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Editorial Team
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Asked: 2026-05-26T08:28:20+00:00

PREAMBLE: this question is quite obsolete, it was written when the preferred Android dev

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PREAMBLE: this question is quite obsolete, it was written when the preferred Android dev environment was Eclipse with the Android plugin.

I had a Java Android project for a while. Today, I’ve updated the Android dev tools to the Google’s latest. And the project broke – I get a bunch of "case expressions must be constant expressions" compilation error messages.

Turns out that the R.java file is being now generated differently. Formerly, it would have a bunch of

public static final int MyID=0x12340000;

statements; now, it looks (after a clean/rebuild) like this:

public static int MyID=0x12340000;

final is gone. So all switches on resource IDs that I had (and I had a few) are wrong. What happened, please? Is it just me? What’s the rationale here? Is it documented anywhere? Can I bring final back somehow?

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1 Answer

  1. Editorial Team

    This happened about yesterday, when the SDK/ADT 14 got released:

    As of ADT 14, resource constants in library projects are no longer
    final. This is explained in greater detail in http://tools.android.com/tips/non-constant-fields

    There’s a quickfix available from ADT 14: http://tools.android.com/recent/switchstatementconversion

    To quote from the rationale:

    When multiple library projects are combined, the actual values of the
    fields (which must be unique) could collide. Before ADT 14, all fields
    were final, so as a result, all libraries had to have all their
    resources and associated Java code recompiled along with the main
    project whenever they were used. This was bad for performance, since
    it made builds very slow. It also prevented distributing library
    projects that didn’t include the source code, limiting the usage scope
    of library projects.

    The reason the fields are no longer final is that it means that the library jars can be compiled once and reused directly in other projects. As well as allowing distributing binary version of library projects (coming in r15), this makes for much faster builds.

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