Package com.nomagic.utils

Class CollectionUtils

  • @OpenApiAll
public class CollectionUtils
extends java.lang.Object
    Collection related utility methods.

    • Constructor Summary

      Constructors 
      Constructor Description
      CollectionUtils()  

    • Method Summary

      All Methods Static Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      static <T> void addIfNotNull​(T element, java.util.Collection<T> collection)  
      static <T> java.util.Collection<T> append​(java.util.Collection<T> target, java.util.Collection<? extends T> source, boolean allowDuplication)
      Append source to target collection.
      static <T> java.util.Collection<T> append​(java.util.Collection<T> target, java.util.Iterator<? extends T> sourceIterator, boolean allowDuplication)
      Append source to target collection.
      static <T> java.util.Collection<T> append​(java.util.Collection<T> target, java.util.Iterator<? extends T> sourceIterator, boolean allowDuplication, boolean allowNulls)
      Append source to target collection.
      static <T> java.util.Collection<T> append​(java.util.Collection<T> target, T[] source, boolean allowDuplication)
      Append source array to target collection.
      static boolean contains​(java.util.Iterator it, java.lang.Object o)
      Checks if given iterator contains given object.
      static boolean containsAny​(java.util.Collection location, java.util.Collection what)
      Returns true if location contains any element from what
      static <S,​T,​C extends java.util.Collection<T>>
      C      		 convert​(java.util.Collection<S> source, C target, Converter<? super S,​? super T> converter)
      Convert one (source) collection into another (target) collection.
      static <C extends java.util.Collection<E>,​E>
      C      		 createCollection​(java.lang.Class<C> collection, java.util.Iterator<E> it)
      Creates given type collection and fills it with objects from given iterator
      static <T> java.util.Collection<T> createFromStringRepresentation​(java.lang.String string, java.lang.String delimiter, Converter<java.lang.String,​T> converter)
      Create collection from string.
      static <T> java.lang.String createStringRepresentation​(java.util.Collection<T> collection, java.lang.String delimiter, Converter<T,​java.lang.String> converter)
      Create string representation of given collection.
      static boolean equals​(java.util.Collection<?> collection1, java.util.Collection<?> collection2)
      Checks if both collections are equal - size the same and elements by order are the same
      static <T> java.util.List<T> filterByClassType​(java.util.Collection<?> input, java.lang.Class<T> type)
      Filters and casts collection from one type to another
      static void leaveElements​(java.util.List elements, int numberToLeave)
      Leaves a given number of first elements in the collection.
      static java.lang.String mapToString​(java.util.Map<java.lang.String,​java.lang.String> map)
      Serializes map to string.
      static <T> java.util.Collection<T> notDublicatedList​(java.util.Collection<T> collection)
      Deprecated.
      use notDuplicatedList(java.util.Collection)
      static <T> java.util.Collection<T> notDuplicatedList​(java.util.Collection<T> collection)
      Removes duplicates from given collection.
      static <T> void setFirstValue​(java.util.Collection<T> collection, T value)
      Set first value of the given collection.
      static <T> void setSingleValue​(java.util.Collection<T> collection, T value)
      Removes all values from a given collection and adds a new one.
      static java.util.Map<java.lang.String,​java.lang.String> stringToMap​(java.lang.String input)
      Deserialize map from string.
      static <T> java.util.Collection<T> toOptimizedCacheCollection​(java.util.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
      static <T> java.util.Collection<T> toOptimizedContainsCollection​(java.util.Collection<T> collection)
      Wrap the specified collection into containable collection that ensures optimized {{Collection.contains()}} performance.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • CollectionUtils

        public CollectionUtils()

    • Method Detail

      • convert

        public static <S,​T,​C extends java.util.Collection<T>> C convert​(java.util.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 converted element to 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> java.util.Collection<T> append​(java.util.Collection<T> target,
                                                 java.util.Collection<? extends T> source,
                                                 boolean allowDuplication)
        Append source to target collection.
        Parameters:
        target - target
        source - source
        allowDuplication - do not check for already added element if true
        Returns:
        appended collection

      • append

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

      • append

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

      • append

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

      • contains

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

      • containsAny

        public static boolean containsAny​(java.util.Collection location,
                                  java.util.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 java.util.Collection<E>,​E> C createCollection​(java.lang.Class<C> collection,
                                                                             java.util.Iterator<E> it)
        Creates 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> java.util.Collection<T> notDuplicatedList​(java.util.Collection<T> 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 col are list (sets cant have identical elements).
        Returns:
        collection.

      • notDublicatedList

        @Deprecated
public static <T> java.util.Collection<T> notDublicatedList​(java.util.Collection<T> collection)
        Deprecated.
        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 col are list (sets cant have identical elements).
        Returns:
        collection.

      • createStringRepresentation

        public static <T> java.lang.String createStringRepresentation​(java.util.Collection<T> collection,
                                                              java.lang.String delimiter,
                                                              Converter<T,​java.lang.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> java.util.Collection<T> createFromStringRepresentation​(java.lang.String string,
                                                                         java.lang.String delimiter,
                                                                         Converter<java.lang.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​(java.util.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 java.lang.String mapToString​(java.util.Map<java.lang.String,​java.lang.String> map)
        Serializes map to string.
        Parameters:
        map - map to serialize.
        Returns:
        string representation of the map.

      • stringToMap

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

      • filterByClassType

        public static <T> java.util.List<T> filterByClassType​(java.util.Collection<?> input,
                                                      java.lang.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

      • setSingleValue

        public static <T> void setSingleValue​(java.util.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​(java.util.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> java.util.Collection<T> toOptimizedContainsCollection​(java.util.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> java.util.Collection<T> toOptimizedCacheCollection​(java.util.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​(java.util.Collection<?> collection1,
                             java.util.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,
                                    java.util.Collection<T> collection)