Develop Reference

Android: Minimum API level requirement to use Google Vision API?

I'm working on an Andriod Studio project and I'm trying to use the Google Cloud Vision API. I've been trying to figure out if I can use it since my target sdk is level 15-25, but I can't find the minimum required sdk level anywhere in the documentation.
The only information relevant to this that I found was the only sample application on their website and it says under prerequisites "
An Android device running Android 5.0 or higher 1
That doesn't necessarily mean it doesn't work for lower API levels. Does anyone know what's the minimum requirement?

According to this link vision API depends on the Google Play Services which are curently available for Android 4.0 and above. So for now I think you can continue using the API for your min SDK version 15.
But on a long run there will be many more cool features that will added to lollipop and above only. So the question is, do you want support or quality? Either comprimise the quality for the devices which has 4.0 or focus on quality by building for 5.0 and above because soon devices below 5.0 are going to be obsolete.

Which Android APIs are enough to target maximum number of devices?

I am thinking to make an application but at the time I don't have API 21 and API 22 installed on my SDK due to some network problems and I'm unable to download any thing at the moment. I was wondering if I can make an app effective enough to target many devices without using API 21 and API 22.

Bilal, judging from your comments to others, I'm getting the impression that you don't fully understand how the API levels work in Android. Let me try and explain.
The minimum API level is pretty self-explanatory, as it refers to the minimum Android OS version that can run your app. You want to set this as low as possible to target the most devices. To determine which level you set depends entirely on your application. For example, if your app requires access to the Calendar APIs, your minimum API level would be 7, because that is when those APIs were introduced.
You almost always want to set your maximum API level to the highest possible. Google encourages this, because it allows you to take advantage of all of the new APIs that have been released. But what about the devices that are outdated? You can still enable backwards compatibility with those devices using the Support Library.
Finally, it is not necessary to download each and every API level in the SDK manager. You only need to download the most recent.

Upgrade Android Api Version

I have an Android device, apparently with API Level 10.
I'm developping an Android Application and I need to test it on API level 12.
I don't know much about Android and API levels, so my question is: Can I update my device to a higer API level ? (it says no New version available, aren't hier APIs considered new version?)
(I can't use the Emulators, as they really need a huge amount of ressources to start.)
Alternatively, is it possible to test the following code, on my API Level 10 device ?
UsbManager manager = (UsbManager) this.context.getSystemService(Context.USB_SERVICE);
I have the following warning:

Yes higher API levels = latest releases.
http://en.wikipedia.org/wiki/Android_version_history#Version_history_by_API_level makes the correlation between API and version number (2.3.4).
You should work with a device supporting latest api and high resolution because many of your users might have that and you NEED as a developer to see and test your work on these platforms.
Get yourself a nexus phone, you can upgrade these to the latest Android version.
Android version release : Google releases it --> manufacturers and Telecom Carriers checks and adjust the release before making it available to you. Hence, for old phone, the manufacturers and carriers don't make the effort and you are stuck to old versions.
If you do no want to or if you cannot find a more recent handset, you can install a custom ROM to try to reach API 12. But in any case, if you start developing, you ll need good handset soon.
good luck

You can try to see if there is a custom rom for your device that is of a higher api version. But this won't accurately test your app because there is probably a very good reason that a newer operating system was not made available for your device. As such, your app and the SDKs in the new API will probably not be able to make use of the hardware resources available, and you won't get an accurate representation of your app's performance.
You mentioned you can't use emulators but have you considered Genymotion's emulators? Although it is resource intensive it is better than Google's emulators and is faster than actual devices.

Assuming your using Eclipse ADT. You DONT have to update your device to level or API 12. All you have to do is specify the minimum required SDK, which is API 8 in most Eclipse ADT setups. and set your target SDK to API 12. That way your app will run on devices from API 8 through to API 12 Including you device. FYI the latest API is now 19 (Android 4.4) Hope this helps.

Android Compatibility Issue

I am working on an android application that uses Google Maps (Google API). At this moment it's just a simple map with a compass, and it gets the address of a location the user clicks. The problem is as follows:
The min SDK version : API level 8
Target SDK: API level 14
As I think, this should work properly on the range from 8 to 14 inclusive. But it only works properly on API level 14. I tested the app on Android 2.3.3 (API 10) the compass is missing, and the address functionality is not working either.
To be clear, the question is:
How can compatibility be done right?
Thanks in advance
Note: I am using an emulator (on Eclipse) and not a real device.

Emulators have a lot of trouble with the Google Maps API. To do any real testing with Goole Maps API you should have a real device.

What does API level mean?

I am wondering what exactly API level means. I couldn't seem to find an answer by searching on Google.
Could anyone please explain what the term API level means?

This actually sums it up pretty nicely.
API Levels generally mean that as a programmer, you can communicate with the devices' built in functions and functionality. As the API level increases, functionality adds up (although some of it can get deprecated).
Choosing an API level for an application development should take at least two thing into account:
Current distribution - How many devices can actually support my application, if it was developed for API level 9, it cannot run on API level 8 and below, then "only" around 60% of devices can run it (true to the date this post was made).
Choosing a lower API level may support more devices but gain less functionality for your app. you may also work harder to achieve features you could've easily gained if you chose higher API level.
Android API levels can be divided to five main groups (not scientific, but what the heck):
Android 1.5 - 2.3 (Cupcake to Gingerbread) - (API levels 3-10) - Android made specifically for smartphones.
Android 3.0 - 3.2 (Honeycomb) (API levels 11-13) - Android made for tablets.
Android 4.0 - 4.4 (KitKat) - (API levels 14-19) - A big merge with tons of additional functionality, totally revamped Android version, for both phone and tablets.
Android 5.0 - 5.1 (Lollipop) - (API levels 21-22) - Material Design introduced.
Android 6.0 - 6.… (Marshmallow) - (API levels 23-…) - Runtime Permissions,Apache HTTP Client Removed

API level is basically the Android version. Instead of using the Android version name (eg 2.0, 2.3, 3.0, etc) an integer number is used. This number is increased with each version. Android 1.6 is API Level 4, Android 2.0 is API Level 5, Android 2.0.1 is API Level 6, and so on.

An API is ready-made source code library.
In Java for example APIs are a set of related classes and interfaces that come in packages. This picture illustrates the libraries included in the Java Standard Edition API. Packages are denoted by their color.

The API is the android platform that make up the core language that
you will use when developing, and as you get the API version higher
the SDK tools should also be updated (which are the tools for
developing and debugging).
You should also take into account the market and how many devices
will support my selected API and choose the lowest API target
possible for your app to adapt more devices.