Saturday, June 15, 2013

Android Library as a .JAR file and accessing the resources in it

There was a new wave of discussions around possibility of packaging of the Android Library into a .JAR file and how to access resources in it. It is quite understandable, as current traditional solution, consisting of creating special Library Project and referencing such project from your main project, quite plainly, sucks. If you have multiple projects linked like this, your IDE will turn into crawling and you will constantly face breaks in this very fragile system.

What are our options to solve this problem ?

One possibility is to skip it altogether, and always copy all the files into the single project. It requires both discipline and good tracking system not to modify "library code" in two different projects, but it is manageable this way, and single flat project with no dependencies usually offers considerable speed advantages.

But it is not always possible to use this, especially when you want to package your code into "Library" to be used by the third party. Google is well aware of this problem and in the latest iteration of its ADK (based on Idea and Gradle) plans to introduce a new system that would allow similar mechanism. But their choice to introduce yet another archive format (although it is very similar to .JAR, with just different manifest file) is puzzling, and there is no guarantee this would work for this particular purpose, given the long history of failures of the ADK team. Also there are cases, where .JAR is the only option. We were exactly in the same position as our ObjectForms library would be best served as .JAR library thus we spent considerable amount of research on the matter in order to have a working solution.

Lets have a look what it takes to create Android .JAR library and how to access the eventual resources packed into it. There are many myths around this, with some people claiming "it is not possible at all", some of this information is inaccurate.

First part of the series will cover options in creation of a .JAR file, stay tuned for a link appearing here.

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