Can not compile enums in Eclipse

问题:

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

1. The type java.lang.Enum cannot be resolved. It is indirectly referenced from required .class files
2. 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;
  }
}

回答1:

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

回答2:

1. Go to properties of project with the build error (right click > Properties)
2. View the "Libraries" tab in the "Build Path" section
3. 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)
4. Remove the "JRE System Library"
5. Hit "Add Library ...", Select "JRE System Library" and add the appropriate JRE for the project (eg. 'Workspace default JRE')
6. 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 ...

回答3:

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 .