Can not compile enums in Eclipse

Question

While trying to introduce enums in my Android project in Eclipse, I encountered with the following problem: Compiler says:

The type java.lang.Enum cannot be resolved. It is indirectly referenced from required .class files
The type Enum is not generic; it cannot be parameterized with arguments

I work under Ubuntu 10.04 and use Eclipse v.3.5.2. Tried to use both Java 6 OpenJDK and Java 6 Sun, but without success.

Can anybody help me to sort out with this issue?

Here is the code:

public class MyClass {

  public MyClass() {
  }

  ...

  enum MyEnum {
    CONST1, CONST2, CONST3;
  }
}

The code looks correct. The semicolon at the end is even optional. — Shervin Asgari, Sep 28 '10 at 08:42

Aaron Digulla · Answer 1 · 2015-04-24T08:29:07.127

37

Open the properties for the project, select the page "Java Compiler" and set the "Compiler Compliance level" to "1.5" or better.

Project properties page for the Java Compiler

edited Apr 24 '15 at 08:29

answered Sep 28 '10 at 08:41

Aaron Digulla

Unfortunately I can't set "Compiler Compliance level" to "1.5" because I use @Override annotations for interfaces that is forbidden for 1.5 – Artem Sep 28 '10 at 08:52
@Artem, @Override is allowed in JDK 1.5 – Buhake Sindi Sep 28 '10 at 09:04
@Artem: If you can't set the compliance level to 1.5, you can't use enums because they are only allowed in Java 5. – Aaron Digulla Sep 28 '10 at 09:06
Thanks, Aaron, I thought if it's allowed in 1.5, then it's definitely allowed in 1.6. Please take a look: http://mindprod.com/jgloss/enum.html – Artem Sep 28 '10 at 09:16
Magic. Several times switched between 1.5 and 1.6 with full rebuild and now enums are compiled fine with 1.6. – Artem Sep 28 '10 at 10:08
1

@Artem: Sorry, I though it was clear that enums are allowed *since* Java 5 (which includes Java 6). Of course, they should work with Java 6 unless you have set the class or source compatibility to 1.4 or less. – Aaron Digulla Sep 28 '10 at 12:55
2

Thanks Aaron. it was definitely bug in Eclipse - probably because of other warning/errors – Artem Sep 28 '10 at 13:24

score 3 · Answer 2 · edited Apr 07 '16 at 22:31

Go to properties of project with the build error (right click > Properties)
View the "Libraries" tab in the "Build Path" section
Find the "JRE System Library" in the list (if this is missing then this error message is not an eclipse bug but a mis-configured project)
Remove the "JRE System Library"
Hit "Add Library ...", Select "JRE System Library" and add the appropriate JRE for the project (eg. 'Workspace default JRE')
Hit "Finish" in the library selection and "OK" in the project properties and then wait for the re-build of the project

Hopefully the error will be resolved ...

score 0 · Answer 3 · answered Feb 07 '12 at 17:20

Close project the project with the error.

Open a different project and launch in emulator. Close the alternative project.

Open the original project with the error which should no longer be evidenced.

Don't know why it works or if actually launching the app is necessary but it clears the error .

3 Answers3