org.opennms.core.utils

Class ImmutableCollections<T>

java.lang.Object

org.opennms.core.utils.ImmutableCollections<T>

Type Parameters:

T - the type the returned collection will hold

public class ImmutableCollections<T>
extends Object

Utility class for copying a collection ensuring copied elements are immutable.

This class is used to achieve deep immutability for value classes by ensuring collections in those classes contain immutable elements in addition to being immutable themselves.

Author:

mbrooks

Method Summary

Modifier and Type	Method and Description
List<T>	newList(Collection<T> toCopy) Create a new unmodifiable List containing immutable copies of the given elements.
static <T> List<T>	newListOfImmutableType(Collection<T> toCopy) Creates an unmodifiable copy of a Collection that already contains immutable types.
static <T,S> Map<T,S>	newMapOfImmutableTypes(Map<T,S> toCopy)
static <T,S> Map<T,S>	newMapOfImmutableTypes(Map<T,S> toCopy, java.util.function.Supplier<Map<T,S>> mapSupplier) Creates an unmodifiable copy of a Map that already contains immutable types.
static <T> ImmutableCollections<T>	with(java.util.function.Function<T,T> immutableInstanceFactory) Creates an instance that maps elements to an immutable form using the given mapping function.

Methods inherited from class java.lang.Object

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

Method Detail

with

public static <T> ImmutableCollections<T> with(java.util.function.Function<T,T> immutableInstanceFactory)

Creates an instance that maps elements to an immutable form using the given mapping function.

The mapping function may return the element unmapped if it is already considered immutable.

Parameters:

immutableInstanceFactory - a function for mapping an element to an immutable copy of that element

Returns:

a new instance with the given mapping function

newList

public List<T> newList(Collection<T> toCopy)

Create a new unmodifiable List containing immutable copies of the given elements.

Parameters:

toCopy - the Collection containing the elements to be copied

Returns:

a new unmodifiable List containing immutable copies of the given elements

newListOfImmutableType

public static <T> List<T> newListOfImmutableType(Collection<T> toCopy)

Creates an unmodifiable copy of a Collection that already contains immutable types. This is essentially a convenience method for avoiding NPE when using a List copy constructor.

Parameters:

toCopy - the Collection to copy

Returns:

an unmodifiable List containing the same elements as in the given Collection

newMapOfImmutableTypes

public static <T,S> Map<T,S> newMapOfImmutableTypes(Map<T,S> toCopy,
                                                    java.util.function.Supplier<Map<T,S>> mapSupplier)

Creates an unmodifiable copy of a Map that already contains immutable types. This is essentially a convenience method for avoiding NPE when using a Map copy constructor.

Parameters:

toCopy - the collection to copy

mapSupplier - a supplier that supplies the desired type of Map

Returns:

an unmodifiable Map containing the same elements as in the given Map

newMapOfImmutableTypes

public static <T,S> Map<T,S> newMapOfImmutableTypes(Map<T,S> toCopy)