be notified by Android once this event happens.
A Service is an application component representing either an application's desire to perform a longer-running operation while not interacting with the user or to supply functionality for other applications to use.
It'll be very long to explain it all here
I've got 2 great tutorial links from vogella
Broadcast Receiver
Service
if you have further question after reading the tutorial feel free to ask me in the comment :)
Related
I'm new to android and trying to build a simple app which needs to listen for incoming sms. I know that I need to use the BroadcastReceiver class and I also know how to make my own broadcast receiver. But how do I start it? Does it start automatically if I set the code for it in the manifest? The app just has the Main activity, do I need to somehow add a broadcast receiver in the onCreate of this activity? I searched for an answer, but it's still not clear to me. I know it's not nice to ask, but it would be great if you can share some sample code. Thanks!
If you declare the receiver within your AndroidManifest.xml, then you shouldn't need to do anything more. When a broadcast gets sent, the Android system will look through all installed apps and notify each app that has declared the appropriate Receiver in its manifest, starting the app in the process if necessary. For most cases, such as SMS, that is how you want to declare receivers, because most broadcasts are sent with the intent that you want to open your app when its not currently running to react to the broadcast.
Alternatively, you may declare the broadcast within a running activity, which may be useful if you want the broadcast to directly update the UI in your running app.
BroadcastReceiver Documentation
I've registered the Intent.action_screen_off/on in my oncreate method of my application, and i can receive the events when my application is running. But when my application exits i get an broadcast intent leaked exception (off the top of my head i think thats what its called, either way its caused by not unregistering my receiver when my app exits)
How can i receive these events when my application is not running? i'd prefer not to use a service or something like that, i've seen other apps do it without services or background processes.
i've seen other apps do it without services or background processes.
That's not possible. The only way to register a BroadcastReceiver other than in running code is to declare it in the AndroidManifest.xml with the relevant <intent-filter>. As it's not possible to do that for either Intent.ACTION_SCREEN_OFF or Intent.ACTION_SCREEN_ON, the apps you've seen MUST have some running component(s) in order to receive the broadcasts.
In short, use a Service - I'm not quite sure why you say you'd prefer not to.
I am going to implement Download Queue for my application. One of its feature will be when Network get connected or disconnected. I want to notify my QueueManger(Service) to update items status and stop.
I know use of Broadcast Receiver and how to use it. My question is if my application is stooped (finished) will broadcast receiver will work? Will it notify application or not?
If not is there any way to achieve this functionality even when application is stooped.
If you register your receiver in the XML instead of programmatically, then it should be able to catch these even when the program is not running.
See question, same solution applies Intent action for network events in android sdk
If you have defined your broadcast receiver as <receiver> in AndroidManifest.xml and listening for android's default action strings, then Yes, it will work.
Otherwise, I would recommend you to make use of Service. It can run silently in the background and do all the logic you want. Your service can even be provoked automatically when the phone is restarted (if you code correctly).
I want to know the difference between services and broadcast receivers, can anyone point out an example that can be observed on android mobile devices.
Thanks
Service: If you want to do something in background , this will be running always in background even if the application closed. You can create this in separate process and also you can give your service to other app if you want. Downloading any content or Music is good example
Broadcast Reciever: Usually system will send some info which can be recieved by your app if you would wish to ,by registering. And you can do something what you want when that thing happens by using onReceive method.
Example is the system will send BroadcastReceiver when new sms arrives or Booting done
Here is good article : Service and BroadcastReceiver
Service is used when you want to do something in background, any long running process can be done using Service in Background. For example, you want to play music when your application gets close. In that case service will be running in background with music.
Example of Service
BroadcastReceiver is used when you want to fire some stuff or code during some event. For example, event can be on Boot of Device. If you want to perform something when device Boots, date and time changed etc...
Example of BroadcastReceiver
I think of it possibly a different way. A Service receives intents that were sent specifically to your application, just like an Activity. A Broadcast Receiver receives intents that were broadcast system-wide to all apps installed on the device.
(The reason I say a Service is a bit like an Activity is that: You wouldn't broadcast a message saying "start Activity MyActivity" across all apps installed on the device. It is only for your specific app.)
Of course, as others mentioned, a Service can continue running in the background, whereas a Broadcast Receiver should finish quickly (e.g. if it is running for more than 5 seconds it may be killed by the OS). The Broadcast Receiver can still run in the background (when app is closed) under certain circumstances. For this, it's worth mentioning that there are actually two types of Broadcast Receivers - Manifest-declared, and Context-registered. They have different lifespans and restrictions - the former can receive broadcasts in the background with certain restrictions, while the latter cannot receive broadcasts in the background (app must be running and active) but has no restrictions on the types of intents that can be received.
Both services and broadcast receivers must be specifically invoked (via an intent), but for services this is usually a specific call (e.g. when your app is started or when the user clicks some button) whereas for broadcast receivers they don't need to be explicitly started as they will start anyway when a relevant broadcast is made.
Here's how I would think of it:
Type
Displays UI?
Can continue running for a long time when app is closed?
Can receive intents when app is closed?
Intents must specifically target your app?
Restricted list of intents that can be specified?
Activity
Yes
No
Yes
Yes
No
Service
No
Yes
Yes
Yes
No
Manifest-declared Broadcast Receiver
No
No
Yes
No
Yes1
Context-registered Broadcast Receiver
No
No
No
No
No
1: Only if you target Android 8.0 or above. The restrictions are not applied if the intent specifically targets your app. The restricted list of intents can be found here.
What is a BroadcastReceiver? What are its uses and how can I use it?
Start by reading the documentation. Also, copying from Application Fundamentals:
Broadcast receivers
A broadcast receiver is a component that responds to system-wide
broadcast announcements. Many
broadcasts originate from the
system—for example, a broadcast
announcing that the screen has turned
off, the battery is low, or a picture
was captured. Applications can also
initiate broadcasts—for example, to
let other applications know that some
data has been downloaded to the device
and is available for them to use.
Although broadcast receivers don't
display a user interface, they may
create a status bar notification to
alert the user when a broadcast event
occurs. More commonly, though, a
broadcast receiver is just a "gateway"
to other components and is intended to
do a very minimal amount of work. For
instance, it might initiate a service
to perform some work based on the
event.
A broadcast receiver is implemented as a subclass of
BroadcastReceiver and each broadcast
is delivered as an Intent object. For
more information, see the
BroadcastReceiver class.
Finally, read in Common Tasks how you can utilize BroadcastReceivers to listen for messages and set alarms.
A broadcast is generated by android on occurrence of some action , BroadcastReceiver class enables the developer to handle the situation on occurence of the event/action . Action can be arrival of msg or call , download complete , boot completed , etc.
Broadcast Receivers simply respond to broadcast messages from other applications or from the system itself. These messages are sometime called events or intents. For example, applications can also initiate broadcasts to let other applications know that some data has been downloaded to the device and is available for them to use, so this is broadcast receiver who will intercept this communication and will initiate appropriate action.
I like this slide, because it focuses on Broadcast Receiver and offers simple description. The minor problem is that the updated date was a little bit old ( in 2011 ).
Link
Android Application Component: BroadcastReceiver Tutorial
(retrieved from the slide)
Broadcast Receiver
Receives and Reacts to broadcast Intents
No UI but can start an Activity
Extends the BroadcastReceiver Base Class
BroadCastReciever is an Android Component that helps you to know handle registered System Events or Application Events.
For Example:
System Events Such us : the screen has turned off, the battery is low, or a picture was captured.
Applications can also initiate broadcasts—for example, to let other applications know that some data has been downloaded to the device and is available for them to use... etc
In simple terms
A broadcast receiver is basically an interface that you can implement so that your app can subscribe to system changes like when the system has finished booting, or a charger is connected/disconnected or airplane mode is switched on/off etc.