org.incava.ijdk.util

Class ListExt

java.lang.Object

org.incava.ijdk.lang.ObjectExt

org.incava.ijdk.util.CollectionExt

org.incava.ijdk.util.ListExt

public class ListExt
extends CollectionExt

Constructor Summary

Constructors

Constructor and Description
ListExt()

Method Summary

Modifier and Type	Method and Description
static <T> java.util.List<T>	create(T... elements) Returns a list (an ArrayList) initialized with the given elements.
static <T> T	first(java.util.List<T> list) Returns the first element in the list.
static <T> T	get(java.util.List<T> list, int index) Returns the nth element in the list, where n can be negative, to index from the end of the list.
static java.lang.Integer	getIndex(java.lang.Integer size, java.lang.Integer index) Converts the index, which can be positive or negative, to one within the given size, representing the length of a list.
static <Type> Type	getRandomElement(java.util.List<Type> list) Returns a random element from the list, or null if the list is null or empty.
static <T> T	last(java.util.List<T> list) Returns the last element in the list.
static <T> boolean	removeAll(java.util.List<T> list, T element) Removes all occurrances of element from list, returning whether any were found.

Methods inherited from class org.incava.ijdk.util.CollectionExt

any, contains, hasAll, hasAny, intersection, intersection

Methods inherited from class org.incava.ijdk.lang.ObjectExt

areEqual, compare, equal, isEmpty, isFalse, isNotNull, isNull, isTrue

Methods inherited from class java.lang.Object

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

Constructor Detail

ListExt

public ListExt()

Method Detail

first

public static <T> T first(java.util.List<T> list)

Returns the first element in the list.

last

public static <T> T last(java.util.List<T> list)

Returns the last element in the list.

get

public static <T> T get(java.util.List<T> list,
                        int index)

Returns the nth element in the list, where n can be negative, to index from the end of the list. Returns null if out of bounds.

getIndex

public static java.lang.Integer getIndex(java.lang.Integer size,
                                         java.lang.Integer index)

Converts the index, which can be positive or negative, to one within the given size, representing the length of a list. A negative index will result in the distance from the end of the list, with index -1 meaning the last element in the list. Returns null if the resulting index is out of range.

See Also:

Index.getIndex(java.lang.Integer, java.lang.Integer)

removeAll

public static <T> boolean removeAll(java.util.List<T> list,
                                    T element)

Removes all occurrances of element from list, returning whether any were found. Returns false if list is null.

getRandomElement

public static <Type> Type getRandomElement(java.util.List<Type> list)

Returns a random element from the list, or null if the list is null or empty.

create

@SafeVarargs
public static <T> java.util.List<T> create(T... elements)

Returns a list (an ArrayList) initialized with the given elements. The list returned is of dynamic size (unlike Arrays.asList(...), which returns a fixed-size array). The following two blocks are equivalent:

     List<String> names = new ArrayList<String>(Arrays.asList("kevin", "jacob", "isaac"));
     names.add("henry");
 

     List<String> names = list("kevin", "jacob", "isaac");
     names.add("henry");