Class TreeSet<T>

java.lang.Object
io.vavr.collection.TreeSet<T>
Type Parameters:
T - Component type
All Implemented Interfaces:
Foldable<T>, Ordered<T>, Set<T>, SortedSet<T>, Traversable<T>, Function1<T,Boolean>, Value<T>, Serializable, Iterable<T>, Function<T,Boolean>

public final class TreeSet<T> extends Object implements SortedSet<T>, Serializable
SortedSet implementation, backed by a Red/Black Tree.
See Also:
  • Field Details

  • Constructor Details

  • Method Details

    • collector

      public static <T extends Comparable<? super T>> Collector<T,ArrayList<T>,TreeSet<T>> collector()
      Returns a Collector which may be used in conjunction with Stream.collect(java.util.stream.Collector) to obtain a TreeSet.

      The natural comparator is used to compare TreeSet elements.

      Type Parameters:
      T - Component type of the List.
      Returns:
      A io.vavr.collection.List Collector.
    • collector

      public static <T> Collector<T,ArrayList<T>,TreeSet<T>> collector(Comparator<? super T> comparator)
      Returns a Collector which may be used in conjunction with Stream.collect(java.util.stream.Collector) to obtain a TreeSet.
      Type Parameters:
      T - Component type of the List.
      Parameters:
      comparator - An element comparator
      Returns:
      A io.vavr.collection.List Collector.
    • empty

      public static <T extends Comparable<? super T>> TreeSet<T> empty()
    • empty

      public static <T> TreeSet<T> empty(Comparator<? super T> comparator)
    • narrow

      public static <T> TreeSet<T> narrow(TreeSet<? extends T> treeSet)
      Narrows a widened TreeSet<? extends T> to TreeSet<T> by performing a type-safe cast. This is eligible because immutable/read-only collections are covariant.

      CAUTION: The underlying Comparator might fail!

      Type Parameters:
      T - Component type of the TreeSet.
      Parameters:
      treeSet - A TreeSet.
      Returns:
      the given treeSet instance as narrowed type TreeSet<T>.
    • of

      public static <T extends Comparable<? super T>> TreeSet<T> of(T value)
    • of

      public static <T> TreeSet<T> of(Comparator<? super T> comparator, T value)
    • of

      @SafeVarargs public static <T extends Comparable<? super T>> TreeSet<T> of(T... values)
    • of

      @SafeVarargs public static <T> TreeSet<T> of(Comparator<? super T> comparator, T... values)
    • tabulate

      public static <T> TreeSet<T> tabulate(Comparator<? super T> comparator, int n, Function<? super Integer,? extends T> f)
      Returns a TreeSet containing n values of a given Function f over a range of integer values from 0 to n - 1.
      Type Parameters:
      T - Component type of the TreeSet
      Parameters:
      comparator - The comparator used to sort the elements
      n - The number of elements in the TreeSet
      f - The Function computing element values
      Returns:
      A TreeSet consisting of elements f(0),f(1), ..., f(n - 1)
      Throws:
      NullPointerException - if comparator or f are null
    • tabulate

      public static <T extends Comparable<? super T>> TreeSet<T> tabulate(int n, Function<? super Integer,? extends T> f)
      Returns a TreeSet containing n values of a given Function f over a range of integer values from 0 to n - 1. The underlying comparator is the natural comparator of T.
      Type Parameters:
      T - Component type of the TreeSet
      Parameters:
      n - The number of elements in the TreeSet
      f - The Function computing element values
      Returns:
      A TreeSet consisting of elements f(0),f(1), ..., f(n - 1)
      Throws:
      NullPointerException - if f is null
    • fill

      public static <T> TreeSet<T> fill(Comparator<? super T> comparator, int n, Supplier<? extends T> s)
      Returns a TreeSet containing tuples returned by n calls to a given Supplier s.
      Type Parameters:
      T - Component type of the TreeSet
      Parameters:
      comparator - The comparator used to sort the elements
      n - The number of elements in the TreeSet
      s - The Supplier computing element values
      Returns:
      A TreeSet of size n, where each element contains the result supplied by s.
      Throws:
      NullPointerException - if comparator or s are null
    • fill

      public static <T extends Comparable<? super T>> TreeSet<T> fill(int n, Supplier<? extends T> s)
      Returns a TreeSet containing tuples returned by n calls to a given Supplier s. The underlying comparator is the natural comparator of T.
      Type Parameters:
      T - Component type of the TreeSet
      Parameters:
      n - The number of elements in the TreeSet
      s - The Supplier computing element values
      Returns:
      A TreeSet of size n, where each element contains the result supplied by s.
      Throws:
      NullPointerException - if s is null
    • ofAll

      public static <T extends Comparable<? super T>> TreeSet<T> ofAll(Iterable<? extends T> values)
    • ofAll

      public static <T> TreeSet<T> ofAll(Comparator<? super T> comparator, Iterable<? extends T> values)
    • ofAll

      public static <T extends Comparable<? super T>> TreeSet<T> ofAll(Stream<? extends T> javaStream)
    • ofAll

      public static <T> TreeSet<T> ofAll(Comparator<? super T> comparator, Stream<? extends T> javaStream)
    • ofAll

      public static TreeSet<Boolean> ofAll(boolean... elements)
      Creates a TreeSet from boolean values.
      Parameters:
      elements - boolean values
      Returns:
      A new TreeSet of Boolean values
      Throws:
      NullPointerException - if elements is null
    • ofAll

      public static TreeSet<Byte> ofAll(byte... elements)
      Creates a TreeSet from byte values.
      Parameters:
      elements - byte values
      Returns:
      A new TreeSet of Byte values
      Throws:
      NullPointerException - if elements is null
    • ofAll

      public static TreeSet<Character> ofAll(char... elements)
      Creates a TreeSet from char values.
      Parameters:
      elements - char values
      Returns:
      A new TreeSet of Character values
      Throws:
      NullPointerException - if elements is null
    • ofAll

      public static TreeSet<Double> ofAll(double... elements)
      Creates a TreeSet from double values.
      Parameters:
      elements - double values
      Returns:
      A new TreeSet of Double values
      Throws:
      NullPointerException - if elements is null
    • ofAll

      public static TreeSet<Float> ofAll(float... elements)
      Creates a TreeSet from float values.
      Parameters:
      elements - float values
      Returns:
      A new TreeSet of Float values
      Throws:
      NullPointerException - if elements is null
    • ofAll

      public static TreeSet<Integer> ofAll(int... elements)
      Creates a TreeSet from int values.
      Parameters:
      elements - int values
      Returns:
      A new TreeSet of Integer values
      Throws:
      NullPointerException - if elements is null
    • ofAll

      public static TreeSet<Long> ofAll(long... elements)
      Creates a TreeSet from long values.
      Parameters:
      elements - long values
      Returns:
      A new TreeSet of Long values
      Throws:
      NullPointerException - if elements is null
    • ofAll

      public static TreeSet<Short> ofAll(short... elements)
      Creates a TreeSet from short values.
      Parameters:
      elements - short values
      Returns:
      A new TreeSet of Short values
      Throws:
      NullPointerException - if elements is null
    • range

      public static TreeSet<Integer> range(int from, int toExclusive)
      Creates a TreeSet of int numbers starting from from, extending to toExclusive - 1.

      Examples:

       
       TreeSet.range(0, 0)  // = TreeSet()
       TreeSet.range(2, 0)  // = TreeSet()
       TreeSet.range(-2, 2) // = TreeSet(-2, -1, 0, 1)
       
       
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      Returns:
      a range of int values as specified or the empty range if from >= toExclusive
    • range

      public static TreeSet<Character> range(char from, char toExclusive)
    • rangeBy

      public static TreeSet<Integer> rangeBy(int from, int toExclusive, int step)
      Creates a TreeSet of int numbers starting from from, extending to toExclusive - 1, with step.

      Examples:

       
       TreeSet.rangeBy(1, 3, 1)  // = TreeSet(1, 2)
       TreeSet.rangeBy(1, 4, 2)  // = TreeSet(1, 3)
       TreeSet.rangeBy(4, 1, -2) // = TreeSet(4, 2)
       TreeSet.rangeBy(4, 1, 2)  // = TreeSet()
       
       
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      step - the step
      Returns:
      a range of long values as specified or the empty range if
      from >= toInclusive and step > 0 or
      from <= toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero
    • rangeBy

      public static TreeSet<Character> rangeBy(char from, char toExclusive, int step)
    • rangeBy

      @GwtIncompatible public static TreeSet<Double> rangeBy(double from, double toExclusive, double step)
    • range

      public static TreeSet<Long> range(long from, long toExclusive)
      Creates a TreeSet of long numbers starting from from, extending to toExclusive - 1.

      Examples:

       
       TreeSet.range(0L, 0L)  // = TreeSet()
       TreeSet.range(2L, 0L)  // = TreeSet()
       TreeSet.range(-2L, 2L) // = TreeSet(-2L, -1L, 0L, 1L)
       
       
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      Returns:
      a range of long values as specified or the empty range if from >= toExclusive
    • rangeBy

      public static TreeSet<Long> rangeBy(long from, long toExclusive, long step)
      Creates a TreeSet of long numbers starting from from, extending to toExclusive - 1, with step.

      Examples:

       
       TreeSet.rangeBy(1L, 3L, 1L)  // = TreeSet(1L, 2L)
       TreeSet.rangeBy(1L, 4L, 2L)  // = TreeSet(1L, 3L)
       TreeSet.rangeBy(4L, 1L, -2L) // = TreeSet(4L, 2L)
       TreeSet.rangeBy(4L, 1L, 2L)  // = TreeSet()
       
       
      Parameters:
      from - the first number
      toExclusive - the last number + 1
      step - the step
      Returns:
      a range of long values as specified or the empty range if
      from >= toInclusive and step > 0 or
      from <= toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero
    • rangeClosed

      public static TreeSet<Integer> rangeClosed(int from, int toInclusive)
      Creates a TreeSet of int numbers starting from from, extending to toInclusive.

      Examples:

       
       TreeSet.rangeClosed(0, 0)  // = TreeSet(0)
       TreeSet.rangeClosed(2, 0)  // = TreeSet()
       TreeSet.rangeClosed(-2, 2) // = TreeSet(-2, -1, 0, 1, 2)
       
       
      Parameters:
      from - the first number
      toInclusive - the last number
      Returns:
      a range of int values as specified or the empty range if from > toInclusive
    • rangeClosed

      public static TreeSet<Character> rangeClosed(char from, char toInclusive)
    • rangeClosedBy

      public static TreeSet<Integer> rangeClosedBy(int from, int toInclusive, int step)
      Creates a TreeSet of int numbers starting from from, extending to toInclusive, with step.

      Examples:

       
       TreeSet.rangeClosedBy(1, 3, 1)  // = TreeSet(1, 2, 3)
       TreeSet.rangeClosedBy(1, 4, 2)  // = TreeSet(1, 3)
       TreeSet.rangeClosedBy(4, 1, -2) // = TreeSet(4, 2)
       TreeSet.rangeClosedBy(4, 1, 2)  // = TreeSet()
       
       
      Parameters:
      from - the first number
      toInclusive - the last number
      step - the step
      Returns:
      a range of int values as specified or the empty range if
      from > toInclusive and step > 0 or
      from < toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero
    • rangeClosedBy

      public static TreeSet<Character> rangeClosedBy(char from, char toInclusive, int step)
    • rangeClosedBy

      @GwtIncompatible public static TreeSet<Double> rangeClosedBy(double from, double toInclusive, double step)
    • rangeClosed

      public static TreeSet<Long> rangeClosed(long from, long toInclusive)
      Creates a TreeSet of long numbers starting from from, extending to toInclusive.

      Examples:

       
       TreeSet.rangeClosed(0L, 0L)  // = TreeSet(0L)
       TreeSet.rangeClosed(2L, 0L)  // = TreeSet()
       TreeSet.rangeClosed(-2L, 2L) // = TreeSet(-2L, -1L, 0L, 1L, 2L)
       
       
      Parameters:
      from - the first number
      toInclusive - the last number
      Returns:
      a range of long values as specified or the empty range if from > toInclusive
    • rangeClosedBy

      public static TreeSet<Long> rangeClosedBy(long from, long toInclusive, long step)
      Creates a TreeSet of long numbers starting from from, extending to toInclusive, with step.

      Examples:

       
       TreeSet.rangeClosedBy(1L, 3L, 1L)  // = TreeSet(1L, 2L, 3L)
       TreeSet.rangeClosedBy(1L, 4L, 2L)  // = TreeSet(1L, 3L)
       TreeSet.rangeClosedBy(4L, 1L, -2L) // = TreeSet(4L, 2L)
       TreeSet.rangeClosedBy(4L, 1L, 2L)  // = TreeSet()
       
       
      Parameters:
      from - the first number
      toInclusive - the last number
      step - the step
      Returns:
      a range of int values as specified or the empty range if
      from > toInclusive and step > 0 or
      from < toInclusive and step < 0
      Throws:
      IllegalArgumentException - if step is zero
    • add

      public TreeSet<T> add(T element)
      Description copied from interface: Set
      Add the given element to this set, if it is not already contained.
      Specified by:
      add in interface Set<T>
      Specified by:
      add in interface SortedSet<T>
      Parameters:
      element - The element to be added.
      Returns:
      A new set containing all elements of this set and also element.
    • addAll

      public TreeSet<T> addAll(Iterable<? extends T> elements)
      Description copied from interface: Set
      Adds all of the given elements to this set, if not already contained.
      Specified by:
      addAll in interface Set<T>
      Specified by:
      addAll in interface SortedSet<T>
      Parameters:
      elements - The elements to be added.
      Returns:
      A new set containing all elements of this set and the given elements, if not already contained.
    • collect

      public <R> TreeSet<R> collect(PartialFunction<? super T,? extends R> partialFunction)
      Description copied from interface: Traversable
      Collects all elements that are in the domain of the given partialFunction by mapping the elements to type R.

      More specifically, for each of this elements in iteration order first it is checked

      
       partialFunction.isDefinedAt(element)
       
      If the elements makes it through that filter, the mapped instance is added to the result collection
      
       R newElement = partialFunction.apply(element)
       
      Note:If this Traversable is ordered (i.e. extends Ordered, the caller of collect has to ensure that the elements are comparable (i.e. extend Comparable).
      Specified by:
      collect in interface Set<T>
      Specified by:
      collect in interface SortedSet<T>
      Specified by:
      collect in interface Traversable<T>
      Type Parameters:
      R - The new element type
      Parameters:
      partialFunction - A function that is not necessarily defined of all elements of this traversable.
      Returns:
      A new Traversable instance containing elements of type R
    • comparator

      public Comparator<T> comparator()
      Description copied from interface: Ordered
      Returns the comparator which defines the order of the elements contained in this collection.
      Specified by:
      comparator in interface Ordered<T>
      Returns:
      The comparator that defines the order of this collection's elements.
    • diff

      public TreeSet<T> diff(Set<? extends T> elements)
      Description copied from interface: Set
      Calculates the difference between this set and another set.

      See also Set.removeAll(Iterable).

      Specified by:
      diff in interface Set<T>
      Specified by:
      diff in interface SortedSet<T>
      Parameters:
      elements - Elements to be removed from this set.
      Returns:
      A new Set containing all elements of this set which are not located in that set.
    • contains

      public boolean contains(T element)
      Description copied from interface: Value
      Shortcut for exists(e -> Objects.equals(e, element)), tests if the given element is contained.
      Specified by:
      contains in interface Set<T>
      Specified by:
      contains in interface Value<T>
      Parameters:
      element - An Object of type A, may be null.
      Returns:
      true, if element is contained, false otherwise.
    • distinct

      public TreeSet<T> distinct()
      Description copied from interface: Traversable
      Returns a new version of this which contains no duplicates. Elements are compared using equals.
      Specified by:
      distinct in interface Set<T>
      Specified by:
      distinct in interface SortedSet<T>
      Specified by:
      distinct in interface Traversable<T>
      Returns:
      a new Traversable containing this elements without duplicates
    • distinctBy

      public TreeSet<T> distinctBy(Comparator<? super T> comparator)
      Description copied from interface: Traversable
      Returns a new version of this which contains no duplicates. Elements are compared using the given comparator.
      Specified by:
      distinctBy in interface Set<T>
      Specified by:
      distinctBy in interface SortedSet<T>
      Specified by:
      distinctBy in interface Traversable<T>
      Parameters:
      comparator - A comparator
      Returns:
      a new Traversable containing this elements without duplicates
    • distinctBy

      public <U> TreeSet<T> distinctBy(Function<? super T,? extends U> keyExtractor)
      Description copied from interface: Traversable
      Returns a new version of this which contains no duplicates. Elements mapped to keys which are compared using equals.

      The elements of the result are determined in the order of their occurrence - first match wins.

      Specified by:
      distinctBy in interface Set<T>
      Specified by:
      distinctBy in interface SortedSet<T>
      Specified by:
      distinctBy in interface Traversable<T>
      Type Parameters:
      U - key type
      Parameters:
      keyExtractor - A key extractor
      Returns:
      a new Traversable containing this elements without duplicates
    • drop

      public TreeSet<T> drop(int n)
      Description copied from interface: Traversable
      Drops the first n elements of this or all elements, if this length < n.
      Specified by:
      drop in interface Set<T>
      Specified by:
      drop in interface SortedSet<T>
      Specified by:
      drop in interface Traversable<T>
      Parameters:
      n - The number of elements to drop.
      Returns:
      a new instance consisting of all elements of this except the first n ones, or else the empty instance, if this has less than n elements.
    • dropRight

      public TreeSet<T> dropRight(int n)
      Description copied from interface: Traversable
      Drops the last n elements of this or all elements, if this length < n.
      Specified by:
      dropRight in interface Set<T>
      Specified by:
      dropRight in interface SortedSet<T>
      Specified by:
      dropRight in interface Traversable<T>
      Parameters:
      n - The number of elements to drop.
      Returns:
      a new instance consisting of all elements of this except the last n ones, or else the empty instance, if this has less than n elements.
    • dropUntil

      public TreeSet<T> dropUntil(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Drops elements until the predicate holds for the current element.
      Specified by:
      dropUntil in interface Set<T>
      Specified by:
      dropUntil in interface SortedSet<T>
      Specified by:
      dropUntil in interface Traversable<T>
      Parameters:
      predicate - A condition tested subsequently for this elements.
      Returns:
      a new instance consisting of all elements starting from the first one which does satisfy the given predicate.
    • dropWhile

      public TreeSet<T> dropWhile(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Drops elements while the predicate holds for the current element.

      Note: This is essentially the same as dropUntil(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

      Specified by:
      dropWhile in interface Set<T>
      Specified by:
      dropWhile in interface SortedSet<T>
      Specified by:
      dropWhile in interface Traversable<T>
      Parameters:
      predicate - A condition tested subsequently for this elements.
      Returns:
      a new instance consisting of all elements starting from the first one which does not satisfy the given predicate.
    • filter

      public TreeSet<T> filter(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Returns a new traversable consisting of all elements which satisfy the given predicate.
      Specified by:
      filter in interface Set<T>
      Specified by:
      filter in interface SortedSet<T>
      Specified by:
      filter in interface Traversable<T>
      Parameters:
      predicate - A predicate
      Returns:
      a new traversable
    • reject

      public TreeSet<T> reject(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Returns a new traversable consisting of all elements which do not satisfy the given predicate.

      The default implementation is equivalent to

      filter(predicate.negate()
      Specified by:
      reject in interface Set<T>
      Specified by:
      reject in interface SortedSet<T>
      Specified by:
      reject in interface Traversable<T>
      Parameters:
      predicate - A predicate
      Returns:
      a new traversable
    • flatMap

      public <U> TreeSet<U> flatMap(Comparator<? super U> comparator, Function<? super T,? extends Iterable<? extends U>> mapper)
      Description copied from interface: SortedSet
      Same as SortedSet.flatMap(Function) but using a specific comparator for values of the codomain of the given mapper.
      Specified by:
      flatMap in interface SortedSet<T>
      Type Parameters:
      U - Type of flat-mapped values
      Parameters:
      comparator - A comparator for values of type U
      mapper - A function which maps values of type T to Iterables of values of type U
      Returns:
      A new Set instance containing mapped values
    • flatMap

      public <U> TreeSet<U> flatMap(Function<? super T,? extends Iterable<? extends U>> mapper)
      Description copied from interface: Traversable
      FlatMaps this Traversable.
      Specified by:
      flatMap in interface Set<T>
      Specified by:
      flatMap in interface SortedSet<T>
      Specified by:
      flatMap in interface Traversable<T>
      Type Parameters:
      U - The resulting component type.
      Parameters:
      mapper - A mapper
      Returns:
      A new Traversable instance.
    • foldRight

      public <U> U foldRight(U zero, BiFunction<? super T,? super U,? extends U> f)
      Description copied from interface: Foldable
      Folds this elements from the right, starting with zero and successively calling combine.

      Example:

       
       // = "!cba"
       List("a", "b", "c").foldRight("!", (x, xs) -> xs + x)
        
      Specified by:
      foldRight in interface Foldable<T>
      Specified by:
      foldRight in interface Traversable<T>
      Type Parameters:
      U - the type of the folded value
      Parameters:
      zero - A zero element to start with.
      f - A function which combines elements.
      Returns:
      a folded value
    • groupBy

      public <C> Map<C,TreeSet<T>> groupBy(Function<? super T,? extends C> classifier)
      Description copied from interface: Traversable
      Groups this elements by classifying the elements.
      Specified by:
      groupBy in interface Set<T>
      Specified by:
      groupBy in interface SortedSet<T>
      Specified by:
      groupBy in interface Traversable<T>
      Type Parameters:
      C - classified class type
      Parameters:
      classifier - A function which classifies elements into classes
      Returns:
      A Map containing the grouped elements
      See Also:
    • grouped

      public Iterator<TreeSet<T>> grouped(int size)
      Description copied from interface: Traversable
      Groups this Traversable into fixed size blocks.

      Let length be the length of this Iterable. Then grouped is defined as follows:

      • If this.isEmpty(), the resulting Iterator is empty.
      • If size <= length, the resulting Iterator will contain length / size blocks of size size and maybe a non-empty block of size length % size, if there are remaining elements.
      • If size > length, the resulting Iterator will contain one block of size length.
      Examples:
       
       [].grouped(1) = []
       [].grouped(0) throws
       [].grouped(-1) throws
       [1,2,3,4].grouped(2) = [[1,2],[3,4]]
       [1,2,3,4,5].grouped(2) = [[1,2],[3,4],[5]]
       [1,2,3,4].grouped(5) = [[1,2,3,4]]
       
       
      Please note that grouped(int) is a special case of Traversable.sliding(int, int), i.e. grouped(size) is the same as sliding(size, size).
      Specified by:
      grouped in interface Set<T>
      Specified by:
      grouped in interface SortedSet<T>
      Specified by:
      grouped in interface Traversable<T>
      Parameters:
      size - a positive block size
      Returns:
      A new Iterator of grouped blocks of the given size
    • hasDefiniteSize

      public boolean hasDefiniteSize()
      Description copied from interface: Traversable
      Checks if this Traversable is known to have a finite size.

      This method should be implemented by classes only, i.e. not by interfaces.

      Specified by:
      hasDefiniteSize in interface Traversable<T>
      Returns:
      true, if this Traversable is known to have a finite size, false otherwise.
    • head

      public T head()
      Description copied from interface: Traversable
      Returns the first element of a non-empty Traversable.
      Specified by:
      head in interface Traversable<T>
      Returns:
      The first element of this Traversable.
    • headOption

      public Option<T> headOption()
      Description copied from interface: Traversable
      Returns the first element of a non-empty Traversable as Option.
      Specified by:
      headOption in interface Traversable<T>
      Returns:
      Some(element) or None if this is empty.
    • init

      public TreeSet<T> init()
      Description copied from interface: Traversable
      Dual of Traversable.tail(), returning all elements except the last.
      Specified by:
      init in interface Set<T>
      Specified by:
      init in interface SortedSet<T>
      Specified by:
      init in interface Traversable<T>
      Returns:
      a new instance containing all elements except the last.
    • initOption

      public Option<TreeSet<T>> initOption()
      Description copied from interface: Traversable
      Dual of Traversable.tailOption(), returning all elements except the last as Option.
      Specified by:
      initOption in interface Set<T>
      Specified by:
      initOption in interface SortedSet<T>
      Specified by:
      initOption in interface Traversable<T>
      Returns:
      Some(traversable) or None if this is empty.
    • intersect

      public TreeSet<T> intersect(Set<? extends T> elements)
      Description copied from interface: Set
      Computes the intersection between this set and another set.

      See also Set.retainAll(Iterable).

      Specified by:
      intersect in interface Set<T>
      Specified by:
      intersect in interface SortedSet<T>
      Parameters:
      elements - the set to intersect with.
      Returns:
      A new Set consisting of all elements that are both in this set and in the given set that.
    • isAsync

      public boolean isAsync()
      A TreeSet is computed synchronously.
      Specified by:
      isAsync in interface Value<T>
      Returns:
      false
    • isEmpty

      public boolean isEmpty()
      Description copied from interface: Traversable
      Checks if this Traversable is empty.
      Specified by:
      isEmpty in interface Traversable<T>
      Specified by:
      isEmpty in interface Value<T>
      Returns:
      true, if this Traversable contains no elements, false otherwise.
    • isLazy

      public boolean isLazy()
      A TreeSet is computed eagerly.
      Specified by:
      isLazy in interface Value<T>
      Returns:
      false
    • isTraversableAgain

      public boolean isTraversableAgain()
      Description copied from interface: Traversable
      Checks if this Traversable can be repeatedly traversed.

      This method should be implemented by classes only, i.e. not by interfaces.

      Specified by:
      isTraversableAgain in interface Traversable<T>
      Returns:
      true, if this Traversable is known to be traversable repeatedly, false otherwise.
    • iterator

      public Iterator<T> iterator()
      Description copied from interface: Traversable
      An iterator by means of head() and tail(). Subclasses may want to override this method.
      Specified by:
      iterator in interface Iterable<T>
      Specified by:
      iterator in interface Set<T>
      Specified by:
      iterator in interface Traversable<T>
      Specified by:
      iterator in interface Value<T>
      Returns:
      A new Iterator of this Traversable elements.
    • last

      public T last()
      Description copied from interface: Traversable
      Dual of Traversable.head(), returning the last element.
      Specified by:
      last in interface Traversable<T>
      Returns:
      the last element.
    • length

      public int length()
      Description copied from interface: Traversable
      Computes the number of elements of this Traversable.

      Same as Traversable.size().

      Specified by:
      length in interface Set<T>
      Specified by:
      length in interface Traversable<T>
      Returns:
      the number of elements
    • map

      public <U> TreeSet<U> map(Comparator<? super U> comparator, Function<? super T,? extends U> mapper)
      Description copied from interface: SortedSet
      Same as SortedSet.map(Function) but using a specific comparator for values of the codomain of the given mapper.
      Specified by:
      map in interface SortedSet<T>
      Type Parameters:
      U - Type of mapped values
      Parameters:
      comparator - A comparator for values of type U
      mapper - A function which maps values of type T to values of type U
      Returns:
      A new Set instance containing mapped values
    • map

      public <U> TreeSet<U> map(Function<? super T,? extends U> mapper)
      Description copied from interface: Traversable
      Maps the elements of this Traversable to elements of a new type preserving their order, if any.
      Specified by:
      map in interface Set<T>
      Specified by:
      map in interface SortedSet<T>
      Specified by:
      map in interface Traversable<T>
      Specified by:
      map in interface Value<T>
      Type Parameters:
      U - Component type of the target Traversable
      Parameters:
      mapper - A mapper.
      Returns:
      a mapped Traversable
    • orElse

      public TreeSet<T> orElse(Iterable<? extends T> other)
      Returns this TreeSet if it is nonempty, otherwise TreeSet created from iterable, using existing comparator.
      Specified by:
      orElse in interface Set<T>
      Specified by:
      orElse in interface SortedSet<T>
      Specified by:
      orElse in interface Traversable<T>
      Parameters:
      other - An alternative Traversable
      Returns:
      this TreeSet if it is nonempty, otherwise TreeSet created from iterable, using existing comparator.
    • orElse

      public TreeSet<T> orElse(Supplier<? extends Iterable<? extends T>> supplier)
      Returns this TreeSet if it is nonempty, otherwise TreeSet created from result of evaluating supplier, using existing comparator.
      Specified by:
      orElse in interface Set<T>
      Specified by:
      orElse in interface SortedSet<T>
      Specified by:
      orElse in interface Traversable<T>
      Parameters:
      supplier - An alternative Traversable
      Returns:
      this TreeSet if it is nonempty, otherwise TreeSet created from result of evaluating supplier, using existing comparator.
    • partition

      public Tuple2<TreeSet<T>,TreeSet<T>> partition(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Creates a partition of this Traversable by splitting this elements in two in distinct traversables according to a predicate.
      Specified by:
      partition in interface Set<T>
      Specified by:
      partition in interface SortedSet<T>
      Specified by:
      partition in interface Traversable<T>
      Parameters:
      predicate - A predicate which classifies an element if it is in the first or the second traversable.
      Returns:
      A disjoint union of two traversables. The first Traversable contains all elements that satisfy the given predicate, the second Traversable contains all elements that don't. The original order of elements is preserved.
    • peek

      public TreeSet<T> peek(Consumer<? super T> action)
      Description copied from interface: Value
      Performs the given action on the first element if this is an eager implementation. Performs the given action on all elements (the first immediately, successive deferred), if this is a lazy implementation.
      Specified by:
      peek in interface Set<T>
      Specified by:
      peek in interface SortedSet<T>
      Specified by:
      peek in interface Traversable<T>
      Specified by:
      peek in interface Value<T>
      Parameters:
      action - The action that will be performed on the element(s).
      Returns:
      this instance
    • remove

      public TreeSet<T> remove(T element)
      Description copied from interface: Set
      Removes a specific element from this set, if present.
      Specified by:
      remove in interface Set<T>
      Specified by:
      remove in interface SortedSet<T>
      Parameters:
      element - The element to be removed from this set.
      Returns:
      A new set consisting of the elements of this set, without the given element.
    • removeAll

      public TreeSet<T> removeAll(Iterable<? extends T> elements)
      Description copied from interface: Set
      Removes all of the given elements from this set, if present.
      Specified by:
      removeAll in interface Set<T>
      Specified by:
      removeAll in interface SortedSet<T>
      Parameters:
      elements - The elements to be removed from this set.
      Returns:
      A new set consisting of the elements of this set, without the given elements.
    • replace

      public TreeSet<T> replace(T currentElement, T newElement)
      Description copied from interface: Traversable
      Replaces the first occurrence (if exists) of the given currentElement with newElement.
      Specified by:
      replace in interface Set<T>
      Specified by:
      replace in interface SortedSet<T>
      Specified by:
      replace in interface Traversable<T>
      Parameters:
      currentElement - An element to be substituted.
      newElement - A replacement for currentElement.
      Returns:
      a Traversable containing all elements of this where the first occurrence of currentElement is replaced with newElement.
    • replaceAll

      public TreeSet<T> replaceAll(T currentElement, T newElement)
      Description copied from interface: Traversable
      Replaces all occurrences of the given currentElement with newElement.
      Specified by:
      replaceAll in interface Set<T>
      Specified by:
      replaceAll in interface SortedSet<T>
      Specified by:
      replaceAll in interface Traversable<T>
      Parameters:
      currentElement - An element to be substituted.
      newElement - A replacement for currentElement.
      Returns:
      a Traversable containing all elements of this where all occurrences of currentElement are replaced with newElement.
    • retainAll

      public TreeSet<T> retainAll(Iterable<? extends T> elements)
      Description copied from interface: Traversable
      Keeps all occurrences of the given elements from this.
      Specified by:
      retainAll in interface Set<T>
      Specified by:
      retainAll in interface SortedSet<T>
      Specified by:
      retainAll in interface Traversable<T>
      Parameters:
      elements - Elements to be kept.
      Returns:
      a Traversable containing all occurrences of the given elements.
    • scan

      public TreeSet<T> scan(T zero, BiFunction<? super T,? super T,? extends T> operation)
      Description copied from interface: Traversable
      Computes a prefix scan of the elements of the collection. Note: The neutral element z may be applied more than once.
      Specified by:
      scan in interface Set<T>
      Specified by:
      scan in interface SortedSet<T>
      Specified by:
      scan in interface Traversable<T>
      Parameters:
      zero - neutral element for the operator op
      operation - the associative operator for the scan
      Returns:
      a new traversable collection containing the prefix scan of the elements in this traversable collection
    • scanLeft

      public <U> Set<U> scanLeft(U zero, BiFunction<? super U,? super T,? extends U> operation)
      Description copied from interface: Traversable
      Produces a collection containing cumulative results of applying the operator going left to right. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.
      Specified by:
      scanLeft in interface Set<T>
      Specified by:
      scanLeft in interface SortedSet<T>
      Specified by:
      scanLeft in interface Traversable<T>
      Type Parameters:
      U - the type of the elements in the resulting collection
      Parameters:
      zero - the initial value
      operation - the binary operator applied to the intermediate result and the element
      Returns:
      collection with intermediate results
    • scanRight

      public <U> Set<U> scanRight(U zero, BiFunction<? super T,? super U,? extends U> operation)
      Description copied from interface: Traversable
      Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result. Note: will not terminate for infinite-sized collections. Note: might return different results for different runs, unless the underlying collection type is ordered.
      Specified by:
      scanRight in interface Set<T>
      Specified by:
      scanRight in interface SortedSet<T>
      Specified by:
      scanRight in interface Traversable<T>
      Type Parameters:
      U - the type of the elements in the resulting collection
      Parameters:
      zero - the initial value
      operation - the binary operator applied to the intermediate result and the element
      Returns:
      collection with intermediate results
    • slideBy

      public Iterator<TreeSet<T>> slideBy(Function<? super T,?> classifier)
      Description copied from interface: Traversable
      Slides a non-overlapping window of a variable size over this Traversable.

      Each window contains elements with the same class, as determined by classifier. Two consecutive values in this Traversable will be in the same window only if classifier returns equal values for them. Otherwise, the values will constitute the last element of the previous window and the first element of the next window.

      Examples:

      
       [].slideBy(Function.identity()) = []
       [1,2,3,4,4,5].slideBy(Function.identity()) = [[1],[2],[3],[4,4],[5]]
       [1,2,3,10,12,5,7,20,29].slideBy(x -> x/10) = [[1,2,3],[10,12],[5,7],[20,29]]
       
      Specified by:
      slideBy in interface Set<T>
      Specified by:
      slideBy in interface SortedSet<T>
      Specified by:
      slideBy in interface Traversable<T>
      Parameters:
      classifier - A function which classifies elements into classes
      Returns:
      A new Iterator of windows of the grouped elements
    • sliding

      public Iterator<TreeSet<T>> sliding(int size)
      Description copied from interface: Traversable
      Slides a window of a specific size and step size 1 over this Traversable by calling Traversable.sliding(int, int).
      Specified by:
      sliding in interface Set<T>
      Specified by:
      sliding in interface SortedSet<T>
      Specified by:
      sliding in interface Traversable<T>
      Parameters:
      size - a positive window size
      Returns:
      a new Iterator of windows of a specific size using step size 1
    • sliding

      public Iterator<TreeSet<T>> sliding(int size, int step)
      Description copied from interface: Traversable
      Slides a window of a specific size and step size over this Traversable.

      Examples:

       
       [].sliding(1,1) = []
       [1,2,3,4,5].sliding(2,3) = [[1,2],[4,5]]
       [1,2,3,4,5].sliding(2,4) = [[1,2],[5]]
       [1,2,3,4,5].sliding(2,5) = [[1,2]]
       [1,2,3,4].sliding(5,3) = [[1,2,3,4],[4]]
       
       
      Specified by:
      sliding in interface Set<T>
      Specified by:
      sliding in interface SortedSet<T>
      Specified by:
      sliding in interface Traversable<T>
      Parameters:
      size - a positive window size
      step - a positive step size
      Returns:
      a new Iterator of windows of a specific size using a specific step size
    • span

      public Tuple2<TreeSet<T>,TreeSet<T>> span(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Returns a tuple where the first element is the longest prefix of elements that satisfy the given predicate and the second element is the remainder.
      Specified by:
      span in interface Set<T>
      Specified by:
      span in interface SortedSet<T>
      Specified by:
      span in interface Traversable<T>
      Parameters:
      predicate - A predicate.
      Returns:
      a Tuple containing the longest prefix of elements that satisfy p and the remainder.
    • tail

      public TreeSet<T> tail()
      Description copied from interface: Traversable
      Drops the first element of a non-empty Traversable.
      Specified by:
      tail in interface Set<T>
      Specified by:
      tail in interface SortedSet<T>
      Specified by:
      tail in interface Traversable<T>
      Returns:
      A new instance of Traversable containing all elements except the first.
    • tailOption

      public Option<TreeSet<T>> tailOption()
      Description copied from interface: Traversable
      Drops the first element of a non-empty Traversable and returns an Option.
      Specified by:
      tailOption in interface Set<T>
      Specified by:
      tailOption in interface SortedSet<T>
      Specified by:
      tailOption in interface Traversable<T>
      Returns:
      Some(traversable) or None if this is empty.
    • take

      public TreeSet<T> take(int n)
      Description copied from interface: Traversable
      Takes the first n elements of this or all elements, if this length < n.

      The result is equivalent to sublist(0, max(0, min(length(), n))) but does not throw if n < 0 or n > length().

      In the case of n < 0 the empty instance is returned, in the case of n > length() this is returned.

      Specified by:
      take in interface Set<T>
      Specified by:
      take in interface SortedSet<T>
      Specified by:
      take in interface Traversable<T>
      Parameters:
      n - The number of elements to take.
      Returns:
      A new instance consisting of the first n elements of this or all elements, if this has less than n elements.
    • takeRight

      public TreeSet<T> takeRight(int n)
      Description copied from interface: Traversable
      Takes the last n elements of this or all elements, if this length < n.

      The result is equivalent to sublist(max(0, min(length(), length() - n)), n), i.e. takeRight will not throw if n < 0 or n > length().

      In the case of n < 0 the empty instance is returned, in the case of n > length() this is returned.

      Specified by:
      takeRight in interface Set<T>
      Specified by:
      takeRight in interface SortedSet<T>
      Specified by:
      takeRight in interface Traversable<T>
      Parameters:
      n - The number of elements to take.
      Returns:
      A new instance consisting of the last n elements of this or all elements, if this has less than n elements.
    • takeUntil

      public TreeSet<T> takeUntil(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Takes elements until the predicate holds for the current element.

      Note: This is essentially the same as takeWhile(predicate.negate()). It is intended to be used with method references, which cannot be negated directly.

      Specified by:
      takeUntil in interface Set<T>
      Specified by:
      takeUntil in interface SortedSet<T>
      Specified by:
      takeUntil in interface Traversable<T>
      Parameters:
      predicate - A condition tested subsequently for this elements.
      Returns:
      a new instance consisting of all elements before the first one which does satisfy the given predicate.
    • takeWhile

      public TreeSet<T> takeWhile(Predicate<? super T> predicate)
      Description copied from interface: Traversable
      Takes elements while the predicate holds for the current element.
      Specified by:
      takeWhile in interface Set<T>
      Specified by:
      takeWhile in interface SortedSet<T>
      Specified by:
      takeWhile in interface Traversable<T>
      Parameters:
      predicate - A condition tested subsequently for the contained elements.
      Returns:
      a new instance consisting of all elements before the first one which does not satisfy the given predicate.
    • transform

      public <U> U transform(Function<? super TreeSet<T>,? extends U> f)
      Transforms this TreeSet.
      Type Parameters:
      U - Type of transformation result
      Parameters:
      f - A transformation
      Returns:
      An instance of type U
      Throws:
      NullPointerException - if f is null
    • toJavaSet

      public TreeSet<T> toJavaSet()
      Description copied from interface: Set
      Converts this Vavr Set to a java.util.Set while preserving characteristics like insertion order (LinkedHashSet) and sort order (SortedSet).
      Specified by:
      toJavaSet in interface Set<T>
      Specified by:
      toJavaSet in interface SortedSet<T>
      Specified by:
      toJavaSet in interface Value<T>
      Returns:
      a new java.util.Set instance
    • union

      public TreeSet<T> union(Set<? extends T> elements)
      Description copied from interface: Set
      Adds all of the elements of that set to this set, if not already present.

      See also Set.addAll(Iterable).

      Specified by:
      union in interface Set<T>
      Specified by:
      union in interface SortedSet<T>
      Parameters:
      elements - The set to form the union with.
      Returns:
      A new set that contains all distinct elements of this and that set.
    • unzip

      public <T1, T2> Tuple2<TreeSet<T1>,TreeSet<T2>> unzip(Function<? super T,Tuple2<? extends T1,? extends T2>> unzipper)
      Description copied from interface: Traversable
      Unzips this elements by mapping this elements to pairs which are subsequently split into two distinct sets.
      Specified by:
      unzip in interface Set<T>
      Specified by:
      unzip in interface SortedSet<T>
      Specified by:
      unzip in interface Traversable<T>
      Type Parameters:
      T1 - 1st element type of a pair returned by unzipper
      T2 - 2nd element type of a pair returned by unzipper
      Parameters:
      unzipper - a function which converts elements of this to pairs
      Returns:
      A pair of set containing elements split by unzipper
    • unzip3

      public <T1, T2, T3> Tuple3<TreeSet<T1>,TreeSet<T2>,TreeSet<T3>> unzip3(Function<? super T,Tuple3<? extends T1,? extends T2,? extends T3>> unzipper)
      Description copied from interface: Traversable
      Unzips this elements by mapping this elements to triples which are subsequently split into three distinct sets.
      Specified by:
      unzip3 in interface Set<T>
      Specified by:
      unzip3 in interface SortedSet<T>
      Specified by:
      unzip3 in interface Traversable<T>
      Type Parameters:
      T1 - 1st element type of a triplet returned by unzipper
      T2 - 2nd element type of a triplet returned by unzipper
      T3 - 3rd element type of a triplet returned by unzipper
      Parameters:
      unzipper - a function which converts elements of this to pairs
      Returns:
      A triplet of set containing elements split by unzipper
    • zip

      public <U> TreeSet<Tuple2<T,U>> zip(Iterable<? extends U> that)
      Description copied from interface: Traversable
      Returns a traversable formed from this traversable and another Iterable collection by combining corresponding elements in pairs. If one of the two iterables is longer than the other, its remaining elements are ignored.

      The length of the returned traversable is the minimum of the lengths of this traversable and that iterable.

      Specified by:
      zip in interface Set<T>
      Specified by:
      zip in interface SortedSet<T>
      Specified by:
      zip in interface Traversable<T>
      Type Parameters:
      U - The type of the second half of the returned pairs.
      Parameters:
      that - The Iterable providing the second half of each result pair.
      Returns:
      a new traversable containing pairs consisting of corresponding elements of this traversable and that iterable.
    • zipWith

      public <U, R> TreeSet<R> zipWith(Iterable<? extends U> that, BiFunction<? super T,? super U,? extends R> mapper)
      Description copied from interface: Traversable
      Returns a traversable formed from this traversable and another Iterable collection by mapping elements. If one of the two iterables is longer than the other, its remaining elements are ignored.

      The length of the returned traversable is the minimum of the lengths of this traversable and that iterable.

      Specified by:
      zipWith in interface Set<T>
      Specified by:
      zipWith in interface SortedSet<T>
      Specified by:
      zipWith in interface Traversable<T>
      Type Parameters:
      U - The type of the second parameter of the mapper.
      R - The type of the mapped elements.
      Parameters:
      that - The Iterable providing the second parameter of the mapper.
      mapper - a mapper.
      Returns:
      a new traversable containing mapped elements of this traversable and that iterable.
    • zipAll

      public <U> TreeSet<Tuple2<T,U>> zipAll(Iterable<? extends U> that, T thisElem, U thatElem)
      Description copied from interface: Traversable
      Returns a traversable formed from this traversable and another Iterable by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

      The length of the returned traversable is the maximum of the lengths of this traversable and that iterable.

      Special case: if this traversable is shorter than that elements, and that elements contains duplicates, the resulting traversable may be shorter than the maximum of the lengths of this and that because a traversable contains an element at most once.

      If this Traversable is shorter than that, thisElem values are used to fill the result. If that is shorter than this Traversable, thatElem values are used to fill the result.

      Specified by:
      zipAll in interface Set<T>
      Specified by:
      zipAll in interface SortedSet<T>
      Specified by:
      zipAll in interface Traversable<T>
      Type Parameters:
      U - The type of the second half of the returned pairs.
      Parameters:
      that - The Iterable providing the second half of each result pair.
      thisElem - The element to be used to fill up the result if this traversable is shorter than that.
      thatElem - The element to be used to fill up the result if that is shorter than this traversable.
      Returns:
      A new traversable containing pairs consisting of corresponding elements of this traversable and that.
    • zipWithIndex

      public TreeSet<Tuple2<T,Integer>> zipWithIndex()
      Description copied from interface: Traversable
      Zips this traversable with its indices.
      Specified by:
      zipWithIndex in interface Set<T>
      Specified by:
      zipWithIndex in interface SortedSet<T>
      Specified by:
      zipWithIndex in interface Traversable<T>
      Returns:
      A new traversable containing all elements of this traversable paired with their index, starting with 0.
    • zipWithIndex

      public <U> SortedSet<U> zipWithIndex(BiFunction<? super T,? super Integer,? extends U> mapper)
      Description copied from interface: Traversable
      Zips this traversable with its indices by applying mapper provided.
      Specified by:
      zipWithIndex in interface Set<T>
      Specified by:
      zipWithIndex in interface SortedSet<T>
      Specified by:
      zipWithIndex in interface Traversable<T>
      Type Parameters:
      U - The type of the mapped elements.
      Parameters:
      mapper - a mapper.
      Returns:
      a new traversable containing elements of this traversable, zipped with indices, and mapped with mapper provided.
    • equals

      public boolean equals(Object o)
      Description copied from interface: Traversable
      In Vavr there are four basic classes of collections:
      • Seq (sequential elements)
      • Set (distinct elements)
      • Map (indexed elements)
      • Multimap (indexed collections)
      Two collection instances of these classes are equal if and only if both collections
      • belong to the same basic collection class (Seq, Set, Map or Multimap)
      • contain the same elements
      • have the same element order, if the collections are of type Seq
      Two Map/Multimap elements, resp. entries, (key1, value1) and (key2, value2) are equal, if the keys are equal and the values are equal.

      Notes:

      • No collection instance equals null, e.g. Queue(1) not equals null.
      • Nulls are allowed and handled as expected, e.g. List(null, 1) equals Stream(null, 1) and HashMap((null, 1)) equals LinkedHashMap((null, 1)).
      • The element order is taken into account for Seq only. E.g. List(null, 1) not equals Stream(1, null) and HashMap((null, 1), ("a", null)) equals LinkedHashMap(("a", null), (null, 1)). The reason is, that we do not know which implementations we compare when having two instances of type Map, Multimap or Set (see Liskov Substitution Principle).
      • Other collection classes are equal if their types are equal and their elements are equal (in iteration order).
      • Iterator equality is defined to be object reference equality.
      Specified by:
      equals in interface Traversable<T>
      Specified by:
      equals in interface Value<T>
      Overrides:
      equals in class Object
      Parameters:
      o - an object, may be null
      Returns:
      true, if this collection equals the given object according to the rules described above, false otherwise.
    • hashCode

      public int hashCode()
      Description copied from interface: Traversable
      Returns the hash code of this collection.
      We distinguish between two types of hashes, those for collections with predictable iteration order (like Seq) and those with arbitrary iteration order (like Set, Map and Multimap).
      In all cases the hash of an empty collection is defined to be 1.
      Collections with predictable iteration order are hashed as follows:
      
       int hash = 1;
       for (T t : this) { hash = hash * 31 + Objects.hashCode(t); }
       
      Collections with arbitrary iteration order are hashed in a way such that the hash of a fixed number of elements is independent of their iteration order.
      
       int hash = 1;
       for (T t : this) { hash += Objects.hashCode(t); }
       
      Please note that the particular hashing algorithms may change in a future version of Vavr.
      Generally, hash codes of collections aren't cached in Vavr (opposed to the size/length). Storing hash codes in order to reduce the time complexity would increase the memory footprint. Persistent collections are built upon tree structures, it allows us to implement efficient memory sharing. A drawback of tree structures is that they make it necessary to store collection attributes at each tree node (read: element).
      The computation of the hash code is linear in time, i.e. O(n). If the hash code of a collection is re-calculated often, e.g. when using a List as HashMap key, we might want to cache the hash code. This can be achieved by simply using a wrapper class, which is not included in Vavr but could be implemented like this:
      public final class Hashed<K> {
      
           private final K key;
           private final Lazy<Integer> hashCode;
      
           public Hashed(K key) {
               this.key = key;
               this.hashCode = Lazy.of(() -> Objects.hashCode(key));
           }
      
           public K key() {
               return key;
           }
      
           &#64;Override
           public boolean equals(Object o) {
               if (o == key) {
                   return true;
               } else if (key != null && o instanceof Hashed) {
                   final Hashed that = (Hashed) o;
                   return key.equals(that.key);
               } else {
                   return false;
               }
           }
      
           &#64;Override
           public int hashCode() {
               return hashCode.get();
           }
      
           &#64;Override
           public String toString() {
               return "Hashed(" + (key == null ? "null" : key.toString()) + ")";
           }
       }
      Specified by:
      hashCode in interface Traversable<T>
      Specified by:
      hashCode in interface Value<T>
      Overrides:
      hashCode in class Object
      Returns:
      The hash code of this collection
    • stringPrefix

      public String stringPrefix()
      Description copied from interface: Value
      Returns the name of this Value type, which is used by toString().
      Specified by:
      stringPrefix in interface Value<T>
      Returns:
      This type name.
    • toString

      public String toString()
      Description copied from interface: Value
      Clarifies that values have a proper toString() method implemented.

      See Object.toString().

      Specified by:
      toString in interface Value<T>
      Overrides:
      toString in class Object
      Returns:
      A String representation of this object