JDK 1.7编译器无法识别通用类

Question

I have a class which uses a class from Eclipse OSGI jar (org.eclipse.osgi_3.7.2.v20120110-1415.jar) and which is well compiled within Eclipse IDE and it's compiler. But if I try to compile this class with Ant and JDK 1.7 compiler, the compiler outputs these errors:

[javac] /data/ant/sw_jdk1.7/test-Java7/com.tsystems.favbg.ui.core/src/com/
        tsystems/favbg/ui/core/job/AbstractLoader.java:24: 
        error: type CopyOnWriteIdentityMap does not take parameters
[javac]     private final CopyOnWriteIdentityMap<LoaderListener, String>
            eventListenerMap = new CopyOnWriteIdentityMap<>();

and

error: cannot infer type arguments for CopyOnWriteIdentityMap;
[javac]     private final CopyOnWriteIdentityMap<LoaderListener, String> 
            eventListenerMap = new CopyOnWriteIdentityMap<>();
[javac]   reason: cannot use '<>' with non-generic class CopyOnWriteIdentityMap

Obviously javac does not recognize the class as using generics. But when I open it with Java Decompiler generic parameters are well recognized. Does anybody know this problem and have a solution?

Answer 1

I would say that the problem is in the way that you are using CopyOnWriteIdentityMap class. I'm assuming that you are using this class:

  org.eclipse.osgi.framework.eventmgr.CopyOnWriteIdentityMap

If you look at the javadocs , you will see that it is not a generic class. I also get the impression (from its package location) that it is not intended to be a general purpose utility class.

Perhaps you are using a different version of the JAR when you are compiling in Eclipse ... one that is a generic class. Either way, the compiler you are using via Ant thinks it is not generic.

Answer 2

I am finding discrepancies when reading a certification book for SCJP based on JDK 1.6, and, trying to write (copy and paste) code, compiling within JDK 1.7.

Perhaps, I am making the same mistakes all over, however they seem hard to comprehend. For example see my posts at http://www.coderanch.com/forums/posts/list/80/467890#2679297 . I am not an expert, however, I find the curriculum of Angelika Langer (http://www.angelikalanger.com/Publications.html), to be appealing for consulting, given the tutorials available on the website relating to Java Generics.

What is your advice on the matter?