Package io.helidon.common

Class CollectionsHelper

java.lang.Object

io.helidon.common.CollectionsHelper

public abstract class CollectionsHelper
extends java.lang.Object

A set of static methods similar to Java9's List.of(), Set.of() and Map.of().

Method Summary

Modifier and Type	Method	Description
static <T> java.util.List<T>	listOf()	Returns an immutable list containing zero elements.
static <T> java.util.List<T>	listOf(T... elts)	Returns an unmodifiable list containing the given elements.
static <K,V> java.util.Map.Entry<K,V>	mapEntry(K k, V v)	Returns an Map.Entry containing the given key and value.
static <K,V> java.util.Map<K,V>	mapOf()	Returns an immutable map containing zero mappings.
static <K,V> java.util.Map<K,V>	mapOf(K k1, V v1)	Create an unmodifiable map containing a single mappings.
static <K,V> java.util.Map<K,V>	mapOf(K k1, V v1, K k2, V v2)	Create an unmodifiable map containing 2 mappings.
static <K,V> java.util.Map<K,V>	mapOf(K k1, V v1, K k2, V v2, K k3, V v3)	Create an unmodifiable map containing 3 mappings.
static <K,V> java.util.Map<K,V>	mapOf(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4)	Create an unmodifiable map containing 4 mappings.
static <K,V> java.util.Map<K,V>	mapOf(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5)	Create an unmodifiable map containing 5 mappings.
static <K,V> java.util.Map<K,V>	mapOf(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6)	Create an unmodifiable map containing 5 mappings.
static <K,V> java.util.Map<K,V>	mapOf(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7)	Create an unmodifiable map containing 5 mappings.
static <T> java.util.Set<T>	setOf()	Returns an immutable set containing zero elements.
static <T> java.util.Set<T>	setOf(T... elts)	Create an unmodifiable set containing the given elements.

Methods inherited from class java.lang.Object

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

Method Detail

listOf

public static <T> java.util.List<T> listOf()

Returns an immutable list containing zero elements.

Type Parameters:

T - the List's element type

Returns:

an empty List

listOf

@SafeVarargs
public static <T> java.util.List<T> listOf(T... elts)

Returns an unmodifiable list containing the given elements.

Type Parameters:

T - the List's element type

Parameters:

elts - the elements

Returns:

a List containing the specified elements

setOf

public static <T> java.util.Set<T> setOf()

Returns an immutable set containing zero elements.

Type Parameters:

T - the Set's element type

Returns:

an empty Set

setOf

@SafeVarargs
public static <T> java.util.Set<T> setOf(T... elts)

Create an unmodifiable set containing the given elements.

Type Parameters:

T - the Set's element type

Parameters:

elts - elements to add

Returns:

a Set containing the specified elements

mapEntry

public static <K,V> java.util.Map.Entry<K,V> mapEntry(K k,
                                                      V v)

Returns an Map.Entry containing the given key and value.

Type Parameters:

K - the key's type

V - the value's type

Parameters:

k - key

v - value

Returns:

an Entry containing the specified key and value

mapOf

public static <K,V> java.util.Map<K,V> mapOf()

Returns an immutable map containing zero mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Returns:

an empty Map

mapOf

public static <K,V> java.util.Map<K,V> mapOf(K k1,
                                             V v1)

Create an unmodifiable map containing a single mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Parameters:

k1 - key

v1 - value

Returns:

a Map containing the specified mappings

mapOf

public static <K,V> java.util.Map<K,V> mapOf(K k1,
                                             V v1,
                                             K k2,
                                             V v2)

Create an unmodifiable map containing 2 mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Parameters:

k1 - first key

v1 - first value

k2 - second key

v2 - second value

Returns:

a Map containing the specified mappings

mapOf

public static <K,V> java.util.Map<K,V> mapOf(K k1,
                                             V v1,
                                             K k2,
                                             V v2,
                                             K k3,
                                             V v3)

Create an unmodifiable map containing 3 mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Parameters:

k1 - first key

v1 - first value

k2 - second key

v2 - second value

k3 - third key

v3 - third value

Returns:

a Map containing the specified mappings

mapOf

public static <K,V> java.util.Map<K,V> mapOf(K k1,
                                             V v1,
                                             K k2,
                                             V v2,
                                             K k3,
                                             V v3,
                                             K k4,
                                             V v4)

Create an unmodifiable map containing 4 mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Parameters:

k1 - first key

v1 - first value

k2 - second key

v2 - second value

k3 - third key

v3 - third value

k4 - fourth key

v4 - fourth value

Returns:

a Map containing the specified mappings

mapOf

public static <K,V> java.util.Map<K,V> mapOf(K k1,
                                             V v1,
                                             K k2,
                                             V v2,
                                             K k3,
                                             V v3,
                                             K k4,
                                             V v4,
                                             K k5,
                                             V v5)

Create an unmodifiable map containing 5 mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Parameters:

k1 - first key

v1 - first value

k2 - second key

v2 - second value

k3 - third key

v3 - third value

k4 - fourth key

v4 - fourth value

k5 - fifth key

v5 - fifth value

Returns:

a Map containing the specified mappings

mapOf

public static <K,V> java.util.Map<K,V> mapOf(K k1,
                                             V v1,
                                             K k2,
                                             V v2,
                                             K k3,
                                             V v3,
                                             K k4,
                                             V v4,
                                             K k5,
                                             V v5,
                                             K k6,
                                             V v6)

Create an unmodifiable map containing 5 mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Parameters:

k1 - first key

v1 - first value

k2 - second key

v2 - second value

k3 - third key

v3 - third value

k4 - fourth key

v4 - fourth value

k5 - fifth key

v5 - fifth value

k6 - sixth key

v6 - sixth value

Returns:

a Map containing the specified mappings

mapOf

public static <K,V> java.util.Map<K,V> mapOf(K k1,
                                             V v1,
                                             K k2,
                                             V v2,
                                             K k3,
                                             V v3,
                                             K k4,
                                             V v4,
                                             K k5,
                                             V v5,
                                             K k6,
                                             V v6,
                                             K k7,
                                             V v7)

Create an unmodifiable map containing 5 mappings.

Type Parameters:

K - the Map's key type

V - the Map's value type

Parameters:

k1 - first key

v1 - first value

k2 - second key

v2 - second value

k3 - third key

v3 - third value

k4 - fourth key

v4 - fourth value

k5 - fifth key

v5 - fifth value

k6 - sixth key

v6 - sixth value

k7 - seventh key

v7 - seventh value

Returns:

a Map containing the specified mappings