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javagenericsenumsjava-6

java generics in action

I have the following code (java se 6):

import org.javatuples.Pair;

final SortedMap<Pair<AbstractEnum<?>, String>, AdapterObject> myMap = 
         new TreeMap<Pair<AbstractEnum<?>, String>();
myMap.put(Pair.with(SubTypeEnum.ITEM1, StringUtils.EMPTY), new AdapterObject());

AbstractEnum and SubTypeEnum are just:

public final class SubTypeEnum extends AbstractEnum<SubTypeEnum>
...
public abstract class AbstractEnum<T extends AbstractEnum<T>> implements Comparable<T>, Serializable

Now, the compiler says:

The method put(Pair<AbstractEnum<?>,String>, AdapterObject) in the type Map<Pair<AbstractEnum<?>,String>,AdapterObject> is not applicable for the arguments (Pair<SubTypeEnum,String>, new AdapterObject())

Any ideas how I can fix this?

Solution

  • Change the declaration to:

    final SortedMap<Pair<? extends AbstractEnum<?>, String>, AdapterObject> myMap = 
            new TreeMap<Pair<? extends AbstractEnum<?>,String>, AdapterObject>();