jsimple.util

Class ListUtils

java.lang.Object

jsimple.util.ListUtils

public class ListUtils
extends java.lang.Object

Created by Bret on 5/19/2014.

Constructor Summary

Constructors

Constructor and Description
ListUtils()

Method Summary

Modifier and Type	Method and Description
static int	arrayListHashCode(ArrayList<?> list) Get the "deep" hash code for an ArrayList, by combining hash codes of elements in the list.
static boolean	arrayListsEqual(ArrayList<?> list1, ArrayList<?> list2) See if two ArrayLists are the same.
static <E> ArrayList<E>	distinctElements(List<E> list) Return a list of all distinct elements in the list, removing any duplicates.

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

arrayListsEqual

public static boolean arrayListsEqual(ArrayList<?> list1,
                                      ArrayList<?> list2)

See if two ArrayLists are the same. They are considered the same if their elements are all equal, according to the "equals" method. This method can be used to overcome an incompatibility between Java and C# in the equals method for lists; Java checks for "deep" equality (like this method) while C# normally just checks if the lists reference the same object. Using this method instead provides deep equality semantics for both.

Parameters:

list1 - 1st ArrayList

list2 - 2nd ArrayList

Returns:

true if the lists are equal, checking member by member equality, and false if not

arrayListHashCode

public static int arrayListHashCode(ArrayList<?> list)

Get the "deep" hash code for an ArrayList, by combining hash codes of elements in the list. This method can be used to overcome an incompatibility between Java and C# in the hashCode method for lists; Java checks for "deep" hash code (like this method) while C# normally just checks computes hash code based on object identity. Using this method instead provides deep hash code semantics for both. If you use this, you'll also want to use arrayListsEqual for equality, as the semantics of equality / hashCode have to go together (rule being if two objects equal, they MUST have the same hash code, which is true for both Java & C#).

Parameters:

list - list to compute hashCode of

Returns:

list hash code, based on list elements

distinctElements

public static <E> ArrayList<E> distinctElements(List<E> list)

Return a list of all distinct elements in the list, removing any duplicates. Returned items are in the same order as in the original list. Note that the input list shouldn't contain any nulls--results are undefined if it does.

Type Parameters:

E - list element type

Parameters:

list - list to remove duplicates from

Returns:

list with duplicates removed