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Oracle® Coherence Java API Reference
v3.5.1

E15583-01


com.tangosol.util
Class CircularArrayList

java.lang.Object
  extended by java.util.AbstractCollection
      extended by java.util.AbstractList
          extended by com.tangosol.util.CircularArrayList

All Implemented Interfaces:
java.io.Serializable, java.lang.Cloneable, java.lang.Iterable, java.util.Collection, java.util.List, java.util.RandomAccess

public class CircularArrayList
extends java.util.AbstractList
implements java.util.List, java.util.RandomAccess, java.lang.Cloneable, java.io.Serializable

Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. (This class is roughly equivalent to ArrayList, except that it is optimized for removing elements at the front and back of the list to facilitate use as a queue or deque.

The size, isEmpty, get, set, iterator, and listIterator operations run in constant time. The add operation runs in amortized constant time, that is, adding n elements requires O(n) time. All of the other operations run in linear time (roughly speaking). The constant factor is low compared to that for the LinkedList implementation.

Each CircularArrayList instance has a capacity. The capacity is the size of the array used to store the elements in the list. It is always at least as large as the list size. As elements are added to an CircularArrayList, its capacity grows automatically. The details of the growth policy are not specified beyond the fact that adding an element has constant amortized time cost.

An application can increase the capacity of an CircularArrayList instance before adding a large number of elements using the ensureCapacity operation. This may reduce the amount of incremental reallocation.

Note that this implementation is not synchronized. If multiple threads access a CircularArrayList concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements, or explicitly resizes the backing array; merely setting the value of an element is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the list. If no object exists, the list should be "wrapped" using the Collections.synchronizedList method. This is best done at creation time, to prevent accidental unsynchronized access to the list:

        List list = Collections.synchronizedList(new CircularArrayList(...));
 

The iterators returned by this class's iterator and listIterator methods are fail-fast: if list is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.

Since:
Coherence 3.5
Author:
djl 2008.10.22

Field Summary
protected  java.lang.Object[] m_aoData
          The array into which the elements of the list are stored.
protected  int m_cElements
          The size of the list (the number of elements it contains).
protected  int m_iFirst
          The offset to the first element.
protected  int m_iLast
          The offset to one past the last element.

 

Fields inherited from class java.util.AbstractList
modCount

 

Constructor Summary
CircularArrayList()
          Create a new CircularArrayList with default settings.
CircularArrayList(java.util.Collection c)
          Construct a CircularArrayList containing the elements of the specified collection in the order they are returned by the collection's iterator.
CircularArrayList(int cInitialElements)
          Create a new CircularArrayList with the specified initial capacity.

 

Method Summary
 void add(int index, java.lang.Object o)
          Insert the element at the specified position in this list.
 boolean add(java.lang.Object o)
          
 boolean addAll(java.util.Collection c)
          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.
 boolean addAll(int index, java.util.Collection c)
          Inserts all of the elements in the specified Collection into this list, starting at the specified position.
 void clear()
          
 java.lang.Object clone()
          Returns a shallow copy of this list instance.
 boolean contains(java.lang.Object o)
          
 void dump()
          Outputs information to standard output about representation for debugging purposes.
protected  int effectiveIndex(int index)
          Calculate the effective index taking into account offsets and the circular nature of CircularArrayList.
 boolean ensureCapacity(int cMin)
          Increase the capacity of this list instance, if necessary, to ensure that it can hold at least the specified number of elements.
protected  boolean ensureCompactness()
          Ensure the representation of this list is appropriatly compact by shrinking if necessary.
protected  int ensureEffectiveIndex(int index)
          After range checking Calculate the effective index while taking into account the offsets and the circular nature of the list.
 java.lang.Object get(int index)
          
 int indexOf(java.lang.Object o)
          Search for the first occurence of the given argument, testing for equality using the equals method.
 boolean isEmpty()
          
 int lastIndexOf(java.lang.Object o)
          Returns the index of the last occurrence of the specified object in this CycicArrayList.
protected  void rangeCheck(int index)
          Check if the given index is in range.
 java.lang.Object remove(int index)
          Removes the element at the specified position in this list.
protected  void removeRange(int fromIndex, int toIndex)
          Removes from this list all of the elements whose indexes are between fromIndex, inclusive and toIndex, exclusive.
 java.lang.Object set(int index, java.lang.Object o)
          
 int size()
          
 java.lang.Object[] toArray()
          
 java.lang.Object[] toArray(java.lang.Object[] ao)
          
 void trimToSize()
          Trim the capacity of this list instance to be as small as possible.

 

Methods inherited from class java.util.AbstractList
equals, hashCode, iterator, listIterator, listIterator, subList

 

Methods inherited from class java.util.AbstractCollection
containsAll, remove, removeAll, retainAll, toString

 

Methods inherited from interface java.util.List
containsAll, equals, hashCode, iterator, listIterator, listIterator, remove, removeAll, retainAll, subList

 

Field Detail

m_aoData

protected java.lang.Object[] m_aoData
The array into which the elements of the list are stored. The capacity of the list is the length of this array buffer.

m_iFirst

protected int m_iFirst
The offset to the first element.

m_iLast

protected int m_iLast
The offset to one past the last element.

m_cElements

protected int m_cElements
The size of the list (the number of elements it contains).

Constructor Detail

CircularArrayList

public CircularArrayList()
Create a new CircularArrayList with default settings.

CircularArrayList

public CircularArrayList(int cInitialElements)
Create a new CircularArrayList with the specified initial capacity.
Parameters:
cInitialElements - the initial capacity of the list
Throws:
java.lang.IllegalArgumentException - if the specified initial capacity is negative

CircularArrayList

public CircularArrayList(java.util.Collection c)
Construct a CircularArrayList containing the elements of the specified collection in the order they are returned by the collection's iterator.
Parameters:
c - the collection whose elements are to be placed into this list

Method Detail

trimToSize

public void trimToSize()
Trim the capacity of this list instance to be as small as possible.

ensureCapacity

public boolean ensureCapacity(int cMin)
Increase the capacity of this list instance, if necessary, to ensure that it can hold at least the specified number of elements.
Parameters:
cMin - the minimum allowable capacity
Returns:
true if the capacity was increased

size

public int size()
Specified by:
size in interface java.util.Collection
Specified by:
size in interface java.util.List
Specified by:
size in class java.util.AbstractCollection

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface java.util.Collection
Specified by:
isEmpty in interface java.util.List
Overrides:
isEmpty in class java.util.AbstractCollection

contains

public boolean contains(java.lang.Object o)
Specified by:
contains in interface java.util.Collection
Specified by:
contains in interface java.util.List
Overrides:
contains in class java.util.AbstractCollection

indexOf

public int indexOf(java.lang.Object o)
Search for the first occurence of the given argument, testing for equality using the equals method.
Specified by:
indexOf in interface java.util.List
Overrides:
indexOf in class java.util.AbstractList
Parameters:
o - the element to search for
Returns:
the index of the first occurrence of the argument in this list; returns -1 if the object is not found

lastIndexOf

public int lastIndexOf(java.lang.Object o)
Returns the index of the last occurrence of the specified object in this CycicArrayList.
Specified by:
lastIndexOf in interface java.util.List
Overrides:
lastIndexOf in class java.util.AbstractList
Parameters:
o - the element to search for
Returns:
the index of the last occurrence of the specified object in this list; returns -1 if the object is not found

toArray

public java.lang.Object[] toArray()
Specified by:
toArray in interface java.util.Collection
Specified by:
toArray in interface java.util.List
Overrides:
toArray in class java.util.AbstractCollection

toArray

public java.lang.Object[] toArray(java.lang.Object[] ao)
Specified by:
toArray in interface java.util.Collection
Specified by:
toArray in interface java.util.List
Overrides:
toArray in class java.util.AbstractCollection

get

public java.lang.Object get(int index)
Specified by:
get in interface java.util.List
Specified by:
get in class java.util.AbstractList

set

public java.lang.Object set(int index,
                            java.lang.Object o)
Specified by:
set in interface java.util.List
Overrides:
set in class java.util.AbstractList

add

public boolean add(java.lang.Object o)
Specified by:
add in interface java.util.Collection
Specified by:
add in interface java.util.List
Overrides:
add in class java.util.AbstractList

add

public void add(int index,
                java.lang.Object o)
Insert the element at the specified position in this list. 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
Overrides:
add in class java.util.AbstractList
Parameters:
index - the index at which the specified element will be inserted
o - the element to be inserted
Throws:
java.lang.IndexOutOfBoundsException - if index is out of range

remove

public java.lang.Object remove(int index)
Removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices).
Specified by:
remove in interface java.util.List
Overrides:
remove in class java.util.AbstractList
Parameters:
index - the index of the element to removed
Returns:
the element that was removed from the list
Throws:
java.lang.IndexOutOfBoundsException - if index out of range

clear

public void clear()
Specified by:
clear in interface java.util.Collection
Specified by:
clear in interface java.util.List
Overrides:
clear in class java.util.AbstractList

addAll

public boolean addAll(java.util.Collection c)
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. The behavior of this operation is undefined if the specified Collection is modified while the operation is in progress. (This implies that the behavior of this call is undefined if the specified Collection is this list, and this list is nonempty.)
Specified by:
addAll in interface java.util.Collection
Specified by:
addAll in interface java.util.List
Overrides:
addAll in class java.util.AbstractCollection
Parameters:
c - the elements to be inserted into this list
Returns:
true if this list changed as a result of the call
Throws:
java.lang.NullPointerException - if the specified collection is null.

addAll

public boolean addAll(int index,
                      java.util.Collection c)
Inserts all of the elements in the specified Collection into this list, starting at the specified position. Shift the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in the list in the order that they are returned by the specified Collection's iterator.
Specified by:
addAll in interface java.util.List
Overrides:
addAll in class java.util.AbstractList
Parameters:
index - the index at which to insert first element from the specified collection
c - the elements to be inserted into this list
Returns:
true if this list changed as a result of the call
Throws:
java.lang.IndexOutOfBoundsException - if index out of range
java.lang.NullPointerException - if the specified Collection is null

removeRange

protected void removeRange(int fromIndex,
                           int toIndex)
Removes from this list all of the elements whose indexes are between fromIndex, inclusive and toIndex, exclusive. Shifts any succeeding elements to the left (reduces their index). This call shortens the list by (toIndex - fromIndex) elements. (If toIndex==fromIndex, this operation has no effect.)
Overrides:
removeRange in class java.util.AbstractList
Parameters:
fromIndex - the index of first element to be removed
toIndex - the index after last element to be removed.

clone

public java.lang.Object clone()
Returns a shallow copy of this list instance. The elements themselves are not copied.
Returns:
a clone of this list instance

effectiveIndex

protected int effectiveIndex(int index)
Calculate the effective index taking into account offsets and the circular nature of CircularArrayList.
Parameters:
index - the index to transform
Returns:
the effective index in the physical storage array

rangeCheck

protected void rangeCheck(int index)
Check if the given index is in range. If not, throw an appropriate runtime exception.
Parameters:
index - the index to be checked for being between size() and 0 inclusive
Throws:
java.lang.IndexOutOfBoundsException

ensureEffectiveIndex

protected int ensureEffectiveIndex(int index)
After range checking Calculate the effective index while taking into account the offsets and the circular nature of the list.
Parameters:
index - the index to transform
Returns:
the effective index in the physical storage array
Throws:
java.lang.IndexOutOfBoundsException

ensureCompactness

protected boolean ensureCompactness()
Ensure the representation of this list is appropriatly compact by shrinking if necessary.
Returns:
true if an actual compaction happened; false otherwise

dump

public void dump()
Outputs information to standard output about representation for debugging purposes.

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Oracle® Coherence Java API Reference
v3.5.1

E15583-01


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