Need your help or advice.
The aim is to get continuous updates from method android.telephony.CellSignalStrengthWcdma.getDbm() (Get the mobile network signal strength as dBm) and make update of correspondent text view when the value provided by the method changes.
The first approach of the solution is to request for value in do-while cycle with predefined time interval, like 1 second, check the difference between common and previous values and make decision of textView update.
So the question is maybe there is some other better way to do this, like using kind of system listener etc?
BR,
You need to add a PhoneStateListener to your TelephonyManager using the proper method listen(). You need to pass a sub class of PhoneStateListener and the event you want to get. For example you can listen for PhoneStateListener.LISTEN_CELL_INFO; in this case the method onCellInfoChanged (List cellInfo) of your PhoneStateListener is called, providing you the info you need, avoiding a loop.
Related
In Choreographer.FrameCallback.doFrame event, their a value called frameTimeNanos. what exactly mean this value and more important how to use it, I mean in with scenario we need to take care of this value?
I am trying to implement a series of notifications based on radio button options the user selects. The notifications date and time will set depending on both radio button options and the user selected date.
for example the user selects Option 1, 2 and 3 along with Jan 1st 2017 and 12 notifications are set every couple of days/weeks depending on said options.
Before I get too far into this, am I just looking at a complex if then statement to set these notifications or am i missing another solution?
When your if-else statements get too long you might be needing a switch statement instead. You said there are twelve notification options so a switch could do this just fine.
https://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html
Remember to separate each option in a modular fashion using different classes, or methods so that you just have to call each block of code.
A lot of switcing or if/else can also be a symptom of you trying to express intrinsically polymorphic code. You are essentially replicating the vtable the compiler would do for you. Following separating business logic from view (rendering) logic -- ie some form of MVC -- you could associate a subclass with each radio button to which the button delegates the logic when it is pressed (btw you might not necessarily need separate subclasses). The controller of each radio button may have a reference to some other object which stores the final frequency of days/hours/minutes, etc for each to call the alarm. So as each radio button is pressed, it delegates to its controller which in turn interprets the value of the radio button and in turn calls into the alarm controller, incrementing / decrementing some value using some appropriate API.
I know it might sound like over-engineering but it is quite simple to set up and it is likely that you will minimally need that alarm controller for other details (which also makes it a lot easier to test; you definitely do not want to shove business logic in your views (activities) as it makes testing a nightmare). So if you wish to simplify this, you could forego each button's individual controller and instead have each button directly invoke the alarm controller API if you prefer to update it.
I have elements in a listview that change the way they look based on a network response
by the time the network responds the listview item (or item in the arraylist) could be at a different index
What I can do:
Make an alternate api call back to the server which returns all the items in the list (in their most updated form), and then call notifyDataSetChanged() on the adapter
but this seems like a waste of processes, and so does some alternative of searching an arraylist for the equivalent object, updating it and then calling notifyDataSetChanged()
Is there a way instead to have something like a BroadcastReceiver within the adapter that can keep track of the adapter item which started the network call or service? any maybe only respond to the receiver if the view is not currently recycled
It's hard to give an exact answer as your best approach since what you described is a really high level overview. I'll have to give an equal high level answer. Hopefully it help.
There's not many ways around searching an ArrayList in the adapter for a given item. One good idea:
You could create a custom adapter which is backed by an ArrayList but also maintains a Set of the data as well. The benefit is finding an item is O(1) however any adds or removes require you to modify two collections instead of one...which will cause a slight slow down. I've personally had to use this solution once for a highly complex adapter/listview. It could get updated quite often (to the point throttling notifyDataSetChanged() was once discussed) Surprisingly the slow down in maintaining a List and Set was hardly noticeable and overall worked well.
You could use a similar approach if your data has some sort of unique id associated with it. In which case you could build a Map of the data and use the maps values() method to obtain the List to use for the adapter. While using the keys to quickly find and update the required data. This may or may not be more difficult then the Set idea. Further if you can get your data into a SparseArray (having a unique int for each item), then you could use a SparseArrayAdapter which can get you O(log n) search times. Of course you loose the ability to sort your data in any meaningful way.
I'm not sure how viable the BroadcastReceiver idea is. I would see it more like each item's object instance would control the network request/response for itself, but that would seem tricky and odd. There's always the option of using a CursorAdapter. Just store all your data to DB. Have the network calls update the DB which can then be reflected within the CursorAdapter.
I want registered callback method using sqlite trigger
for example,
public void printLog(){
Log.i("TAG","1 row added");
}
this method calling after insert any row in sqlite.
Is it possible?
How to do that?
SQLite provides Data Change Notification Callbacks. I don't think that Android exposes them directly but it does have for example CursorAdapter which provides some change notifications.
You can use also use the getContentResolver().registerContentObserver but unfortunately it doesn't tell you what kind of change was made, it could be a delete, insert or update.
If you control the ContentProvider that interfaces with the DB then you could fire an Intent or use getContentResolver().notifyChange to send a special Uri notification that identifies both the table and action. An example Uri you could notify with might be: content://my-authority/change/table-name/insert
But even then you don't know exactly which rows were effected by the change.
Seems like triggers that write to a change log table will guarantee you hear about all changes regardless of where they came from, and you can know the exact id and action that occurred. Unfortunately it means slower inserts/updates/deletes and it means you probably need a Service of some kind to process and delete changes.
I'd love to hear if these is some better solution out there!
You can set content observer this link will help Receives call backs for changes to content http://developer.android.com/reference/android/database/ContentObserver.html
I need some help getting info from the orientation sensor. As I have seen in just about every tutorial/guide out there, the values are passed to an event (onSensorChanged(SensorEvent event) in which they can be manipulated.
My problem is that I don't want to keep the electro-magnetic/orientation sensor running constantly (for the sake of battery life). I want to be able to turn it on, grab the current value and switch it off. Is there any way to do this?
I have done some searching and found that I can try multi-threading, but I'm not fully comfortable with that.
What I'm looking for is something like (Sorry for lack of formatting I can't seem to figure it out):
private void getOrientationNOW() {
m_SensorManager.registerListener(mySensorEventListener, m_MagneticSensor, SensorManager.SENSOR_DELAY_FASTEST);
//---->Something here to get the current value from the sensor
m_SensorManager.unregisterListener(mySensorEventListener);
}
If this is possible, please help me!
Thank you all in advance!
When you register a listener for a sensor the activity will be called every time the sensor values changes according to the parameters. So if you want to get the values only one once what you could do is unregister the listener for that sensor after getting the value once.