Package io.github.torand.javacommons.collection

Class CollectionHelper

java.lang.Object

io.github.torand.javacommons.collection.CollectionHelper

public final class CollectionHelper
extends Object

Helper functions for collections

Method Summary

Modifier and Type	Method	Description
static <T> List<T>	asList(Iterable<T> items)	Creates a list of specified iterable items.
static <T> List<T>	asList(T... items)	Creates a list of specified item array.
static <T> List<T>	asNonEmptyList(T first, T... others)	Creates a list of at least one, possibly multiple items.
static <T> List<T>	concat(Iterable<T> first, Iterable<T> second)	Concatenates the specified iterables into a single list.
static <T> List<T>	concat(Iterable<T> first, T... second)	Concatenates the elements of the specified iterable and array into a single list.
static <T> boolean	containsAny(Iterable<T> iterable, Predicate<T> predicate)	Tests whether the specified iterable contains an element satisfying a predicate.
static <T> boolean	containsOneOf(Iterable<T> iterable, T... items)	Tests whether the specified iterable contains one of the specified items.
static <T> T	headOf(Iterable<T> iterable)	Returns the first element of the specified iterable.
static boolean	isEmpty(Collection<?> collection)	Returns whether the specified collection is null or contains no elements.
static boolean	isEmpty(Map<?,?> map)	Returns whether the specified map is null or contains no elements.
static boolean	nonEmpty(Collection<?> collection)	Returns whether the specified collection contains at least one element.
static boolean	nonEmpty(Map<?,?> map)	Returns whether the specified map contains at least one element.
static <T> List<T>	reverse(Collection<T> collection)	Returns a new list with elements of specified collection in reversed order.
static <T> T	tailOf(Iterable<T> iterable)	Returns the last element of the specified iterable.

Methods inherited from class java.lang.Object

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

Method Details

asList

public static <T> List<T> asList(Iterable<T> items)

Creates a list of specified iterable items.

Type Parameters:

T - the item type.

Parameters:

items - the item iterable.

Returns:

the list.

asList

@SafeVarargs
public static <T> List<T> asList(T... items)

Creates a list of specified item array.

Type Parameters:

T - the item type.

Parameters:

items - the item array.

Returns:

the list.

asNonEmptyList

@SafeVarargs
public static <T> List<T> asNonEmptyList(T first,
 T... others)

Creates a list of at least one, possibly multiple items.

Type Parameters:

T - the item type.

Parameters:

first - the first item, which cannot be null.

others - the additional items, which can be null or empty.

Returns:

the list.

isEmpty

public static boolean isEmpty(Collection<?> collection)

Returns whether the specified collection is null or contains no elements.

Parameters:

collection - the collection.

Returns:

true if the collection is null or contains no elements; else false.

isEmpty

public static boolean isEmpty(Map<?,?> map)

Returns whether the specified map is null or contains no elements.

Parameters:

map - the map.

Returns:

true if the map is null or contains no elements; else false.

nonEmpty

public static boolean nonEmpty(Collection<?> collection)

Returns whether the specified collection contains at least one element.

Parameters:

collection - the collection.

Returns:

true if the collection contains at least one element; else false.

nonEmpty

public static boolean nonEmpty(Map<?,?> map)

Returns whether the specified map contains at least one element.

Parameters:

map - the map.

Returns:

true if the map contains at least one element; else false.

concat

public static <T> List<T> concat(Iterable<T> first,
 Iterable<T> second)

Concatenates the specified iterables into a single list.

Type Parameters:

T - the element type.

Parameters:

first - the first iterable.

second - the second iterable.

Returns:

the list.

concat

@SafeVarargs
public static <T> List<T> concat(Iterable<T> first,
 T... second)

Concatenates the elements of the specified iterable and array into a single list.

Type Parameters:

T - the element type.

Parameters:

first - the iterable.

second - the array.

Returns:

the list.

headOf

public static <T> T headOf(Iterable<T> iterable)

Returns the first element of the specified iterable.

Type Parameters:

T - the element type.

Parameters:

iterable - the iterable.

Returns:

the first element of the iterable.

tailOf

public static <T> T tailOf(Iterable<T> iterable)

Returns the last element of the specified iterable.

Type Parameters:

T - the element type.

Parameters:

iterable - the iterable.

Returns:

the lastelement of the iterable.

containsAny

public static <T> boolean containsAny(Iterable<T> iterable,
 Predicate<T> predicate)

Tests whether the specified iterable contains an element satisfying a predicate.

Type Parameters:

T - the element type.

Parameters:

iterable - the iterable.

predicate - the predicate.

Returns:

true if the iterable contains an element satisfying the predicate; else false.

containsOneOf

public static <T> boolean containsOneOf(Iterable<T> iterable,
 T... items)

Tests whether the specified iterable contains one of the specified items.

Type Parameters:

T - the element type.

Parameters:

iterable - the iterable.

items - the items to look for.

Returns:

true if the iterable contains one of the specified items; else false.

reverse

public static <T> List<T> reverse(Collection<T> collection)

Returns a new list with elements of specified collection in reversed order.

Type Parameters:

T - the element type.

Parameters:

collection - the collection

Returns:

the reversed list.