i developed an app that contains a lot of activities and different application within the same app and they are all interconnected by sending different intents within it to function the whole app, however they still do different things and i can elimante one without hurting the other and causing the whole app to crash. so if i want i can divide them to be stand alone apps.
My question is this:
Can i have one app that download the basic activities and if a person want a specific activity they can download it (Eg: you download a game and that game includes a different set of levels that can be downloaded by pressing a button hence downloads that particular set of levels.)?
Forgive me if I misunderstood you, but are you talking about creating one big app that consists of many smaller apps, but rather than being all bundled in the beginning, a user can download each one as a module?
If it's this, it's not impossible, but not possible in the sense that I think you're hoping for.
Your one big app will still need all the necessary code and xml files because these need to exist when compiling. But what you can do, which is similar to what games do is to offer downloadable content that isn't code. Essentially, these are resources such as media files, text, or other data of the like.
Those data can be downloaded separately without affecting your app and it helps reduce the size of your app. However, the actual functionality of each individual app will still need to be within your app, but hidden until it's downloaded.
Typically, it's more common to just bundle it all together such as a Measurements app, or to have them as individual standalone apps such as Google Docs, Sheets, and Slides.
You're basically describing how a browser/website works.
If you really wanted to wrap this up as a mobile app, you could use webviews.
Related
I'm working on an app that needs to support a large number of languages. Instead of bundling all languages in the app resources, I want to be able to download the language when the user selects a new language from the settings menu.
The Facebook mobile app does this very well. If you are logged in, go to settings> languages > switch language > pick a different language.
I think Facebook are downloading these language resources, Because if i put my phone into airplane mode , it doesn't work ( prompted with try again, or use english as default).
Since the app resources can't be edited at runtime, i'm guessing Facebook are using a database to download the language , then load the translations from there?!
p.s i'm actually trying to do this in Xamarin...trying to understand the Facebook Android approach so I can implement it myself.
I don't know specifically about Facebook, but I know this technique is in use by some people -- I've seen presentations on similar setups from other companies. There are a couple of obvious benefits:
Reduce overall app size by not bundling 30 languages worth of strings.
The ability to improve localized strings without forcing the user to download an app update.
Better data about what languages your users are using.
When I've seen in presented (again, this was not Facebook specifically), it worked much as you suggested -- user selects the preferred language, app fetches a string bundle from the server, then starts using it. Once the language is set, the app can even periodically refresh the localized string bundle to get updates.
However, there are some downsides to be aware of, especially if the localized strings change over time. It can make support tricky -- if a string has changed, a button (for example) might be called different things depending on exactly when the user was using the app. It also will really put pressure on your i18n strategy and QA to make sure the UI looks decent with strings that might be changing frequently.
If you download localization files you will not be able to use the default localization support within Android.
If you do go ahead with this strategy (downloading of localization files), you will need to create your own class to manage this or alternatively, search for a library which does this for you.
So I am using the Home sample to build an application that creates a second home screen for the user. The idea is to be able to have only one user account yet restrict certain access to chosen applications. I have managed to ensure that all of the applications are invisible in the XML yet I am struggling with how to change this to make certain apps visible.
Is it possible to write a whitelist of accepted apps for instance the preinstalled apps or child friendly apps for children who game using the android device and then put in a Java method to access this white list? This is the only way I can think to make it work.
If anyone knows the correct way can you please help.
Thanks.
Ok so I discovered how to do this.
In the home sample they provide a for loop in the Home.java file that covers all apps and displays them. It take a simple if statement to restrict the apps that can be viewed -
// for loop is here
if (info.activityInfo.applicationInfo.packageName.contains("com.android"))
//then the rest of the home sample is here.
Still very basic but provides me with a good enough UI so that kids cannot see apps I don't want them to.
I have a scenario which I think is pretty common in Android applications. I know partial attempts of solving the issue were made, but until now I have not stumbled upon the full implementation. I intend to try to implement such component and open source it afterwards, but I need your help in its design.
So basically my case is the following: I have list view showing image loaded from the web and text per each row. I want to lazily load the images, placing default for each image and substituting it with the real one only when the image is downloaded. I also want to keep image cache avoiding the need to download the images multiple times in short period.
Up to now I have found several implementations that are partially working including:
Tom van Zummeren's implementation of similar component with several well known problems
Jeremy Wadsack's refinement of the concept, which is more or less working
Lazy drawables source forge project.
I also saw several stackoverflow questions regarding the problem: 1, 2, 3
However I have one more requirement which makes my task a bit more complex: I allow the user of my application to affiliate himself with some of the images. I want to load the new images associated to the user whenever the user navigates to the home screen. From it he should be able to go see his images, even before they have all been downloaded and in this case again default placeholders should be visible (Note the cross screen transition). Such use cases are:
An app listing user's youtube videos
An app for facebook - consider the images of friends
An app serving news that supports user's favorites etc
Note that I want to start fetching the new data related to the user on the home screen to provide better user experience. I will keep the user-related data stored locally forever.
The question
So my basic question is what approach should I use for the implementation of the image downloading? I know that the Android manuals say Service should be used only when I want to execute task even when application is not running. On the other side I will start the image downloading on the home screen and link the downloads to UI elements just when the user navigates to the new screen (Activity) - user-related list view and I do not know how to achieve that with AsyncTask (not that I have a very precise idea how to do it with Service either).
Any suggestion will be greatly appreciated, including links.
Universal Image Downloader is a good library which helps you to do image downloading in background with your settings.
It has so many features that you can implement at your own way.
I'm pretty much new to Android, but over the last two or three weeks I've managed to figure out most of its innards and how things work.
However, one thing is still bothering me - what's the basic difference between Activities and simple forms? Well, I know Android doesn't have such thing as a 'form', but by that I mean a fullscreen layout of elements that has an underlying class and all its functionality is executed in it, rather than in a process-wide class (Activity, to be precise).
As long as I understand, Activity is a separate process that's instantiated by OS to perform some actions that are basicly independent of the whole application. That also means that we can run only one of the application's activities, and it will still perform all of its functions without needing the whole application to be loaded. For example, if we have a movie player that can also convert movies from one codec to another, we can implement that functionality as a separate Activity so that other applications, like file managers, will also be able to convert movies between codecs using only that Activity, and not the whole application.
And that seems perfectly straightforward. The question is - why is everybody using separate Activities for functionality that cannot be separated from the application? In other words, people generally use Activities where I think simple forms within the same process would be more appropriate. For instance, I've seen people using a separate Activity for things like application settings, which obviously wouldn't be be launched outside the app itself, or editing application-specific data, which wouldn't be done outside the app as well, since the data to be edited should be selected from a list only known to the application.
Another example right from my experience - a unit converter application. It has a main menu with a GridView of units' categories, in each category there is a list of units and by clicking any unit we have a 'calculator' form for entering value that we want to convert. If I'd been doing that like everyone suggests I'd have three Activities - one for the main menu, one for the list of units and one for entering the value. But why? Why would I want to launch any of those three Activities separate from the application? If I'd want to launch main menu Activity - well, why not launch the whole application then? If I want just a list of units - again, just launch the whole application, it's not like some Facebook client is going to convert values between pressure units (since the list of units covers only one category at a time). And launching an activity for the calculator simply would not work, since it should return to the list to perform conversions and you'd have no list activity launched.
And anyway, even if I'm wrong and people use it wisely there's still an issue that Android SDK doesn't really provide any support for forms as I'm used to. Yes, there are things like ViewAnimator, ViewSwitcher etc. But all they do is switch layouts in their place, and that is hardly switching between forms as such. So the only choice to get close to that functionality at least is to use Activities. And we're back to the square one.
So to put it simply - am I missing something from the Android philosophy? Because I'm pretty sure that using a separate Activity (and a separate process as a result) for every single form in the application is an overkill. And if it really is and everybody knows that - why doesn't Android have any substantial form switching mechanism?
Thanks in advance for any clarification on this issue.
An activity isn't spawned in a separate process (unless you explicitly tell it to). Everything in your APK will be spawned in your process. Even if another application is using your Activity for whatever reason.
You can make your Activity "effectively" private to your application by not assigning any intent-filter to it in your manifest.
For the examples given, a form is equal to an activity. That isn't a universal statement as you delve deeper into Android, but for a beginner that's a decent analogy to make. Another common analogy is that Activities are more like web pages than traditional forms based UI.
Were looking into Android for writing a tablet based system. Part of the design is for the system to be as modular as possible. One aspect of this is to display any "STATUS" activities in a side view on the screen. It looks like I can use PackageManager queryIntentActivities() to find the activities that show status information. But, can I display these in a single view all at the same time (via a linear layout)? The activities would be installed in separate apk's (features).
Can this be accomplished using ActivityGroup? Is this even allowed in Android? Everything I've read implies that Activities take the whole screen or float on top. This implies only one activity can be active at a time where as the design I'm thinking of uses the activities more like widgets.
You should be to be able to do what you want with just one activity, plus multiple (background) Services (on different threads) for your status updates.
Don't worry, you can still package them in different apks. You'll just need to sign them the same way, and your apks won't even be sandboxed from each other, so they'll be able to share the same data and share the same memory footprint of just one apk.
Also, take a look at NotificationManager, I know you want to roll your own solution, and you can certainly do that if you want, but you could also just reuse/extend NotificationManager and save yourself a bunch of work.