freenet.support

Class ListUtils

java.lang.Object

freenet.support.ListUtils

public class ListUtils
extends java.lang.Object

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ListUtils.RandomRemoveResult<E>

Constructor Summary

Constructors

Constructor and Description
ListUtils()

Method Summary

Modifier and Type	Method and Description
static <E> E	removeBySwapLast(java.util.List<E> a, int idx) Removes element by index from List by swapping with last element.
static <E> boolean	removeBySwapLast(java.util.List<E> a, java.lang.Object o) Removes element from List by swapping with last element.
static <E> ListUtils.RandomRemoveResult<E>	removeRandomBySwapLast(java.util.Random random, java.util.List<E> a) Removes random element from List by swapping with last element.
static <E> E	removeRandomBySwapLastSimple(java.util.Random random, java.util.List<E> a) Removes random element from List by swapping with last element.

Methods inherited from class java.lang.Object

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

Constructor Detail

ListUtils

public ListUtils()

Method Detail

removeBySwapLast

public static <E> boolean removeBySwapLast(java.util.List<E> a,
                                           java.lang.Object o)

Removes element from List by swapping with last element. O(n) comparison, O(1) moves. This method is useful with ArrayList-alike containers with O(1) get(index) and O(n) remove(index) when keeping array order is not important. Not synchronized (even with synchronized containers).

Returns:

true if element was removed.

removeBySwapLast

public static <E> E removeBySwapLast(java.util.List<E> a,
                                     int idx)

Removes element by index from List by swapping with last element. 0 comparison, O(1) moves. This method is useful with ArrayList-alike containers with O(1) get(index) and O(n) remove(index) when keeping array order is not important. Not synchronized (even with synchronized containers!).

Returns:

moved element that will replace current index or removed element if it was last element (and nothing was moved). WARNING: returned result is DIFFERENT from List.remove(index)! (this is intentional to allow useful optimizations).

Throws:

java.lang.IndexOutOfBoundsException - if idx is not valid index WARNING: Don't dare to break this method contract!

removeRandomBySwapLast

public static <E> ListUtils.RandomRemoveResult<E> removeRandomBySwapLast(java.util.Random random,
                                                                         java.util.List<E> a)

Removes random element from List by swapping with last element. O(1) moves. This method is useful with ArrayList-alike containers with O(1) get(index) and O(n) remove(index) when keeping array order is not important. Not synchronized (even with synchronized containers!). WARNING: amount of fetched random data is implementation-defined

Returns:

null if list is empty, otherwise RandomRemoveResult(removed_element, moved_element)

removeRandomBySwapLastSimple

public static <E> E removeRandomBySwapLastSimple(java.util.Random random,
                                                 java.util.List<E> a)

Removes random element from List by swapping with last element. O(1) moves. This method is useful with ArrayList-alike containers with O(1) get(index) and O(n) remove(index) when keeping array order is not important. Not synchronized (even with synchronized containers!). WARNING: amount of fetched random data is implementation-defined

Returns:

null if list is empty, removed element otherwise