graphql.collect

Class ImmutableKit

java.lang.Object

graphql.collect.ImmutableKit

public final class ImmutableKit
extends java.lang.Object

Constructor Summary

Constructors

Constructor and Description
ImmutableKit()

Method Summary

Modifier and Type	Method and Description
static <T> com.google.common.collect.ImmutableList<T>	addToList(java.util.Collection<? extends T> existing, T newValue, T... extraValues) This constructs a new Immutable list from an existing collection and adds a new element to it.
static <K,V> com.google.common.collect.ImmutableMap<K,V>	addToMap(java.util.Map<K,V> existing, K newKey, V newVal)
static <T> com.google.common.collect.ImmutableList<T>	concatLists(java.util.List<T> l1, java.util.List<T> l2)
static <T> com.google.common.collect.ImmutableList<T>	emptyList()
static <K,V> com.google.common.collect.ImmutableMap<K,V>	emptyMap()
static <T,R> com.google.common.collect.ImmutableList<R>	map(java.lang.Iterable<? extends T> iterable, java.util.function.Function<? super T,? extends R> mapper) This is more efficient than `c.stream().map().collect()` because it does not create the intermediate objects needed for the flexible style.
static <K,V> com.google.common.collect.ImmutableMap<K,V>	mergeMaps(java.util.Map<K,V> m1, java.util.Map<K,V> m2)
static <T> com.google.common.collect.ImmutableList<T>	nonNullCopyOf(java.util.Collection<T> collection)
static <K,V> com.google.common.collect.ImmutableMap<K,com.google.common.collect.ImmutableList<V>>	toImmutableMapOfLists(java.util.Map<K,java.util.List<V>> startingMap) ImmutableMaps are hard to build via Map.computeIfAbsent(Object, Function) style.

Methods inherited from class java.lang.Object

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

Constructor Detail

ImmutableKit

public ImmutableKit()

Method Detail

emptyList

public static <T> com.google.common.collect.ImmutableList<T> emptyList()

nonNullCopyOf

public static <T> com.google.common.collect.ImmutableList<T> nonNullCopyOf(java.util.Collection<T> collection)

emptyMap

public static <K,V> com.google.common.collect.ImmutableMap<K,V> emptyMap()

toImmutableMapOfLists

public static <K,V> com.google.common.collect.ImmutableMap<K,com.google.common.collect.ImmutableList<V>> toImmutableMapOfLists(java.util.Map<K,java.util.List<V>> startingMap)

ImmutableMaps are hard to build via Map.computeIfAbsent(Object, Function) style. This methods allows you to take a mutable map with mutable list of keys and make it immutable.

This of course has a cost - if the map is very large you will be using more memory. But for static maps that live a long life it maybe be worth it.

Type Parameters:

K - for key

V - for victory

Parameters:

startingMap - the starting input map

Returns:

and Immutable map of ImmutableList values

addToMap

public static <K,V> com.google.common.collect.ImmutableMap<K,V> addToMap(java.util.Map<K,V> existing,
                                                                         K newKey,
                                                                         V newVal)

mergeMaps

public static <K,V> com.google.common.collect.ImmutableMap<K,V> mergeMaps(java.util.Map<K,V> m1,
                                                                          java.util.Map<K,V> m2)

concatLists

public static <T> com.google.common.collect.ImmutableList<T> concatLists(java.util.List<T> l1,
                                                                         java.util.List<T> l2)

map

public static <T,R> com.google.common.collect.ImmutableList<R> map(java.lang.Iterable<? extends T> iterable,
                                                                   java.util.function.Function<? super T,? extends R> mapper)

This is more efficient than `c.stream().map().collect()` because it does not create the intermediate objects needed for the flexible style. Benchmarking has shown this to outperform `stream()`.

Type Parameters:

T - for two

R - for result

Parameters:

iterable - the iterable to map

mapper - the mapper function

Returns:

a map immutable list of results

addToList

public static <T> com.google.common.collect.ImmutableList<T> addToList(java.util.Collection<? extends T> existing,
                                                                       T newValue,
                                                                       T... extraValues)

This constructs a new Immutable list from an existing collection and adds a new element to it.

Type Parameters:

T - for two

Parameters:

existing - the existing collection

newValue - the new value to add

extraValues - more values to add

Returns:

an Immutable list with the extra effort.