FULL PRODUCT VERSION :
java version "1.7.0_03"
Java(TM) SE Runtime Environment (build 1.7.0_03-b04)
Java HotSpot(TM) 64-Bit Server VM (build 22.1-b02, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux medea 2.6.35-32-generic #67-Ubuntu SMP Mon Mar 5 19:39:49 UTC 2012 x86_64 GNU/Linux


A DESCRIPTION OF THE PROBLEM :
The EnumMap clone implementation does not clear the field entrySet. Therefore, any call to the method entrySet in a cloned map (with its entrySet initialized) ) will return a reference to the original entrySet instead of returning a new entrySet pointing to the new map instance.

This breaks the Map.entrySet contract which states " Returns a Set view of the mappings contained in this map"

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
This happens every time a EnumMap, which has its entrySet initialized, is cloned. All changes made to the new instance won't be reflected by the EntrySet returned by the entrySet() method.

Example:

import java.util.EnumMap;
import java.util.Map.Entry;


public class TestEnumMap {
    public enum Test {
        ONE, TWO
    }

    public static void main(String[] args) {
        EnumMap<Test, String> map1 = new EnumMap<Test, String>(Test.class);
        map1.put(Test.ONE, "1");
        map1.put(Test.TWO, "2");

        for (Entry<Test, String> entry : map1.entrySet()) {
            System.out.println(entry);
        }

        System.out.println("---------------");

        EnumMap<Test, String> map2 = map1.clone();
        map2.remove(Test.ONE);
        for (Entry<Test, String> entry : map2.entrySet()) {
            System.out.println(entry);
        }
    }
}

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
ONE=1
TWO=2
---------------
TWO=2

ACTUAL -
ONE=1
TWO=2
---------------
ONE=1
TWO=2


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.EnumMap;
import java.util.Map.Entry;


public class TestEnumMap {
    public enum Test {
        ONE, TWO
    }

    public static void main(String[] args) {
        EnumMap<Test, String> map1 = new EnumMap<Test, String>(Test.class);
        map1.put(Test.ONE, "1");
        map1.put(Test.TWO, "2");

        for (Entry<Test, String> entry : map1.entrySet()) {
            System.out.println(entry);
        }

        System.out.println("---------------");

        EnumMap<Test, String> map2 = map1.clone();
        map2.remove(Test.ONE);
        for (Entry<Test, String> entry : map2.entrySet()) {
            System.out.println(entry);
        }
    }
}
---------- END SOURCE ----------