Package com.nomagic.utils

Class CollectionUtils

java.lang.Object
com.nomagic.utils.CollectionUtils
@OpenApiAll public class CollectionUtils extends Object
Collection related utility methods.

  • Constructor Details

    • CollectionUtils

      public CollectionUtils()

  • Method Details

    • convert

      public static <S, T, C extends Collection<T>> C convert(Collection<S> source, C target, Converter<? super S,? super T> converter)
      Convert one (source) collection into another (target) collection. Converts each source element and adds a converted element to a target collection.
      Type Parameters:
      S - source collection element type.
      T - target collection element type.
      C - target collection type.
      Parameters:
      source - source collection.
      target - target collection.
      converter - converts each element.
      Returns:
      target collection.

    • append

      public static <T> Collection<T> append(Collection<T> target, Collection<? extends T> source, boolean allowDuplication)
      Append a source to a target collection.
      Parameters:
      target - target
      source - source
      allowDuplication - do not check for an already added element if true
      Returns:
      appended collection

    • append

      public static <T> Collection<T> append(Collection<T> target, Iterator<? extends T> sourceIterator, boolean allowDuplication)
      Append a source to a target collection.
      Parameters:
      target - target
      sourceIterator - source iterator.
      allowDuplication - do not check for an already added element if true
      Returns:
      appended collection

    • append

      public static <T> Collection<T> append(Collection<T> target, Iterator<? extends T> sourceIterator, boolean allowDuplication, boolean allowNulls)
      Append a source to a target collection.
      Parameters:
      target - target
      sourceIterator - source iterator.
      allowDuplication - do not check for an already added element if true
      allowNulls - allows nulls
      Returns:
      appended collection

    • append

      public static <T> Collection<T> append(Collection<T> target, T[] source, boolean allowDuplication)
      Append source array to a target collection.
      Parameters:
      target - target
      source - source
      allowDuplication - do not check for an already added element if true
      Returns:
      appended vector

    • contains

      public static boolean contains(Iterator it, Object o)
      Checks if given iterator contains a given object.
      Parameters:
      it - the iterator.
      o - the object.
      Returns:
      true, if it contains o.

    • containsAny

      public static boolean containsAny(Collection location, Collection what)
      Returns true if location contains any element from what
      Parameters:
      location - location collection
      what - what collection.
      Returns:
      boolean.

    • createCollection

      public static <C extends Collection<E>, E> C createCollection(Class<C> collection, Iterator<E> it)
      Creates a given type collection and fills it with objects from given iterator
      Parameters:
      collection - type collection.
      it - The given iterator.
      Returns:
      the result collection.

    • notDuplicatedList

      public static <T> Collection<T> notDuplicatedList(Collection<T> collection)
      Removes duplicates from a given collection. After remove, one element will be in collection only one time.
      Parameters:
      collection - collection to operate with (makes sense when col are list (sets cant have identical elements)).
      Returns:
      collection.

    • notDublicatedList

      @Deprecated(forRemoval=true) public static <T> Collection<T> notDublicatedList(Collection<T> collection)
      Deprecated, for removal: This API element is subject to removal in a future version.
      use notDuplicatedList(java.util.Collection)
      Removes duplicates from given collection. After remove one element will be in collection only one time.
      Parameters:
      collection - collection to operate with. Makes sense when collection is list (set cant have identical elements).
      Returns:
      collection.

    • createStringRepresentation

      public static <T> String createStringRepresentation(Collection<T> collection, String delimiter, Converter<T,String> converter)
      Create string representation of given collection.
      Parameters:
      collection - collection.
      delimiter - values delimiter.
      converter - convert object to string.
      Returns:
      string representation of collection.

    • createFromStringRepresentation

      public static <T> Collection<T> createFromStringRepresentation(String string, String delimiter, Converter<String,T> converter)
      Create collection from string.
      Parameters:
      string - string representation.
      delimiter - values delimiter.
      converter - convert string to object.
      Returns:
      collection.

    • leaveElements

      public static void leaveElements(List elements, int numberToLeave)
      Leaves a given number of first elements in the collection.
      Parameters:
      elements - elements to filter.
      numberToLeave - number of elements to leave.

    • mapToString

      public static String mapToString(Map<String,String> map)
      Serializes map to string.
      Parameters:
      map - map to serialize.
      Returns:
      string representation of the map.

    • stringToMap

      public static Map<String,String> stringToMap(String input)
      Deserialize map from string.
      Parameters:
      input - input string.
      Returns:
      map.

    • filterByClassType

      public static <T> List<T> filterByClassType(Collection<?> input, Class<T> type)
      Filters and casts collection from one type to another
      Type Parameters:
      T - type
      Parameters:
      input - input collection
      type - desired output collection type
      Returns:
      new typed list

    • filterByClassType

      public static <T> Stream<T> filterByClassType(Stream<?> stream, Class<T> type)
      Filter and map according given class.
      Parameters:
      stream - stream to filer and map
      type - desired output stream type
      Returns:
      filtered and mapped stream

    • findByClassType

      @CheckForNull public static <T> T findByClassType(Collection<?> input, Class<T> type)
      Looks for object of give class in the given collection.
      Type Parameters:
      T - type
      Parameters:
      input - input collection
      type - desired output collection type
      Returns:
      found object

    • find

      @CheckForNull public static <T> T find(Collection<T> input, Predicate<T> predicate)
      Looks for object matching given predicate.
      Parameters:
      input - input collection
      predicate - predicate to test
      Returns:
      found object

    • setSingleValue

      public static <T> void setSingleValue(Collection<T> collection, T value)
      Removes all values from a given collection and adds a new one.
      Parameters:
      collection - collection
      value - a new value

    • setFirstValue

      public static <T> void setFirstValue(Collection<T> collection, @CheckForNull T value)
      Set first value of the given collection. If collection is empty, adds a new value. If value is null, removes first value from collection.
      Parameters:
      collection - collection
      value - a new value

    • toOptimizedContainsCollection

      public static <T> Collection<T> toOptimizedContainsCollection(Collection<T> collection)
      Wrap the specified collection into containable collection that ensures optimized {{Collection.contains()}} performance. The provided collection should not change while the wrapped collection is used.
      Parameters:
      collection - a collection to wrap into containable collection
      Returns:
      return wrapped collection.

    • toOptimizedCacheCollection

      public static <T> Collection<T> toOptimizedCacheCollection(Collection<T> collection)
      Optimized for 1) minimal memory footprint, for the stored cache data to be as small as possible 2) contains() performance, while preserving iteration order and performance

      Returned collection in unmodifiable

    • equals

      public static boolean equals(Collection<?> collection1, Collection<?> collection2)
      Checks if both collections are equal - size the same and elements by order are the same
      Parameters:
      collection1 - first collection
      collection2 - second collection
      Returns:
      true if size the same and elements by order are the same

    • addIfNotNull

      public static <T> void addIfNotNull(@CheckForNull T element, Collection<T> collection)
      Adds the given element to the collection unless it is null.
      Parameters:
      element - nullable element to add
      collection - modifiable collection

    • copyAndAdd

      public static <T> List<T> copyAndAdd(@CheckForNull List<T> list, T element)
      Creates copy of the given list, or new list if null is provided. Then adds the given element and returns the copy.
      Parameters:
      element - element to add
      list - nullable list to create copy of
      Returns:
      copied and appended list

    • copyAndAdd

      public static <T> List<T> copyAndAdd(@CheckForNull List<T> list, Collection<T> toAdd)
      Creates copy of the given list, or new list if null is provided. Then adds the given collection at the end and returns the copy.
      Parameters:
      toAdd - collection to add
      list - nullable list to create copy of
      Returns:
      copied and appended list

    • startsWith

      public static <T> boolean startsWith(Collection<T> prefixCollection, Collection<T> collection)
      Checks if collection starts with prefixCollection Example: collection is "A.B.C", prefixCollection is "A.B". Result would be true.
      Parameters:
      prefixCollection - collection that is used to check if other collections starts with it
      collection - collection to check
      Returns:
      true if starts with prefixCollection, else false

    • listOf

      public static <T> List<T> listOf(@CheckForNull T element)
      Creates unmodifiable List with a given element. Or empty unmodifiable list if element is null.
      Type Parameters:
      T - any object
      Parameters:
      element - element
      Returns:
      list

    • listOf

      public static <T> List<T> listOf(@CheckForNull T element, List<T> list)
      Appends a given element to new unmodifiable List constructed from the given list. Returns the given list if an element is null.
      Type Parameters:
      T - any object
      Parameters:
      element - element
      list - list
      Returns:
      list