I'm confusing about these question.please help me in these question
Many applications registered the broadcast receiver with the same action and one application send the broadcast then what will happen?
Does all apps will receive the that intent or only one app will receive the intent ?
can we registered the multiple receivers in the same application?
if we registered the two receivers with same action in the same application then what will happen?
All receivers will receive the broadcast.
Broadcast Receivers are designed to provide notification about a single event to multiple receivers.
There is only one exception to this statement, if a broadcast is an Ordered broadcast, then the broadcast will be propagated sequentially to all receivers one after another(based on priority) and any of the receiver can decide to prevent broadcast from propagating further. The broadcast receiver for SMS is a good example of ordered broadcast.
Yes, multiple receivers can be registered in the same app.
Both the receivers will receive the intent as expected.
Related
I want to know all broadcast message that occur at Android system or third-party application.
Broadcast messages that occur at Android system are so easy to know because make broadcast receiver, add intent-filter(all broadcast action) and receive :).
But messages that occur at third-party application are difficult to know because i don't know there broadcast message action :(
How to receive broadcast intent at third-party application?
There is no way to indiscriminately register for any broadcast event, but you can list all historical broadcasts and registered broadcast receivers with the following terminal command:
dumpsys activity broadcasts
Essentially, you would receive only those broadcasts for which you have registered. It is not feasible/possible to receive all the broadcasts. In fact, if it is somehow possible, it would be a HUGE security breach !!!
As we all know, in android when u registered a broadcast, it will send a broadcast to the the BroadcastReceiver, the send count is belong to the intent action count, how i distinguish the registered broadcast and system broadcast?
when u regiter WifiManager.WIFI_STATE_CHANGED_ACTION the broadcast will receive the notification immediately i called it registered broadcast
If the criteria you are concerned about is the "receive the notification immediately" part, that is because it is a sticky broadcast, and so you will receive the last-broadcast Intent for that action immediately, in addition to future broadcasts while you are registered.
how i distinguish the registered broadcast and system broadcast?
If you mean "how do I distinguish when I get the first 'sticky' broadcast versus later ones", ideally your code does not care about this. I would consider that to be a code smell.
If you are absolutely certain that you need to handle the first broadcast differently, use a boolean to track whether or not a broadcast is the first one.
Is it correct, that, if the broadcast is sent while there is no registered broadcast receiver, the broadcast is lost?
For some reason i thought, that if the broadcast was sent while there was no active receiver, the broadcast would "circle around" the app (I am using LocalBroadcastManager) and would be delivered to a receiver, if such receiver was registered later.
P.s. I've seen in many examples, where the receiver is released when the activity goes in background. I guess that is for improving resource management. So my other question is, if i wanted my activity to receive broadcasts while being in background, would it be a major resource waste if i kept the receiver active during all of the activity life duration?
What happens to an intent if it is broadcast with no registered receivers currently present? Is it waiting in a queue until someone can receive it or is it just gone?
It depends on how you send the broadcast. For example if the code says:
Intent intent = new Intent(AN_ACTION);
sendStickyBroadcast(intent);
The broadcast will be held by the system.
Whenever anyone registers to receive a sticky broadcast they receive the most recent one sent.
If the broadcast is not sticky, then, yes, it disappears if there are no registered receivers.
A fellow developer and I have started to question whether a broadcast announcement is guaranteed to be received by the appropriate broadcast receiver.
We have a broadcast receiver which receives messages that should be put on to the screen. Occasionally we notice that some messages never make it to the screen.
Even with the debugger, it has been hard to tell for certain if the receiver is not getting the broadcast or if it due to our own bugs that the broadcast is never sent.
So I wanted to ask generally if there are any known reasons why the broadcast receiver would not receive an announcement?
There are ordered broadcasts in Android. They are sent to receivers according to the receivers priority. And receiver with a higher priority can abort the broadcast spreading.
See this blog post for details.