public final class Permissions extends PermissionCollection implements Serializable

This class represents a heterogeneous collection of permissions. That is, it contains different types of Permission objects, organized into PermissionCollection objects. For example, if any java.io.FilePermission objects are added to an instance of this class, they are all stored in a single PermissionCollection. It is the PermissionCollection returned by a call to the newPermissionCollection method in the FilePermission class. Similarly, any java.lang.RuntimePermission objects are stored in the PermissionCollection returned by a call to the newPermissionCollection method in the RuntimePermission class. Thus, this class represents a collection of PermissionCollection objects.

When the add method is called to add a Permission, the Permission is stored in the appropriate PermissionCollection. If no such collection exists yet, the Permission object's class is determined and the newPermissionCollection method is called on that class to create the PermissionCollection and add it to the Permissions object. If newPermissionCollection returns null, then a default PermissionCollection that uses a hashtable will be created and used. Each hashtable entry stores a Permission object as both the key and the value.

Enumerations returned via the elements method are not fail-fast. Modifications to a collection should not be performed while enumerating over that collection.