Android :: Singleton Wrapper For Context
May 3, 2010
I'm considering creating a singleton wrapper for a Context so my model objects, if necessary, can open and read from a database connection. My model objects do not have access to a Context, and I'd like to avoid needing to pass a reference to a Context from object to object.I was planning to place into this singleton a reference to the Context returned by Application.getApplicationContext(). This singleton object would be initialized in my custom Application instance before anything else would need to or have a chance to use it.Can anyone think of a reason to not do this?
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Oct 10, 2010
I often run into the following dilemma: I need some singleton-like object in my app (typically some central manager-like thing) and this object needs a context for various things. This means that I either have to pass a context to all methods needing one or have some sort of init-pattern to the object. Neither is pretty I think. What is the correct way of doing this? Or is this simply (even the definition of) a Service?
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Apr 6, 2010
I am attempting to create a wrapper class for Google Android's Text-To-Speech functionality. However, I'm having trouble finding a way to have the system pause until after the onInit function has finished. Attached at the bottom is something of a solution I created based on what I found here: http://stackoverflow.com /questions/ 1160876/android-speech-how-can-you-read-text-in-android However, this solution does not seem to work. Any thoughts on why this might not be working, or what would be a good idea in order to make sure that any Speak() calls happen after my onInit() call? public class SpeechSynth implements OnInitListener
{private TextToSpeech tts;
static final int TTS_CHECK_CODE = 0;
private int ready = 0;
private ReentrantLock waitForInitLock = new ReentrantLock();
SpeechSynth( Activity screen )
{ ready = 0;
tts = new TextToSpeech( screen, this );
waitForInitLock.lock();
public void onInit(int status)
{ if (status == TextToSpeech.SUCCESS)
{ready = 1;
} waitForInitLock.unlock();
}public int Speak( String text )
{ if( ready == 1 )
{tts.speak(text, TextToSpeech.QUEUE_ADD, null);
return 1;
} else
{ return 0;
} I have been able to make it so that I can pass a string of text through the constructor, then have it played in the onInit() function. However, I would really like to avoid having to destroy and re-create the whole text-to-speech engine every time I need to have my program say something different.
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Mar 9, 2010
I am developing an Android Application for which i would be using a high level SQL-Lite Wrapper. Can anyone suggest me a high level wrapper for SQL Lite.
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Apr 2, 2010
I am relatively new to android but a very big fan. I'm not a stranger to development on handheld devices, since I have some experience with Symbian OS, both 3rd and 5th edition, using C++. Implicitly I prefer development using this language, so I was a little disappointed when I heard that the preferred API for Android is in Java, though the core of Android is linux.
I read in a book that at least some parts of the Java API for android is just a wrapper for C/C++ frameworks. My question to you:
Would it be possible to develop applications in C++ without going through the Java wrapper? As far as I know, the NDK does not provide support for all the features within Android ( for example SQLite, though it's heart is not java ).
I believe it is not impossible ( I've seen some demos of early stages of Qt ported on Android ), but I'm not sure how to approach this. Would these applications be installable via an apk?
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Jun 10, 2010
I'm trying to write a wrapper around Android's AdbWinApi.dll.
I've run dumpbin on the DLL and found a number of entry points. The problem is I don't really understand how to use those entry points and tie them up to the ADB API.
What is a good starting point to write this wrapper?
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Jan 3, 2010
When I first ran across PhoneGap, I was excited because I envisioned simply dropping in the URL of a mobile site and simply updating the mobile site to use the devices capabilities when available.
Alas, it seems it is not that easy.
From what I understand (and I could be incorrect), any HTML/JS access to the device's hardware is limited to local 'pages'. So essentially create a HTML/JS local 'web' app to access the 'real' mobile web app by AJAX like calls. It seems a little redundant (at least to me) when the point is to simply extend the interface an existing mobile site.
Not trying to knock PhoneGap here, just wondering if there's a similar framework that allows a remote site to access the phone's hardware directly. Or if I've missed how that can be done with PhoneGap.
(Sure, I know "allows a remote site to access the phone's hardware directly" sounds scary - but the URL is hard-coded in the app, and HTTPS could provide authenticity. Of course, security is probably why this isn't supported by PhoneGap.)
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Apr 9, 2010
Android has such concept as a Service. It makes sense for interprocess communication. But if I need this service from Activities running in the same process regular singleton seems to be more convenient. No need to register, to bind. Are there any benefits to use service in the same process?
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Aug 25, 2010
I'm quite new to Android development. When is it a good idea to create an Android Service instead of just using a simple Singleton class?
Take, for example, the data layer downloading information feeds from the internet. Using a Service seems too much for some cases but sometimes I might need access to a Context so I'm a little unsure about how to design the app.
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Feb 11, 2010
I'd like to know if it's possible to create a Singleton Service throughout an application ? Let's say I'd like to cerate a Service to play some mp3... I'd like it to be a Singleton, we don't want two mp3 tracks playing through each other (well maybe some would want that, but in my case I'm not making a DJ app) :P Also this Service should be somewhat dynamic as in there should be some interface so that I can stop, pauze and play the mp3 file/ stream. Now I have a couple of questions : - is this feasible ? - should I be using a Service or something else ? - how can an interface be set up in between an application and a service so that I can start, stop, pauze stuff ? - can there be something like a Singleton Service?
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Mar 23, 2010
I have a singleton class and I am using it to access databases. I would like to know how it would behave if I use the same from my remote service class which runs as a separate process. Will it create a new instance in that process or will it use the instance from the other process?
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Aug 17, 2010
I'm adapting Image Downloader from Google Android blog. I want ImageDownloader to be singleton since I'll be using it in multiple places in my application. I want also to be able to manipulate Bitmaps using different Strategies (eg. produce transparent bitmaps).I want to be able to use ImageDownloader in one activity and set transparent bitmaps, and in another use the same ImageDownloader but get black&white bitmaps using different strategy object.
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Sep 1, 2010
I have a singleton in an activity. When I end my application (like pressing back button), and start it again after some time, the singleton is not recreated, but is holding previous state. Singleton is not destroyed if the application is destroyed? Do I have to null its static members in onDestroy() to avoid memory leak.
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Dec 14, 2009
Is the AudioTrack fundamentally designed to be a singleton? Methods on the OnPlaybackPositionUpdateListener receive just one argument, which is the AudioTrack itself. And since the AudioTrack does not have getTag/setTag methods I don't see any way to distinguish among multiple AudioTracks in the OnPlaybackPositionUpdateListener methods short of keeping track of references. So, if it's so why it's not implemented as a singleton? Any thoughts. I am trying to implement concurrent use of the AudioTrack. Anybody has any experience with this approach? Am I wasting time?
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Sep 1, 2010
On Wed, Sep 1, 2010 at 1:19 PM, siva <sivaraj.r...@gmail.com> wrote: > I have a singleton in an activity. When I end my application (like > pressing back button), and start it again after some time, the > singleton is not recreated, but is holding previous state. Singleton > is not destroyed if the application is destroyed?
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Mar 17, 2009
In order to communicate with the server I need a huge global object (class with some hashmaps). all my activities (about 10) need that huge global object. which options do I have? I am thinking about passing the object using intends and about the possibility to make the object a singleton. using the db will be much too slow.
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Sep 17, 2010
I have a singleton which stores some prudent information about the user of my application. At the moment, it stores the user's login and the user's location.The location is found via a Service. At the moment, the Service references my singleton directly to stuff the longitude and latitude into it. I would like to use a Broadcast Receiver to send a broadcast that the singleton hears and uses to update the values, instead. However, to register the Broadcast Receiver, I need a Context in my singleton. What is the slickest way to achieve what I'm wanting. Is Broadcast Receiver possibly not the appropriate object? Also, what problems am I looking at with using a singleton? I assume that Android will possibly reclaim this memory at any given time (which would obviously be bad); so how can I prevent that? Would passing in the application's Context and storing it in a member variable thwart this? The Android documentation states: "But, the life cycle of a static is not well under your control; so to abide by the life-cycle model, the application class should initiate and tear down these static objects in the onCreate() and on Terminate() methods of the Application Class," but I'm not entirely sure how to accomplish this.
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Mar 25, 2009
I have two services, both of them lies in separate apk, which run in same process. The two service share same jar file by <uses-library> method. The jar file implement a class, say "test", is a singleton. But I found that two instance of test is created under this case, could anybody give me some tips? I want to ensure it's singleton. Code...
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Nov 15, 2010
Let me give you the scenario.
Say that my first Activity that loads up, also creates a thread, which will run indefinitely in the background.
Now, if I move to another Activity, I assume that the thread that I initially created in the main activity will continue to run.
So, now to my main question - in order to manage this background thread from other Activities, is it safe to store a reference to that thread in a singleton object?
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Sep 3, 2010
Can I pass a singleton class's object from one activity to another activity using intent? I am using singleton class as image class img = image class.get Instance();, so i need the img instance for another activity, how can i pass an object instance in Android.
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Nov 24, 2010
It would be nice if StackOverflow had a section where we could post tutorials like mine so that I can answer literally hundreds of questions that have been asked here with a single blow. See... every day I read questions about how to pass complex objects between activities, how to save state so that your app can resume after orientation change, how to update listviews when the data changes, etc, etc. Here is the second part of a tutorial series I posted on my blog... I hope that you actually read it... because I haven't seen any examples like it anywhere... and it has changed how I think about developing for Android across the board. The question is... is there a downside or negative affect of developing like this?
Beyond Smart Lists - How Observable Singletons change the game. Please read through both of these tutorials carefully... I will answer any questions about it here that I can... I really want to know what you think about this and if it might solve issues for you. NOTE TO MODERATORS: there are no advertisements of any kind on my blog.. so don't just close this because you think I am spamming somehow... I am not going to duplicate my post here.
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Jan 21, 2010
How can I launch a contextmenu from a contextmenu? I'm trying to replicate the MediaPlayer action that happens when you long click a song, then click "Add to playlist" in the resulting contextmenu. When you click that menu item, another contextmenu pops up with "Add to playlist" as the title, and "Current playlist", "New", and however-many-playlists-you-have defined after that.
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Aug 3, 2010
If an Activity is a singleton in practice, I think I can gain some efficiency by declaring appropriate members "static", with zero risk. Yes?
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Jul 19, 2010
I'm confused about the concept of the Context class. I see that it's a base class of Activity, but the Android docs also mentions the Context storing global information about the app environment. So in my app which has 3 activities, does that mean I have 3 distinct Context objects, or do they actually refer to 1 entity? Also, what is the lifetime of a Context object- does it live until the last component of this activity's process is garbage collected?
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Nov 24, 2010
i have got a stupid question to ask. I created a custom ContextMenu. But when i call the menu, the menu displayed will also have the default menu added in. Is there anyway for the default ContextMenu not to appear as well?Code requested: @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo)
super.onCreateContextMenu(menu, v, menuInfo);
MenuInflater inflater = getMenuInflater();
menu.setHeaderTitle("Recipients");
inflater.inflate(R.menu.menu_contacts, menu);
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Jan 4, 2010
Is there a way to get the current Context instance by using a static method? I'm looking for that way because i hate saving the context instance each time it changes.
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May 15, 2009
When you are developing on an application level(Services, Activities) you always get this Context reference automatically. But what if I am on a lower level and developing a program started with app_process, how can I get hold of a Context then? Its a huge part of the API that need this context. What the proper way to create a Context instance?
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Jun 12, 2009
In an Android app, is there anything wrong with the following approach..
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Jul 19, 2010
What is the lifetime of an app's global android.content.Context object? Does it last until the last component of the app is terminated by the Android runtime?
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Jun 18, 2009
Hi! I use dialog with multipleChoiseItems. Is there any way to create context menu for list of the items?
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