How to deal with deprecated classes in Android to keep compatibility

Question

I am getting back to work on an app I worked on a while ago, when I had everything built around Android 2.2 Froyo.

I have updated my SDK for the latest APIs and noticed that the ClipboardManager features I was using are deprecated. I updated the code to use the newer ClipData model and tried it out on my Froyo phone and, of course, I get a NoClassDefFoundError in the new code.

I've had a look around SO and haven't found any real discussions of general strategy for maintaining backwards compatibility.

I'm not entirely sure how I should handle this and other situations where the API differs, because I want users of all versions to be able to use my app.

Should I be doing a check as follows?

if(version == old){    use old API; } else {    use new API; } 

If so, I have deprecated code in my class and Eclipse will have the warning there forever.

On the other hand, I could just build against an old version of the API and hope that new versions will handle it okay. But then I run the risk of building against buggy or low-performance code when a better alternative is available.

What is the best way to deal with this?

Answer 1

You can do that (checking the API version).

You can also use reflection to call the newer classes.

I wouldn't worry about using deprecated methods as all Android versions are backwards compatible, saying that you want to watch when things are for 3.0 Honeycomb as these are a little different.

Here's an explanation of how to use reflection: (yes it's been on SO before, so maybe search for reflection)

http://www.youtube.com/watch?v=zNmohaZYvPw&feature=player_detailpage#t=2087s

I'm looking at making the project this is in available but until then here's some code:

(You could do this in a class that extends Application i.e. one time setup)

 public static Method getExternalFilesDir;      static {             try {                     Class<?> partypes[] = new Class[1];                     partypes[0] = String.class;                     getExternalFilesDir = Context.class.getMethod("getExternalFilesDir", partypes);             } catch (NoSuchMethodException e) {                     Log.e(TAG, "getExternalFilesDir isn't available in this devices api");             }     }  

Now getExternalFilesDir() is only available on API level 8 or above, so I want to use this if they have (Froyo), but otherwise I need another method.

Now I have my test for the method I can go ahead and attempt to use it:

  if(ClassThatExtendsApplication.getExternalFilesDir != null){             Object arglist[] = new Object[1];             arglist[0] = null;               File path = (File) ClassThatExtendsApplication.getExternalFilesDir.invoke(context, arglist);            // etc etc   } else {       // Not available do something else (like your deprecated methods / or load a different class / or notify they should get a newer version of Android to enhance your app ;-))   } 

Hope that helps and shortcuts a lot of googling :-)

P.S. if in the else you want to use your deprectated methods still, just add the @SuppressWarnings("deprecation") annotation above it, This will get rid of the warning and you have done it for the right reasons as you are using the latest API's when possible.

Answer 2

Here is an example:

import android.os.Build;  public static int getWidth(Context mContext){     int width=0;     WindowManager wm = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);     Display display = wm.getDefaultDisplay();      if(VERSION.SDK_INT > VERSION_CODES.HONEYCOMB){                            Point size = new Point();         display.getSize(size);         width = size.x;     }      else{          width = display.getWidth();  // deprecated, use only in Android OS<3.0.     }      return width; }  

as you can see the section of code:

  if(VERSION.SDK_INT > VERSION_CODES.HONEYCOMB){                                Point size = new Point();             display.getSize(size);             width = size.x;         }  

is only available for Android 3.0 and later versions, if you want this code available at least for Jelly Bean (Android 4.1) use:

  if(VERSION.SDK_INT > VERSION_CODES.JELLY_BEAN){                                Point size = new Point();             display.getSize(size);             width = size.x;         }  

VERSION.SDK_INT The user-visible SDK version of the framework; its possible values are defined in Build.VERSION_CODES.

More info about: Build.VERSION

And you can see the VERSION_CODES constats here: Build.VERSION_CODES