by Malcolm Rowe

Making Eclipse show Android’s source

The Eclipse support for Android development is pretty good, but one slight annoyance is that the source for the Android SDK classes isn’t available by default.

A screenshot of Eclipse
showing disassembled Java bytecode instead of the Android android.app.Activity
No source :-( (zoom)

Fortunately, there’s a fairly straightforward process to fix this.

First, get hold of the source JAR for the SDK. What’s that? We don’t appear to make a source JAR available? That’s annoying.

Well, hopefully that will be fixed at some point. In the meantime, you can either download one that someone’s prepared (that’s apparently for something approximating 1.5r2 — but note that I haven’t checked how correct it is!), or you can produce your own from the git repository, from a tag of your choice.

Once you have a source JAR, you’d normally expect to just attach it directly to the library in Eclipse, but that doesn’t work with the Android SDK: Eclipse says “The JAR of this class file belongs to container ‘Android 1.5’ which does not allow modifications to source attachments on its entries.”

Which is a roundabout way of saying that the source path is fixed. If you open up the Eclipse project properties dialog, change to the Java Build Path page and Libraries tab, then expand the ‘Android 1.5’ library container and then the android.jar file (phew!), you’ll see the ‘Source attachment’ option, which shows where the source is expected to be.

A screenshot of Eclipse showing the Java Build Path dialog.
The Java Build Path dialog (zoom)

For the Android 1.5 SDK, this is SDK Location/platforms/android-1.5/sources (and presumably similarly for the Android 1.1 target), where SDK Location is the path set in the workspace preferences’ Android page. Note that the 1.0 SDK (which only supported the 1.0 target, of course) just appends the string sources to the SDK Location, on the assumption that the SDK location ended with a trailing slash. (This should only be something to look out for if you need to target 1.0; I’m pretty sure it was fixed in the plugin provided with the 1.1 SDK.)

There are two ways to put the source JAR into the right place. The conventional way is to create a directory called sources/ under platforms/android-1.5/ (or 1.1), and then unzip the JAR (which is just a ZIP file) into that directory. However, although sources doesn’t have an extension, Eclipse doesn’t actually require it to be a directory, so a simpler way is just to rename your source JAR so that it’s called sources, and move it into the relevant directory.

Once you’ve moved the file or files into the right places, you just need to get Eclipse to take note of it. I found that just restarting Eclipse was enough, but if that doesn’t work you could always try refreshing the project, or closing and re-opening the project via the context menus.

A screenshot of Eclipse
showing the source to the Android android.app.Activity class.
Source :-) (zoom)

19 June 2009