i3.dragos.util
Class CollectionHelper

java.lang.Object
  i3.dragos.util.CollectionHelper

public final class CollectionHelper
extends java.lang.Object

Helper class for retrieving a single element from a collection while ensuring in the process that the collection contains exactly one item.

Author:

Thorsten Hermes <thermes@i3.informatik.rwth-aachen.de>

Method Summary

static <T> T	getSingleElement(java.util.Collection<T> c) Returns a single element from a Collection, does not specify the caller.
static <T> T	getSingleElement(java.util.Collection<T> c, java.lang.String caller) Returns a single element from a Collection.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getSingleElement

public static <T> T getSingleElement(java.util.Collection<T> c)
                          throws EntityNotFoundException,
                                 MultipleResultsException

Returns a single element from a Collection, does not specify the caller.

Type Parameters:

T - The type of the elements in the collection.

Parameters:

c - The Collection.

Returns:

the single element.

Throws:

EntityNotFoundException - if the Collection is emtpy.

MultipleResultsException - if the Collection contained more than one element.

getSingleElement

public static <T> T getSingleElement(java.util.Collection<T> c,
                                     java.lang.String caller)
                          throws EntityNotFoundException,
                                 MultipleResultsException

Returns a single element from a Collection.

Type Parameters:

T - The type of the elements in the collection.

Parameters:

c - The Collection.

caller - Name of calling method, used in error messages (may be null).

Returns:

the single element.

Throws:

EntityNotFoundException - if the Collection is emtpy.

MultipleResultsException - if the Collection contained more than one element.