Package com.okta.commons.lang

Class Collections

java.lang.Object
com.okta.commons.lang.Collections
public abstract class Collections extends Object

  • Constructor Summary

    Constructors
    Constructor
    Description
    Collections()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static List
    arrayToList(Object source)
    Convert the supplied array into a List.
    static boolean
    contains(Enumeration enumeration, Object element)
    Check whether the given Enumeration contains the given element.
    static boolean
    contains(Iterator iterator, Object element)
    Check whether the given Iterator contains the given element.
    static boolean
    containsAny(Collection source, Collection candidates)
    Return true if any element in 'candidates' is contained in 'source'; otherwise returns false.
    static boolean
    containsInstance(Collection collection, Object element)
    Check whether the given Collection contains the given element instance.
    static Class<?>
    findCommonElementType(Collection collection)
    Find the common element type of the given Collection, if any.
    static Object
    findFirstMatch(Collection source, Collection candidates)
    Return the first element in 'candidates' that is contained in 'source'.
    static <T> T
    findFirstValueOfType(Collection<?> collection, Class<T> type)
    Find the first single value of the given type in the given Collection or null if none was found
    static Object
    findValueOfType(Collection<?> collection, Class<?>[] types)
    Find a single value of one of the given types in the given Collection: searching the Collection for a value of the first type, then searching for a value of the second type, etc.
    static boolean
    hasUniqueObject(Collection collection)
    Determine whether the given Collection only contains a single unique object.
    static boolean
    isEmpty(Collection collection)
    Return true if the supplied Collection is null or empty.
    static boolean
    isEmpty(Map map)
    Return true if the supplied Map is null or empty.
    static void
    mergeArrayIntoCollection(Object array, Collection collection)
    Merge the given array into the given Collection.
    static void
    mergePropertiesIntoMap(Properties props, Map map)
    Merge the given Properties instance into the given Map, copying all properties (key-value pairs) over.
    static int
    size(Collection collection)
    Returns the collection's size or 0 if the collection is null.
    static int
    size(Map map)
    Returns the map's size or 0 if the map is null.
    static <T> T[]
    toArray(Collection<T> c, Class<T> type)
     
    static <A, E extends A>
    A[]
    toArray(Enumeration<E> enumeration, A[] array)
    Marshal the elements from the given enumeration into an array of the given type.
    static <E> Iterator<E>
    toIterator(Enumeration<E> enumeration)
    Adapt an enumeration to an iterator.
    static <T> List<T>
    toList(Collection<T> elements)
    a new List that contains the specified elements or an empty collection if the elements are null or empty.
    static <T> List<T>
    toList(T... elements)
    a new List that contains the specified elements or an empty collection if the elements are null or empty.
    static <E> Set<E>
    toSet(E... elements)
    Returns a new Set that contains the specified elements or an empty Set if the elements are null or empty.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Collections

      public Collections()

  • Method Details

    • isEmpty

      public static boolean isEmpty(Collection collection)
      Return true if the supplied Collection is null or empty. Otherwise, return false.
      Parameters:
      collection - the Collection to check
      Returns:
      whether the given Collection is empty

    • size

      public static int size(Collection collection)
      Returns the collection's size or 0 if the collection is null.
      Parameters:
      collection - the collection to check.
      Returns:
      the collection's size or 0 if the collection is null.

    • size

      public static int size(Map map)
      Returns the map's size or 0 if the map is null.
      Parameters:
      map - the map to check
      Returns:
      the map's size or 0 if the map is null.

    • isEmpty

      public static boolean isEmpty(Map map)
      Return true if the supplied Map is null or empty. Otherwise, return false.
      Parameters:
      map - the Map to check
      Returns:
      whether the given Map is empty

    • arrayToList

      public static List arrayToList(Object source)
      Convert the supplied array into a List. A primitive array gets converted into a List of the appropriate wrapper type.

      A null source value will be converted to an empty List.

      Parameters:
      source - the (potentially primitive) array
      Returns:
      the converted List result
      See Also:

    • toList

      public static <T> List<T> toList(T... elements)
      a new List that contains the specified elements or an empty collection if the elements are null or empty.
      Type Parameters:
      T - the type of elements in the collection
      Parameters:
      elements - the elements to put in the list.
      Returns:
      a new List that contains the specified elements or an empty collection if the elements are null or empty.

    • toList

      public static <T> List<T> toList(Collection<T> elements)
      a new List that contains the specified elements or an empty collection if the elements are null or empty.
      Type Parameters:
      T - the type of elements in the collection
      Parameters:
      elements - the elements to put in the list.
      Returns:
      a new List that contains the specified elements or an empty collection if the elements are null or empty.

    • toSet

      public static <E> Set<E> toSet(E... elements)
      Returns a new Set that contains the specified elements or an empty Set if the elements are null or empty.
      Type Parameters:
      E - the type of elements in the set
      Parameters:
      elements - elements to add to the new set
      Returns:
      a new Set that contains the specified elements or an empty Set if the elements are null or empty.

    • mergeArrayIntoCollection

      public static void mergeArrayIntoCollection(Object array, Collection collection)
      Merge the given array into the given Collection.
      Parameters:
      array - the array to merge (may be null)
      collection - the target Collection to merge the array into

    • mergePropertiesIntoMap

      public static void mergePropertiesIntoMap(Properties props, Map map)
      Merge the given Properties instance into the given Map, copying all properties (key-value pairs) over.

      Uses Properties.propertyNames() to even catch default properties linked into the original Properties instance.

      Parameters:
      props - the Properties instance to merge (may be null)
      map - the target Map to merge the properties into

    • contains

      public static boolean contains(Iterator iterator, Object element)
      Check whether the given Iterator contains the given element.
      Parameters:
      iterator - the Iterator to check
      element - the element to look for
      Returns:
      true if found, false else

    • contains

      public static boolean contains(Enumeration enumeration, Object element)
      Check whether the given Enumeration contains the given element.
      Parameters:
      enumeration - the Enumeration to check
      element - the element to look for
      Returns:
      true if found, false else

    • containsInstance

      public static boolean containsInstance(Collection collection, Object element)
      Check whether the given Collection contains the given element instance.

      Enforces the given instance to be present, rather than returning true for an equal element as well.

      Parameters:
      collection - the Collection to check
      element - the element to look for
      Returns:
      true if found, false else

    • containsAny

      public static boolean containsAny(Collection source, Collection candidates)
      Return true if any element in 'candidates' is contained in 'source'; otherwise returns false.
      Parameters:
      source - the source Collection
      candidates - the candidates to search for
      Returns:
      whether any of the candidates has been found

    • findFirstMatch

      public static Object findFirstMatch(Collection source, Collection candidates)
      Return the first element in 'candidates' that is contained in 'source'. If no element in 'candidates' is present in 'source' returns null. Iteration order is Collection implementation specific.
      Parameters:
      source - the source Collection
      candidates - the candidates to search for
      Returns:
      the first present object, or null if not found

    • findFirstValueOfType

      public static <T> T findFirstValueOfType(Collection<?> collection, Class<T> type)
      Find the first single value of the given type in the given Collection or null if none was found
      Type Parameters:
      T - type type of object to find
      Parameters:
      collection - the Collection to search
      type - the type to look for
      Returns:
      a value of the given type found or null if none found.

    • findValueOfType

      public static Object findValueOfType(Collection<?> collection, Class<?>[] types)
      Find a single value of one of the given types in the given Collection: searching the Collection for a value of the first type, then searching for a value of the second type, etc.
      Parameters:
      collection - the collection to search
      types - the types to look for, in prioritized order
      Returns:
      a value of one of the given types found if there is a clear match, or null if none or more than one such value found

    • hasUniqueObject

      public static boolean hasUniqueObject(Collection collection)
      Determine whether the given Collection only contains a single unique object.
      Parameters:
      collection - the Collection to check
      Returns:
      true if the collection contains a single reference or multiple references to the same instance, false else

    • findCommonElementType

      public static Class<?> findCommonElementType(Collection collection)
      Find the common element type of the given Collection, if any.
      Parameters:
      collection - the Collection to check
      Returns:
      the common element type, or null if no clear common type has been found (or the collection was empty)

    • toArray

      public static <A, E extends A> A[] toArray(Enumeration<E> enumeration, A[] array)
      Marshal the elements from the given enumeration into an array of the given type. Enumeration elements must be assignable to the type of the given array. The array returned will be a different instance than the array given.
      Type Parameters:
      A - type of array
      E - type of enumeration
      Parameters:
      enumeration - source enumeration
      array - the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
      Returns:
      an array with the contents of the enumeration

    • toArray

      public static <T> T[] toArray(Collection<T> c, Class<T> type)

    • toIterator

      public static <E> Iterator<E> toIterator(Enumeration<E> enumeration)
      Adapt an enumeration to an iterator.
      Type Parameters:
      E - type of enumeration
      Parameters:
      enumeration - the enumeration
      Returns:
      the iterator