Package org.hibernate.internal.util.collections

Class CollectionHelper

java.lang.Object
org.hibernate.internal.util.collections.CollectionHelper
public final class CollectionHelper extends Object
Various helper util methods for handling collections.

  • Field Details

  • Method Details

    • mapOfSize

      public static <K, V> HashMap<K,V> mapOfSize(int size)
      Build a properly sized map, especially handling load size and load factor to prevent immediate resizing.

      Especially helpful for copy map contents.

      Parameters:
      size - The size to make the map.
      Returns:
      The sized map.

    • linkedMapOfSize

      public static <K, V> LinkedHashMap<K,V> linkedMapOfSize(int size)
      Build a properly sized linked map, especially handling load size and load factor to prevent immediate resizing.

      Especially helpful for copy map contents.

      Parameters:
      size - The size to make the map.
      Returns:
      The sized linked map.

    • map

      public static <K, V> HashMap<K,V> map()
      Build a map whose size is unknown.
      Returns:
      The map.

    • linkedMap

      public static <K, V> LinkedHashMap<K,V> linkedMap()
      Build a linked map whose size is unknown.
      Returns:
      The linked map.

    • setOfSize

      public static <K> HashSet<K> setOfSize(int size)
      Build a properly sized set, especially handling load size and load factor to prevent immediate resizing.

      Especially helpful for copy set contents.

      Parameters:
      size - The size to make the set.
      Returns:
      The sized set.

    • set

      public static <K> HashSet<K> set()
      Build a set whose size is unknown.
      Returns:
      The set.

    • linkedSetOfSize

      public static <K> LinkedHashSet<K> linkedSetOfSize(int size)
      Build a properly sized linked set, especially handling load size and load factor to prevent immediate resizing.

      Especially helpful for copy set contents.

      Parameters:
      size - The size to make the set.
      Returns:
      The sized linked set.

    • linkedSet

      public static <K> LinkedHashSet<K> linkedSet()
      Build a linked set whose size is unknown.
      Returns:
      The linked set.

    • determineProperSizing

      public static int determineProperSizing(Map<?,?> original)
      Given a map, determine the proper initial size for a new Map to hold the same number of values. Specifically we want to account for load size and load factor to prevent immediate resizing.
      Parameters:
      original - The original map
      Returns:
      The proper size.

    • makeCopy

      public static <X, Y> Map<X,Y> makeCopy(Map<X,Y> map)

    • makeCopy

      public static <K, V> HashMap<K,V> makeCopy(Map<K,V> original, Function<K,K> keyTransformer, Function<V,V> valueTransformer)

    • makeMap

      public static <K, V> Map<K,V> makeMap(Collection<V> collection, Function<V,K> keyProducer)

    • makeMap

      public static <K, V, E> Map<K,V> makeMap(Collection<E> collection, Function<E,K> keyProducer, Function<E,V> valueProducer)

    • determineProperSizing

      public static int determineProperSizing(Set<?> original)
      Given a set, determine the proper initial size for a new set to hold the same number of values. Specifically we want to account for load size and load factor to prevent immediate resizing.
      Parameters:
      original - The original set
      Returns:
      The proper size.

    • determineProperSizing

      public static int determineProperSizing(int numberOfElements)
      Determine the proper initial size for a new collection in order for it to hold the given a number of elements. Specifically we want to account for load size and load factor to prevent immediate resizing.
      Parameters:
      numberOfElements - The number of elements to be stored.
      Returns:
      The proper size.

    • concurrentMap

      public static <K, V> ConcurrentHashMap<K,V> concurrentMap(int expectedNumberOfElements)
      Create a properly sized ConcurrentHashMap based on the given expected number of elements.
      Type Parameters:
      K - The map key type
      V - The map value type
      Parameters:
      expectedNumberOfElements - The expected number of elements for the created map
      Returns:
      The created map.

    • concurrentMap

      public static <K, V> ConcurrentHashMap<K,V> concurrentMap(int expectedNumberOfElements, float loadFactor)
      Create a properly sized ConcurrentHashMap based on the given expected number of elements and an explicit load factor
      Type Parameters:
      K - The map key type
      V - The map value type
      Parameters:
      expectedNumberOfElements - The expected number of elements for the created map
      loadFactor - The collection load factor
      Returns:
      The created map.

    • arrayList

      public static <T> ArrayList<T> arrayList(int expectedNumberOfElements)

    • populatedArrayList

      public static <T> ArrayList<T> populatedArrayList(int expectedNumberOfElements, T value)

    • makeCopy

      public static <T> Set<T> makeCopy(Set<T> source)

    • isEmpty

      public static boolean isEmpty(Collection<?> collection)

    • isEmpty

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

    • isNotEmpty

      public static boolean isNotEmpty(Collection<?> collection)

    • isNotEmpty

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

    • isEmpty

      public static boolean isEmpty(Object[] objects)

    • isNotEmpty

      public static boolean isNotEmpty(Object[] objects)

    • listOf

      public static <T> List<T> listOf(T value1)

    • listOf

      public static <T> List<T> listOf(T... values)

    • setOf

      public static <T> Set<T> setOf(T... values)

    • setOf

      public static <T> Set<T> setOf(Collection<T> values)

    • asProperties

      public static Properties asProperties(Map<?,?> map)

    • toSmallSet

      public static <T> Set<T> toSmallSet(Set<T> set)
      Use to convert sets which will be retained for a long time, such as for the lifetime of the Hibernate ORM instance. The returned Set might be immutable, but there is no guarantee of this: consider it immutable but don't rely on this. The goal is to save memory.
      Returns:
      will never return null, but might return an immutable collection.

    • toSmallMap

      public static <K, V> Map<K,V> toSmallMap(Map<K,V> map)
      Use to convert Maps which will be retained for a long time, such as for the lifetime of the Hibernate ORM instance. The returned Map might be immutable, but there is no guarantee of this: consider it immutable but don't rely on this. The goal is to save memory.

    • toSmallList

      public static <V> List<V> toSmallList(ArrayList<V> arrayList)
      Use to convert ArrayList instances which will be retained for a long time, such as for the lifetime of the Hibernate ORM instance. The returned List might be immutable, but there is no guarantee of this: consider it immutable but don't rely on this. The goal is to save memory.

    • combine

      public static <O> List<O> combine(List<O> list1, List<O> list2)

    • combineUntyped

      public static List combineUntyped(List list1, List list2)

    • combine

      @SafeVarargs public static <O> List<O> combine(List<O>... lists)

    • size

      public static int size(List<?> values)

    • size

      public static int size(Collection<?> values)

    • size

      public static int size(Map<?,?> values)

    • toSet

      @SafeVarargs public static <X> Set<X> toSet(X... values)

    • mutableJoin

      public static <E> List<E> mutableJoin(Collection<E> first, Collection<E> second)

    • mutableJoin

      @SafeVarargs public static <E> List<E> mutableJoin(Collection<E> first, Collection<E>... others)