Class WeakList<E>

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>, java.util.List<E>

    public class WeakList<E>
    extends java.lang.Object
    implements java.util.List<E>, java.io.Serializable
    A list with weak entries.
    See Also:
    Serialized Form
    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected java.lang.ref.Reference<E>[] array
      The list of elements.
      protected java.lang.ref.ReferenceQueue queue
      Reference queue for garbage-collected elements.
      protected java.util.List<E> serialized_list  
      protected int size
      The number of elements.
      protected int state
      The state (to check for modifications).
    • Constructor Summary

      Constructors 
      Constructor Description
      WeakList()
      Create a new list.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void add​(int index, java.lang.Object o)
      Inserts the specified element at the specified position in this list (optional operation).
      boolean add​(E o)
      Appends the specified element to the end of this list (optional operation).
      boolean addAll​(int index, java.util.Collection collection)
      Inserts all of the elements in the specified collection into this list at the specified position (optional operation).
      boolean addAll​(java.util.Collection collection)
      Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's iterator (optional operation).
      protected static void checkForEmptySlots​(java.util.List list)
      Check for empty slots in list.
      void clear()
      Removes all of the elements from this list (optional operation).
      boolean contains​(java.lang.Object o)
      Returns
      boolean containsAll​(java.util.Collection c)
      Returns
      protected static java.lang.String[] createTestvalues​(java.lang.String teststring, int size)
      Create some string values for testing.
      E get​(int index)
      Returns the element at the specified position in this list.
      int indexOf​(java.lang.Object o)
      Returns the index in this list of the first occurrence of the specified element, or -1 if this list does not contain this element.
      boolean isEmpty()
      Returns
      java.util.Iterator<E> iterator()
      Returns an iterator over the elements in this list in proper sequence.
      int lastIndexOf​(java.lang.Object o)
      Returns the index in this list of the last occurrence of the specified element, or -1 if this list does not contain this element.
      java.util.ListIterator<E> listIterator()
      Returns a list iterator of the elements in this list (in proper sequence).
      java.util.ListIterator<E> listIterator​(int index)
      Returns a list iterator of the elements in this list (in proper sequence), starting at the specified position in this list.
      static void main​(java.lang.String[] args)
      Main method for testing.
      protected java.lang.Object readResolve()
      Perform special handling on deserialization.
      E remove​(int index)
      Removes the element at the specified position in this list (optional operation).
      boolean remove​(java.lang.Object o)
      Removes the first occurrence in this list of the specified element (optional operation).
      boolean removeAll​(java.util.Collection c)
      Removes from this list all the elements that are contained in the specified collection (optional operation).
      boolean retainAll​(java.util.Collection c)
      Retains only the elements in this list that are contained in the specified collection (optional operation).
      java.lang.Object set​(int index, java.lang.Object o)
      Replaces the element at the specified position in this list with the specified element (optional operation).
      int size()
      Returns the number of elements in this list.
      java.util.List<E> subList​(int fromIndex, int toIndex)
      Returns a view of the portion of this list between the specified
      java.lang.Object[] toArray()
      Returns an array containing all of the elements in this list in proper sequence.
      java.lang.Object[] toArray​(java.lang.Object[] ret)
      Returns an array containing all of the elements in this list in proper sequence; the runtime type of the returned array is that of the specified array.
      java.lang.String toString()
      Get the string representation.
      protected java.lang.Object writeReplace()
      Perform special handling on serialization.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
      • Methods inherited from interface java.util.Collection

        parallelStream, removeIf, stream, toArray
      • Methods inherited from interface java.lang.Iterable

        forEach
      • Methods inherited from interface java.util.List

        equals, hashCode, replaceAll, sort, spliterator
    • Field Detail

      • array

        protected transient java.lang.ref.Reference<E>[] array
        The list of elements.
      • size

        protected int size
        The number of elements.
      • state

        protected int state
        The state (to check for modifications).
      • queue

        protected transient java.lang.ref.ReferenceQueue queue
        Reference queue for garbage-collected elements.
      • serialized_list

        protected java.util.List<E> serialized_list
    • Constructor Detail

      • WeakList

        public WeakList()
        Create a new list.
    • Method Detail

      • size

        public int size()
        Returns the number of elements in this list. If this list contains more than
        Specified by:
        size in interface java.util.Collection<E>
        Specified by:
        size in interface java.util.List<E>
        Returns:
        the number of elements in this list.
      • isEmpty

        public boolean isEmpty()
        Returns
        Specified by:
        isEmpty in interface java.util.Collection<E>
        Specified by:
        isEmpty in interface java.util.List<E>
        Returns:
      • contains

        public boolean contains​(java.lang.Object o)
        Returns
        Specified by:
        contains in interface java.util.Collection<E>
        Specified by:
        contains in interface java.util.List<E>
        Parameters:
        o - element whose presence in this list is to be tested.
        Returns:
        Throws:
        java.lang.ClassCastException - if the type of the specified element is incompatible with this list (optional).
        java.lang.NullPointerException - if the specified element is null.
      • iterator

        public java.util.Iterator<E> iterator()
        Returns an iterator over the elements in this list in proper sequence. Can handle garbage collection of elements, but fails fast in the presence of concurrent modifications.
        Specified by:
        iterator in interface java.util.Collection<E>
        Specified by:
        iterator in interface java.lang.Iterable<E>
        Specified by:
        iterator in interface java.util.List<E>
        Returns:
        an iterator over the elements in this list in proper sequence.
      • toArray

        public java.lang.Object[] toArray()
        Returns an array containing all of the elements in this list in proper sequence. Obeys the general contract of the
        Specified by:
        toArray in interface java.util.Collection<E>
        Specified by:
        toArray in interface java.util.List<E>
        Returns:
        an array containing all of the elements in this list in proper sequence.
        See Also:
        Arrays.asList(Object[])
      • toArray

        public java.lang.Object[] toArray​(java.lang.Object[] ret)
        Returns an array containing all of the elements in this list in proper sequence; the runtime type of the returned array is that of the specified array. Obeys the general contract of the
        Specified by:
        toArray in interface java.util.Collection<E>
        Specified by:
        toArray in interface java.util.List<E>
        Parameters:
        ret - the array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
        Returns:
        an array containing the elements of this list.
        Throws:
        java.lang.ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this list.
        java.lang.NullPointerException - if the specified array is
      • add

        public boolean add​(E o)
        Appends the specified element to the end of this list (optional operation).
        Specified by:
        add in interface java.util.Collection<E>
        Specified by:
        add in interface java.util.List<E>
        Parameters:
        o - element to be appended to this list.
        Returns:
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.ClassCastException - if the class of the specified element prevents it from being added to this list.
        java.lang.NullPointerException - if the specified element is nul.
        java.lang.IllegalArgumentException - if some aspect of this element prevents it from being added to this list.
      • remove

        public boolean remove​(java.lang.Object o)
        Removes the first occurrence in this list of the specified element (optional operation). If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest index i such that
        Specified by:
        remove in interface java.util.Collection<E>
        Specified by:
        remove in interface java.util.List<E>
        Parameters:
        o - element to be removed from this list, if present.
        Returns:
        Throws:
        java.lang.ClassCastException - if the type of the specified element is incompatible with this list (optional).
        java.lang.NullPointerException - if the specified element is null.
        java.lang.UnsupportedOperationException - if the
      • containsAll

        public boolean containsAll​(java.util.Collection c)
        Returns
        Specified by:
        containsAll in interface java.util.Collection<E>
        Specified by:
        containsAll in interface java.util.List<E>
        Parameters:
        c - collection to be checked for containment in this list.
        Returns:
        Throws:
        java.lang.ClassCastException - if the types of one or more elements in the specified collection are incompatible with this list (optional).
        java.lang.NullPointerException - if the specified collection contains one or more null elements and this list does not support null elements (optional).
        java.lang.NullPointerException - if the specified collection is
        See Also:
        contains(Object)
      • addAll

        public boolean addAll​(java.util.Collection collection)
        Appends all of the elements in the specified collection to the end of this list, in the order that they are returned by the specified collection's iterator (optional operation). The behavior of this operation is unspecified if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)
        Specified by:
        addAll in interface java.util.Collection<E>
        Specified by:
        addAll in interface java.util.List<E>
        Parameters:
        collection - collection whose elements are to be added to this list.
        Returns:
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.ClassCastException - if the class of an element in the specified collection prevents it from being added to this list.
        java.lang.NullPointerException - if the specified collection contains one or more null elements and this list does not support null elements, or if the specified collection is
        java.lang.IllegalArgumentException - if some aspect of an element in the specified collection prevents it from being added to this list.
        See Also:
        add(Object)
      • addAll

        public boolean addAll​(int index,
                              java.util.Collection collection)
        Inserts all of the elements in the specified collection into this list at the specified position (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in this list in the order that they are returned by the specified collection's iterator. The behavior of this operation is unspecified if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)
        Specified by:
        addAll in interface java.util.List<E>
        Parameters:
        index - index at which to insert first element from the specified collection.
        collection - elements to be inserted into this list.
        Returns:
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.ClassCastException - if the class of one of elements of the specified collection prevents it from being added to this list.
        java.lang.NullPointerException - if the specified collection contains one or more null elements and this list does not support null elements, or if the specified collection is
        java.lang.IllegalArgumentException - if some aspect of one of elements of the specified collection prevents it from being added to this list.
        java.lang.IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size()).
      • removeAll

        public boolean removeAll​(java.util.Collection c)
        Removes from this list all the elements that are contained in the specified collection (optional operation).
        Specified by:
        removeAll in interface java.util.Collection<E>
        Specified by:
        removeAll in interface java.util.List<E>
        Parameters:
        c - collection that defines which elements will be removed from this list.
        Returns:
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.ClassCastException - if the types of one or more elements in this list are incompatible with the specified collection (optional).
        java.lang.NullPointerException - if this list contains one or more null elements and the specified collection does not support null elements (optional).
        java.lang.NullPointerException - if the specified collection is
        See Also:
        remove(Object), contains(Object)
      • retainAll

        public boolean retainAll​(java.util.Collection c)
        Retains only the elements in this list that are contained in the specified collection (optional operation). In other words, removes from this list all the elements that are not contained in the specified collection.
        Specified by:
        retainAll in interface java.util.Collection<E>
        Specified by:
        retainAll in interface java.util.List<E>
        Parameters:
        c - collection that defines which elements this set will retain.
        Returns:
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.ClassCastException - if the types of one or more elements in this list are incompatible with the specified collection (optional).
        java.lang.NullPointerException - if this list contains one or more null elements and the specified collection does not support null elements (optional).
        java.lang.NullPointerException - if the specified collection is
        See Also:
        remove(Object), contains(Object)
      • clear

        public void clear()
        Removes all of the elements from this list (optional operation). This list will be empty after this call returns (unless it throws an exception).
        Specified by:
        clear in interface java.util.Collection<E>
        Specified by:
        clear in interface java.util.List<E>
      • get

        public E get​(int index)
        Returns the element at the specified position in this list.
        Specified by:
        get in interface java.util.List<E>
        Parameters:
        index - index of element to return.
        Returns:
        the element at the specified position in this list.
        Throws:
        java.lang.IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size()).
      • set

        public java.lang.Object set​(int index,
                                    java.lang.Object o)
        Replaces the element at the specified position in this list with the specified element (optional operation).
        Specified by:
        set in interface java.util.List<E>
        Parameters:
        index - index of element to replace.
        o - element to be stored at the specified position.
        Returns:
        the element previously at the specified position.
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.ClassCastException - if the class of the specified element prevents it from being added to this list.
        java.lang.NullPointerException - if the specified element is null and this list does not support null elements.
        java.lang.IllegalArgumentException - if some aspect of the specified element prevents it from being added to this list.
        java.lang.IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size()).
      • add

        public void add​(int index,
                        java.lang.Object o)
        Inserts the specified element at the specified position in this list (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).
        Specified by:
        add in interface java.util.List<E>
        Parameters:
        index - index at which the specified element is to be inserted.
        o - element to be inserted.
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.ClassCastException - if the class of the specified element prevents it from being added to this list.
        java.lang.NullPointerException - if the specified element is null and this list does not support null elements.
        java.lang.IllegalArgumentException - if some aspect of the specified element prevents it from being added to this list.
        java.lang.IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size()).
      • remove

        public E remove​(int index)
        Removes the element at the specified position in this list (optional operation). Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.
        Specified by:
        remove in interface java.util.List<E>
        Parameters:
        index - the index of the element to removed.
        Returns:
        the element previously at the specified position.
        Throws:
        java.lang.UnsupportedOperationException - if the
        java.lang.IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size()).
      • indexOf

        public int indexOf​(java.lang.Object o)
        Returns the index in this list of the first occurrence of the specified element, or -1 if this list does not contain this element. More formally, returns the lowest index
        Specified by:
        indexOf in interface java.util.List<E>
        Parameters:
        o - element to search for.
        Returns:
        the index in this list of the first occurrence of the specified element, or -1 if this list does not contain this element.
        Throws:
        java.lang.ClassCastException - if the type of the specified element is incompatible with this list (optional).
        java.lang.NullPointerException - if the specified element is null.
      • lastIndexOf

        public int lastIndexOf​(java.lang.Object o)
        Returns the index in this list of the last occurrence of the specified element, or -1 if this list does not contain this element. More formally, returns the highest index
        Specified by:
        lastIndexOf in interface java.util.List<E>
        Parameters:
        o - element to search for.
        Returns:
        the index in this list of the last occurrence of the specified element, or -1 if this list does not contain this element.
        Throws:
        java.lang.ClassCastException - if the type of the specified element is incompatible with this list (optional).
        java.lang.NullPointerException - if the specified element is null.
      • listIterator

        public java.util.ListIterator<E> listIterator()
        Returns a list iterator of the elements in this list (in proper sequence).
        Specified by:
        listIterator in interface java.util.List<E>
        Returns:
        a list iterator of the elements in this list (in proper sequence).
      • listIterator

        public java.util.ListIterator<E> listIterator​(int index)
        Returns a list iterator of the elements in this list (in proper sequence), starting at the specified position in this list. The specified index indicates the first element that would be returned by an initial call to the
        Specified by:
        listIterator in interface java.util.List<E>
        Parameters:
        index - index of first element to be returned from the list iterator (by a call to the
        Returns:
        a list iterator of the elements in this list (in proper sequence), starting at the specified position in this list.
        Throws:
        java.lang.IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size()).
      • subList

        public java.util.List<E> subList​(int fromIndex,
                                         int toIndex)
        Returns a view of the portion of this list between the specified
        Specified by:
        subList in interface java.util.List<E>
        Parameters:
        fromIndex - low endpoint (inclusive) of the subList.
        toIndex - high endpoint (exclusive) of the subList.
        Returns:
        a view of the specified range within this list.
        Throws:
        java.lang.IndexOutOfBoundsException - for an illegal endpoint index value (fromIndex < 0 || toIndex > size || fromIndex > toIndex).
      • toString

        public java.lang.String toString()
        Get the string representation.
        Overrides:
        toString in class java.lang.Object
      • writeReplace

        protected java.lang.Object writeReplace()
                                         throws java.io.ObjectStreamException
        Perform special handling on serialization.
        Throws:
        java.io.ObjectStreamException
      • readResolve

        protected java.lang.Object readResolve()
                                        throws java.io.ObjectStreamException
        Perform special handling on deserialization.
        Throws:
        java.io.ObjectStreamException
      • main

        public static void main​(java.lang.String[] args)
        Main method for testing.
      • createTestvalues

        protected static java.lang.String[] createTestvalues​(java.lang.String teststring,
                                                             int size)
        Create some string values for testing.
      • checkForEmptySlots

        protected static void checkForEmptySlots​(java.util.List list)
        Check for empty slots in list.