Package org.ethelred.util.collect

Class Sequences

java.lang.Object

org.ethelred.util.collect.Sequences

public class Sequences
extends Object

Utility functions for Lists.

Method Summary

Modifier and Type	Method	Description
static <T,C extends Collection<T>> C	concat(Collection<? extends T> a, Collection<? extends T> b, IntFunction<C> collectionSupplier)	Join two Collections into one.
static <T> List<T>	concat(List<? extends T> a, List<? extends T> b)	Join two Lists into one.
static <T> List<T>	concat(List<? extends T> list, T... items)	Join some items to the end of a List.
static <T> List<T>	head(List<T> list, int items)	Retrieve items from the start of a List.
static <T> List<List<T>>	prefixes(Iterable<T> iterable)	Get all possible prefixes of an Iterable.
static <T> List<T>	tail(List<T> list, int items)	Like head, except it works backwards from the end of the list.

Methods inherited from class java.lang.Object

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

Method Detail

prefixes

public static <T> List<List<T>> prefixes(Iterable<T> iterable)

Get all possible prefixes of an Iterable. For example, if the parameter is a list [1,2,3], the result will be [[],[1],[1,2],[1,2,3]].

Type Parameters:

T - the type of elements

Parameters:

iterable - The starting value

Returns:

A list of lists

concat

public static <T,C extends Collection<T>> C concat(Collection<? extends T> a,
                                                         Collection<? extends T> b,
                                                         IntFunction<C> collectionSupplier)

Join two Collections into one.

Type Parameters:

T - the type of elements

C - the type of Collection to return

Parameters:

a - first collection

b - second collection

collectionSupplier - Function to construct the collection to return. The int parameter is the expected size of the resulting collection.

Returns:

the combined collection

concat

public static <T> List<T> concat(List<? extends T> a,
                                 List<? extends T> b)

Join two Lists into one. The order will be all elements of a followed by all elements of b.

Type Parameters:

T - the type of elements

Parameters:

a - first list

b - second list

Returns:

Combined list

concat

@SafeVarargs
public static <T> List<T> concat(List<? extends T> list,
                                 T... items)

Join some items to the end of a List.

Type Parameters:

T - the type of elements

Parameters:

list - original list

items - items to add to the list

Returns:

Combined list

head

public static <T> List<T> head(List<T> list,
                               int items)

Retrieve items from the start of a List.

Type Parameters:

T - the type of elements

Parameters:

list - list to draw from

items - When positive, return that many items from the start. When negative, return items from the start of the list except for that number at the end. When 0, return an empty list, though I'm not sure why you would want to do that. If greater than the size of the list, the original list is returned.

Returns:

resulting list

tail

public static <T> List<T> tail(List<T> list,
                               int items)

Like head, except it works backwards from the end of the list.