co.codewizards.cloudstore.core.collection

Class ListMerger<E,K>

java.lang.Object

co.codewizards.cloudstore.core.collection.ListMerger<E,K>

Type Parameters:

E - the element type.

K - the key type (either the same as the element or a key contained in each list element).

public abstract class ListMerger<E,K>
extends Object

Helper merging a given source-List into a given destination-List.

Author:

Marco หงุ่ยตระกูล-Schulze - marco at codewizards dot co

Constructor Summary

Constructors

Constructor and Description
ListMerger()

Method Summary

Modifier and Type	Method and Description
protected void	add(List<E> dest, int index, E element) Add the given element to the given destination-List dest at the specified index.
protected abstract K	getKey(E element) Get the key from the given element.
void	merge(List<E> source, List<E> dest) Merge the given source into the given destination.
protected void	populateDestKey2element()
protected void	populateSourceKey2element()
protected abstract void	update(List<E> dest, int index, E sourceElement, E destElement) Update the the given destElement with the data from sourceElement; or replace it altogether.

Methods inherited from class java.lang.Object

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

Constructor Detail

ListMerger

public ListMerger()

Method Detail

merge

public void merge(List<E> source,
                  List<E> dest)

Merge the given source into the given destination.

After this operation, both lists are semantically equal. This does not mean that their equals(...) method returns true, though! This is, because the lists are merged based on a key which might be wrapped by the elements. The elements are not required to correctly implement equals(...).

Parameters:

source - the source from which to copy. Must not be null.

dest - the destination into which to write. Must not be null.

add

protected void add(List<E> dest,
                   int index,
                   E element)

Add the given element to the given destination-List dest at the specified index.

The default implementation simply calls: dest.add(index, element);

Parameters:

dest - the destination. Never null.

index - the index at which the new element should be added.

element - the element to be added.

getKey

protected abstract K getKey(E element)

Get the key from the given element.

If the element is the same as the key, this method should return the given element.

Parameters:

element - the element from which to extract the key. May be null, if the source or the destination List contains null elements.

Returns:

the key. May be null.

update

protected abstract void update(List<E> dest,
                               int index,
                               E sourceElement,
                               E destElement)

Update the the given destElement with the data from sourceElement; or replace it altogether.

Depending on whether the elements wrap the actual information in a mutable way, or whether they are immutable, this method may either copy the data from the sourceElement into the destElement or instead invoke dest.set(index, sourceElement).

Important: This method is only invoked, if the key of both sourceElement and destElement is the same!

Parameters:

dest - the destination List. Never null.

index - the index in dest addressing the element to be replaced.

sourceElement - the source from which to copy. May be null, if the source contains null elements.

destElement - the destination into which to write. May be null, if the destination contains null elements.

populateSourceKey2element

protected void populateSourceKey2element()

populateDestKey2element

protected void populateDestKey2element()