Can reflection be used with methods that belong to

Question

I am developing an app which has to support at minimum level 10 sdk. Today, I was coding when I came across a method setLayerType() which I need to use. But this method is introduced in API level 11. So, I used a workaround and used Reflection to use this method.

So, my question is, won't my application still crash on device which runs on API level 10?

This question came to my mind because, even though I am using Reflection here, still, I am calling a method that was introduced in API level 11. Will this method run successfully when I run my app on Android devices that run on API level 10 or will it crash?

As stated in source, the method will run independent of OS level. But, why should it run successfully on API level 10 device which is still using Android.jar of API level 10 and that file doesn't even contain this method?

I tried to search it but couldn't find an explanation.

P.S. I wanted to test it on a device with API level 10, but as building full app will take some time, so it is not possible to test app on API level 10 device right now.

Answer 1

You don't even need Reflection for that. Just specify your target sdk as high as possible, and your min sdk as low as it is now. Then, before calling a method that was introduced after the min version, just check which api version your app is running on:

if (android.os.Build.VERSION.SDK_INT >= 11) {
    //Your code here
}

Trying to use methods that were introduced in a later api version will lead to a crash otherwise, whether you call it using Reflection or not.

Answer 2

No, of course the app will crash if you call a method that is not present in its API level. This is true whether you call by reflection or not.

The point of reflection is that you choose whether or not to call it based on the API level. Compare http://developer.android.com/reference/android/os/Build.VERSION.html#SDK_INT to http://developer.android.com/reference/android/os/Build.VERSION_CODES.html in your code and only proceed with the reflective call if the SDK number is high enough.

The point is that you isolate code with bytecode references to any method or constant or class that's not present in all API levels into a separate class that is only loaded by reflection.

Here's an example of some utility code I created just to manage this kind of thing; it loads one or the other implementation of an interface based on API level:

https://code.google.com/p/zxing/source/browse/trunk/android/src/com/google/zxing/client/android/common/PlatformSupportManager.java?spec=svn2361&r=2361

EDIT: @FD_'s answer works too which surprises me. Reflection is safer, but much more code. And it seems like the reflection approach is in fact unnecessary on recent, if not all, Android JVMs.