Package myAdapter

Interface HSet

All Superinterfaces:
HCollection
public interface HSet extends HCollection
A collection that contains no duplicate elements. More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2), and at most one null element. As implied by its name, this interface models the mathematical set abstraction.

The Set interface places additional stipulations, beyond those inherited from the Collection interface, on the contracts of all constructors and on the contracts of the add, equals and hashCode methods. Declarations for other inherited methods are also included here for convenience.

The additional stipulation on constructors is, not surprisingly, that all constructors must create a set that contains no duplicate elements (as defined above).

Some set implementations have restrictions on the elements that they may contain. For example, some implementations prohibit null elements, and some have restrictions on the types of their elements. Attempting to add an ineligible element throws an unchecked exception, typically NullPointerException or ClassCastException. Attempting to query the presence of an ineligible element may throw an exception, or it may simply return false; some implementations will exhibit the former behavior and some will exhibit the latter. More generally, attempting an operation on an ineligible element whose completion would not result in the insertion of an ineligible element into the set may throw an exception or it may succeed, at the option of the implementation. Such exceptions are marked as "optional" in the specification for this interface.

See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    add(Object e)
    Adds the specified element to this set if it is not already present (optional operation).
    boolean
    addAll(HCollection coll)
    Adds all of the elements in the specified collection to this set if they're not already present (optional operation).
    void
    clear()
    Removes all of the elements from this set (optional operation).
    boolean
    contains(Object o)
    Returns true if this set contains the specified element.
    boolean
    containsAll(HCollection coll)
    Returns true if this set contains all of the elements of the specified collection.
    boolean
    equals(Object o)
    Compares the specified object with this set for equality.
    int
    hashCode()
    Returns the hash code value for this set.
    boolean
    isEmpty()
    Returns true if this set contains no elements.
    HIterator
    iterator()
    Returns an iterator over the elements in this set.
    boolean
    remove(Object o)
    Removes the specified element from this set if it is present (optional operation).
    boolean
    removeAll(HCollection coll)
    Removes from this set all of its elements that are contained in the specified collection (optional operation).
    boolean
    retainAll(HCollection coll)
    Retains only the elements in this set that are contained in the specified collection (optional operation).
    int
    size()
    Returns the number of elements in this set (its cardinality).
    Object[]
    toArray()
    Returns an array containing all of the elements in this set.
    Object[]
    toArray(Object[] arrayTarget)
    Returns an array containing all of the elements in this set; the runtime type of the returned array is that of the specified array.

  • Method Details

    • size

      int size()
      Returns the number of elements in this set (its cardinality). If this set contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
      Specified by:
      size in interface HCollection
      Returns:
      the number of elements in this set (its cardinality)

    • isEmpty

      boolean isEmpty()
      Returns true if this set contains no elements.
      Specified by:
      isEmpty in interface HCollection
      Returns:
      true if this set contains no elements

    • contains

      boolean contains(Object o)
      Returns true if this set contains the specified element. More formally, returns true if and only if this set contains an element e such that Objects.equals(o, e).
      Specified by:
      contains in interface HCollection
      Parameters:
      o - element whose presence in this set is to be tested
      Returns:
      true if this set contains the specified element
      Throws:
      NullPointerException - if the specified element is null.

    • iterator

      HIterator iterator()
      Returns an iterator over the elements in this set. The elements are returned in no particular order (unless this set is an instance of some class that provides a guarantee).
      Specified by:
      iterator in interface HCollection
      Returns:
      an iterator over the elements in this set

    • toArray

      Object[] toArray()
      Returns an array containing all of the elements in this set. If this set makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.

      The returned array will be "safe" in that no references to it are maintained by this set. (In other words, this method must allocate a new array even if this set is backed by an array). The caller is thus free to modify the returned array.

      This method acts as bridge between array-based and collection-based APIs.

      Specified by:
      toArray in interface HCollection
      Returns:
      an array containing all the elements in this set

    • toArray

      Object[] toArray(Object[] arrayTarget)
      Returns an array containing all of the elements in this set; the runtime type of the returned array is that of the specified array. If the set fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this set.

      If this set fits in the specified array with room to spare (i.e., the array has more elements than this set), the element in the array immediately following the end of the set is set to null. (This is useful in determining the length of this set only if the caller knows that this set does not contain any null elements.)

      If this set makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.

      Like the toArray() method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.

      Suppose x is a set known to contain only strings. The following code can be used to dump the set into a newly allocated array of String: 

           String[] y = x.toArray(new String[0]);
      Note that toArray(new Object[0]) is identical in function to toArray().
      Specified by:
      toArray in interface HCollection
      Parameters:
      arrayTarget - the array into which the elements of this set 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 containing all the elements in this set
      Throws:
      NullPointerException - if the specified array is null

    • add

      boolean add(Object e)
      Adds the specified element to this set if it is not already present (optional operation). More formally, adds the specified element e to this set if the set contains no element e2 such that Objects.equals(e, e2). If this set already contains the element, the call leaves the set unchanged and returns false. In combination with the restriction on constructors, this ensures that sets never contain duplicate elements.

      The stipulation above does not imply that sets must accept all elements; sets may refuse to add any particular element, including null, and throw an exception, as described in the specification for

      invalid @link 
      Collection.add
      . Individual set implementations should clearly document any restrictions on the elements that they may contain.
      Specified by:
      add in interface HCollection
      Parameters:
      e - element to be added to this set
      Returns:
      true if this set did not already contain the specified element
      Throws:
      UnsupportedOperationException - if the add operation is not supported by this set
      NullPointerException - if the specified element is null and this set does not permit null elements

    • remove

      boolean remove(Object o)
      Removes the specified element from this set if it is present (optional operation). More formally, removes an element e such that Objects.equals(o, e), if this set contains such an element. Returns true if this set contained the element (or equivalently, if this set changed as a result of the call). (This set will not contain the element once the call returns.)
      Specified by:
      remove in interface HCollection
      Parameters:
      o - object to be removed from this set, if present
      Returns:
      true if this set contained the specified element
      Throws:
      NullPointerException - if the specified element is null and this set does not permit null elements

    • containsAll

      boolean containsAll(HCollection coll)
      Returns true if this set contains all of the elements of the specified collection. If the specified collection is also a set, this method returns true if it is a subset of this set.
      Specified by:
      containsAll in interface HCollection
      Parameters:
      coll - collection to be checked for containment in this set
      Returns:
      true if this set contains all of the elements of the specified collection
      Throws:
      NullPointerException - if the specified collection contains one or more null elements and this set does not permit null elements or if the specified collection is null
      See Also:

    • addAll

      boolean addAll(HCollection coll)
      Adds all of the elements in the specified collection to this set if they're not already present (optional operation). If the specified collection is also a set, the addAll operation effectively modifies this set so that its value is the union of the two sets. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress.
      Specified by:
      addAll in interface HCollection
      Parameters:
      coll - collection containing elements to be added to this set
      Returns:
      true if this set changed as a result of the call
      Throws:
      UnsupportedOperationException - if the addAll operation is not supported by this set
      NullPointerException - if the specified collection contains one or more null elements and this set does not permit null elements, or if the specified collection is null
      See Also:

    • retainAll

      boolean retainAll(HCollection coll)
      Retains only the elements in this set that are contained in the specified collection (optional operation). In other words, removes from this set all of its elements that are not contained in the specified collection. If the specified collection is also a set, this operation effectively modifies this set so that its value is the intersection of the two sets.
      Specified by:
      retainAll in interface HCollection
      Parameters:
      coll - collection containing elements to be retained in this set
      Returns:
      true if this set changed as a result of the call
      Throws:
      NullPointerException - if this set contains a null element and the specified collection does not permit null elements or if the specified collection is null
      See Also:

    • removeAll

      boolean removeAll(HCollection coll)
      Removes from this set all of its elements that are contained in the specified collection (optional operation). If the specified collection is also a set, this operation effectively modifies this set so that its value is the asymmetric set difference of the two sets.
      Specified by:
      removeAll in interface HCollection
      Parameters:
      coll - collection containing elements to be removed from this set
      Returns:
      true if this set changed as a result of the call
      Throws:
      NullPointerException - if this set contains a null element or if the specified collection is null
      See Also:

    • clear

      void clear()
      Removes all of the elements from this set (optional operation). The set will be empty after this call returns.
      Specified by:
      clear in interface HCollection
      Throws:
      UnsupportedOperationException - if the clear method is not supported by this set

    • equals

      boolean equals(Object o)
      Compares the specified object with this set for equality. Returns true if the specified object is also a set, the two sets have the same size, and every member of the specified set is contained in this set (or equivalently, every member of this set is contained in the specified set). This definition ensures that the equals method works properly across different implementations of the set interface.
      Specified by:
      equals in interface HCollection
      Overrides:
      equals in class Object
      Parameters:
      o - object to be compared for equality with this set
      Returns:
      true if the specified object is equal to this set
      See Also:

    • hashCode

      int hashCode()
      Returns the hash code value for this set. The hash code of a set is defined to be the sum of the hash codes of the elements in the set, where the hash code of a null element is defined to be zero. This ensures that s1.equals(s2) implies that s1.hashCode()==s2.hashCode() for any two sets s1 and s2, as required by the general contract of Object.hashCode().
      Specified by:
      hashCode in interface HCollection
      Overrides:
      hashCode in class Object
      Returns:
      the hash code value for this set
      See Also: