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* accompanied this code).
*
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package java.security.acl;
import java.util.Enumeration;
import java.security.Principal;
/**
* This interface is used to represent a group of principals. (A principal
* represents an entity such as an individual user or a company). <p>
*
* Note that Group extends Principal. Thus, either a Principal or a Group can
* be passed as an argument to methods containing a Principal parameter. For
* example, you can add either a Principal or a Group to a Group object by
* calling the object's <code>addMember</code> method, passing it the
* Principal or Group.
*
* @author Satish Dharmaraj
*/
public interface Group extends Principal {
/**
* Adds the specified member to the group.
*
* @param user the principal to add to this group.
*
* @return true if the member was successfully added,
* false if the principal was already a member.
*/
public boolean addMember(Principal user);
/**
* Removes the specified member from the group.
*
* @param user the principal to remove from this group.
*
* @return true if the principal was removed, or
* false if the principal was not a member.
*/
public boolean removeMember(Principal user);
/**
* Returns true if the passed principal is a member of the group.
* This method does a recursive search, so if a principal belongs to a
* group which is a member of this group, true is returned.
*
* @param member the principal whose membership is to be checked.
*
* @return true if the principal is a member of this group,
* false otherwise.
*/
public boolean isMember(Principal member);
/**
* Returns an enumeration of the members in the group.
* The returned objects can be instances of either Principal
* or Group (which is a subclass of Principal).
*
* @return an enumeration of the group members.
*/
public Enumeration<? extends Principal> members();
}