Would it be there noticeable speed improvement if I would create local references to needed view elements (e.g. EditText or Button) in my activity (in onCreate()) and use them for accessing needed elements or it does not much matter if I always use findViewById() when I need to access some particular element?
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first of all: yes, I read all the other threads on this topic. And not only those from this site... (you see, i'm a little frustrated) Most of them come with the advice to use "android:id" instead of just "id" in the xml file. I did. From others, i learned, that View.findViewById works different than Activity.findViewById. I handled that, too.
in my location_layout.xml i use
<FrameLayout .... >
<some.package.MyCustomView ... />
<LinearLayout ... >
<TextView ...
android:id="@+id/txtLat" />.................
I am creating an EditText object which i then try to reference in a unit test. what is the best way to add a new 'id' to R.id for this dynamically created object so that i can later reference it via findViewById() in the unit test?
View 2 Replies View RelatedI wrote CustomView Class, and load it in layout. so i trid to find CustomView using findViewById() in activiy to get handle. but findViewById() was return null.
Written Code is like below:
CODE:.........
MapCanvas.java:
CODE:...............
I have a custom view that needs a reference to the activity that created it.Dianne Hackborn said in another thread: >Give your view a reference to the activity (or a Java interface it implements) and call back through that. >Much much MUCH more efficient than sending a broadcast. >See all of the standard view and view subclass callbacks for examples.
View 9 Replies View RelatedSo say there's an app running (any app). I'd like to be able to get it's Activity from within a Service that will be triggered to run from a android.intent.action.SEARCH_LONG_PRESS.
Is this possible?
I want to have a class "Utils", that will have several methods used all over my code. For example, I have a top bar with a textview and two ImageButtons that must display different texts and icons on different activities.I created the class Util, but it doesn't extend Activity. The problem is that if it doesn't, findViewById isn't there, can't find stuff etc.
View 1 Replies View RelatedI want to pass a class reference to an activity, and then the activity will construct the view according to the content of the class.
How could I implement this function?
I have an AsyncTask that scans the file system and publishes progress through Notifications. To do this I need a reference to the current Activity in the AsyncTask.
I also don't want to kill the task when the activity is destroyed. How do I avoid leaking the activity and everything it references on each configuration change?
One possibility is to remove the reference in OnPause() to be sure it is gone when the Activity is destroyed, but that would mean notifications stops coming as soon as you leave the activity which is no good.
Isn't there a recommended way of dealing with AsyncTasks in this way?
Starting from the example ServiceStartArguments.java of the "API demos", the service "ServiceStartArguments" is creating a new Handler object (ServiceHandler) which does all the work in a separate thread. Once that work is completed, how can I tell other components that my work is finished, and also provide data (that resulted from the work) to them?
I tried something like startActivity(intent_transferred_via_msg) which does not work, I'll get an exception because I call it "outside of the service", which is technically true.
I'm trying to create a program with a service that runs every 10 seconds, puts the camera preview, taking a picture and then leaving the user to continue his work (closing down). Currently I have two problems:
1. After I'm taking the picture, the preview still there. There's no function like close() to return to the previous activity. How can I return to the previous activity?
2. I'm trying to run the above described activity from the run() function (from the timer class that execute the run() function every 10 seconds). When I do that, a runtime exception is raised. But when I start the above described activity from a button clicked (not from the timer) it works fine.
I am having trouble running my application as every time i try to run it the simulator gives me a an error.
I looked through the Documentation but I couldn't find anything on user created classes.
CODE:.................
I'm trying to think of a way on how to sync in between a local service and the main activity.
The local service has,
A thread with a socket connection that could receive data at any time.
A list/array with data.
At any time the socket could receive data and add it to the list.
The activity needs to display this data. So when the activity starts up it needs to attach or start the local service and fetch the list. It also needs to be notified if the list is updated.
I think I would need to sync my list somehow so the local service does not add a new entry to it while the activity fetches the list when connecting to the service.
I've configured local service under some app i wanna know how could i invoke methods on the activity, through the service in a synchronous way for example the service invoke a method inthe activity and waiting for for result(synchronous) from it.
View 2 Replies View RelatedI published an application that stores data in a local database.
Now I have to publish an update to this application to fix some little bugs, but I am afraid that downloading and installing the update will delate the local database associated with the previous version.
I would like to know how the update system works. Will installing an update completely delete all the apk, files, databases associeted with the previous version?
If so, how can I avoid this in my code?
I am creating a layout through code and want to add a View to that layout. The view which is to be added is defined in the xml file. Is there any way to use an View from xml before calling setContentView method. Because we can not call findViewById before setContentView.
View 2 Replies View RelatedI have a main.xml as the main view and another alert_dialog_text_entry.xml for one dialog when a button is clicked in the main.xml view. In the click handler of the button, the findViewById () can't work, the returned vaule is null, the code is like this:
CODE:...........
The alert_dialog_text_entry.xml:
CODE:................
I develop an application. This don't use activity class. only use service class..
I need method(findviewbyid). but service don't have this method.
I try to customize a tab and I write this code:
CODE:.......................
I create a dialog using this:
CODE:.................
Then I try to get the 'yes' button using this: Button yesButton = (Button)d.findViewById(R.string.btn_yes);
But I get null for my 'yesButton'.
Any idea why findViewById does not work? And if not, how can I get a reference to yes button of the dialog?
what would be the outcome of using findViewById when multiple child views have the same ID lets say for example when using a layout to dynamically produce multiples of the same control?
View 4 Replies View RelatedI have super.xml and a subset.xml.
...............
I get a null pointer exception at price.setText(data.getStrTotalPrice()); Very strange, name.setText(data.getStrDescription()); does not give a null pointer exception.
If you got:
CODE:........
where "widget28" is the name of your button, how can you pass this into the findViewById as a String? or get it from R class as a string?
I want to get the Button instance by string and not by the hard code R.id.widget28 reference.
trying to find some performance numbers for findViewById - need to convince to change bunch of the findViewById for the same widget to member variable with just one findViewById on create . Or may be i'm wrong and it's fine ?
View 6 Replies View RelatedI am having a problem where in the started Intent, the findViewById returns null. Is there anything special I should know about starting a new intent? It goes something like this for me:
//in the MainList class
Intent stuffList = new Intent(this, StuffList.class);
then in the new Stuff's constructor:...............
I have a class that is called when my app launches. public class MainActivity extends Activity implements NetworkEvent.
In this situation, list = (ListView) findViewById(R.id.list); works perfectly.
However if I then call a new intent via:
CODE:.........
where SimpleList is defined as: public class SimpleList extends ListActivity implements NetworkEvent then when I call
CODE:.........
From within the SimpleList class, list is null :(
How come? Both classes are within the same package.
Eclipse is marking findViewById(int) as undefined; it was doing the same thing for getResources(), but I was able to get around that by calling context.getResources() instead (as seen below) and can't seem to find a similar workaround for findViewById.
Here is the code:
CODE:.....................
Is there another package I need to import for findViewById?
Is it somehow possible that instead of:
Button btnNextWord = (Button) this.findViewById(R.id.btnNextWord);
Eclipse automatically generates for me something like:
Button btnNextWord = this.btnNextWord;
or
Button btnNextWord = R.id.getBtnNextWord(this);?
This is going to be a bit lame question. I have the following code:
CODE:.....
I have a TextView in my xml layout file. I'd like to get it and change my text when I click this button.
But I can't get it (the TextView) unless I make it as a value of a static member of this class and pass it to the constructor. I believe I am missing a big point here, so i'd be very thankful if you could explain how this is meant to be done ?
This code works fine if I move the findViewById call in to the Activity. Any hints as to why it doesn't work from inside the LearningView class? I've tried moving the TextView inside the com.example.LearningView tag but no joy. I'd prefer to get the TextView from within the SurfaceView subclass as I feel it's more logical to treat the TV as a "child" of the SV.
This is a contrived example I wrote to figure out the problem in a larger application, but the gist of it is the same, and the stack trace is basically the same.
For what it is worth, the findViewById call is returning null, which obviously threw NullPointerExceptions in some attempts to fix this.
As you can probably gather from my attempts I'm flying blind on this one.
Learning.java:
CODE:..........
main.xml:
CODE:..............
Stack trace:
CODE:......................