In the process of updating and refactoring an old Android project I unwittingly changed a Project configuration option (the “Is Library” option) that lead to my resource file being generated differently. E.g

Before

[java] public final class R { public static final class id { public static final int button1=0x7f090001; public static final int button2=0x7f090002; public static final int button3=0x7f090003; } } [/java]

After

[java] public final class R { public static final class id { public static int button1=0x7f090001; public static int button2=0x7f090002; public static int button3=0x7f090003; } } [/java]

A subtle change indeed but one that caused the following compiler error for each line

case expressions must be constant expressions