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/* |
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* %W% %E% |
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* |
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* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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*/ |
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|
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package java.util; |
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import java.util.*; // for javadoc (till 6280605 is fixed) |
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|
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/** |
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* Resizable-array implementation of the <tt>List</tt> interface. Implements |
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* all optional list operations, and permits all elements, including |
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* <tt>null</tt>. In addition to implementing the <tt>List</tt> interface, |
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* this class provides methods to manipulate the size of the array that is |
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* used internally to store the list. (This class is roughly equivalent to |
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* <tt>Vector</tt>, except that it is unsynchronized.)<p> |
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* |
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* The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>, |
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* <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant |
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* time. The <tt>add</tt> operation runs in <i>amortized constant time</i>, |
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* that is, adding n elements requires O(n) time. All of the other operations |
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* run in linear time (roughly speaking). The constant factor is low compared |
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* to that for the <tt>LinkedList</tt> implementation.<p> |
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* |
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* Each <tt>ArrayList</tt> instance has a <i>capacity</i>. The capacity is |
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* the size of the array used to store the elements in the list. It is always |
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* at least as large as the list size. As elements are added to an ArrayList, |
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* its capacity grows automatically. The details of the growth policy are not |
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* specified beyond the fact that adding an element has constant amortized |
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* time cost.<p> |
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* |
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* An application can increase the capacity of an <tt>ArrayList</tt> instance |
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* before adding a large number of elements using the <tt>ensureCapacity</tt> |
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* operation. This may reduce the amount of incremental reallocation. |
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* |
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* <p><strong>Note that this implementation is not synchronized.</strong> |
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* If multiple threads access an <tt>ArrayList</tt> instance concurrently, |
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* and at least one of the threads modifies the list structurally, it |
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* <i>must</i> be synchronized externally. (A structural modification is |
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* any operation that adds or deletes one or more elements, or explicitly |
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* resizes the backing array; merely setting the value of an element is not |
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* a structural modification.) This is typically accomplished by |
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* synchronizing on some object that naturally encapsulates the list. |
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* |
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* If no such object exists, the list should be "wrapped" using the |
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* {@link Collections#synchronizedList Collections.synchronizedList} |
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* method. This is best done at creation time, to prevent accidental |
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* unsynchronized access to the list:<pre> |
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* List list = Collections.synchronizedList(new ArrayList(...));</pre> |
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* |
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* <p>The iterators returned by this class's <tt>iterator</tt> and |
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* <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is |
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* structurally modified at any time after the iterator is created, in any way |
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* except through the iterator's own <tt>remove</tt> or <tt>add</tt> methods, |
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* the iterator will throw a {@link ConcurrentModificationException}. Thus, in |
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* the face of concurrent modification, the iterator fails quickly and cleanly, |
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* rather than risking arbitrary, non-deterministic behavior at an undetermined |
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* time in the future.<p> |
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* |
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* Note that the fail-fast behavior of an iterator cannot be guaranteed |
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* as it is, generally speaking, impossible to make any hard guarantees in the |
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* presence of unsynchronized concurrent modification. Fail-fast iterators |
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* throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
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* Therefore, it would be wrong to write a program that depended on this |
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* exception for its correctness: <i>the fail-fast behavior of iterators |
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* should be used only to detect bugs.</i><p> |
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* |
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* This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @author Josh Bloch |
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* @author Neal Gafter |
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* @version %I%, %G% |
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* @see Collection |
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* @see List |
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* @see LinkedList |
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* @see Vector |
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* @since 1.2 |
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*/ |
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|
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public class ArrayList<E> extends AbstractList<E> |
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implements List<E>, RandomAccess, Cloneable, java.io.Serializable |
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{ |
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private static final long serialVersionUID = 8683452581122892189L; |
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|
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/** |
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* The array buffer into which the elements of the ArrayList are stored. |
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* The capacity of the ArrayList is the length of this array buffer. |
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*/ |
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private transient Object[] elementData; |
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|
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/** |
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* The size of the ArrayList (the number of elements it contains). |
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* |
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* @serial |
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*/ |
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private int size; |
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|
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/** |
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* Constructs an empty list with the specified initial capacity. |
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* |
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* @param initialCapacity the initial capacity of the list |
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* @exception IllegalArgumentException if the specified initial capacity |
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* is negative |
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*/ |
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public ArrayList(int initialCapacity) { |
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super(); |
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if (initialCapacity < 0) |
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throw new IllegalArgumentException("Illegal Capacity: "+ |
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initialCapacity); |
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this.elementData = new Object[initialCapacity]; |
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} |
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|
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/** |
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* Constructs an empty list with an initial capacity of ten. |
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*/ |
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public ArrayList() { |
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this(10); |
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} |
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|
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/** |
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* Constructs a list containing the elements of the specified |
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* collection, in the order they are returned by the collection's |
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* iterator. The <tt>ArrayList</tt> instance has an initial capacity of |
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* 110% the size of the specified collection. |
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* |
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* @param c the collection whose elements are to be placed into this list |
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* @throws NullPointerException if the specified collection is null |
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*/ |
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public ArrayList(Collection<? extends E> c) { |
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int size = c.size(); |
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// 10% for growth |
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int cap = ((size/10)+1)*11; |
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if (cap > 0) { |
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Object[] a = new Object[cap]; |
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a[size] = a[size+1] = UNALLOCATED; |
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Object[] b = c.toArray(a); |
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if (b[size] == null && b[size+1] == UNALLOCATED) { |
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b[size+1] = null; |
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elementData = b; |
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this.size = size; |
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return; |
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} |
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} |
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initFromConcurrentlyMutating(c); |
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} |
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|
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private void initFromConcurrentlyMutating(Collection<? extends E> c) { |
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elementData = c.toArray(); |
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size = elementData.length; |
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// c.toArray might (incorrectly) not return Object[] (see 6260652) |
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if (elementData.getClass() != Object[].class) |
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elementData = Arrays.copyOf(elementData, size, Object[].class); |
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} |
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|
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private final static Object UNALLOCATED = new Object(); |
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|
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/** |
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* Trims the capacity of this <tt>ArrayList</tt> instance to be the |
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* list's current size. An application can use this operation to minimize |
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* the storage of an <tt>ArrayList</tt> instance. |
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*/ |
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public void trimToSize() { |
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modCount++; |
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int oldCapacity = elementData.length; |
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if (size < oldCapacity) { |
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elementData = Arrays.copyOf(elementData, size); |
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} |
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} |
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|
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/** |
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* Increases the capacity of this <tt>ArrayList</tt> instance, if |
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* necessary, to ensure that it can hold at least the number of elements |
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* specified by the minimum capacity argument. |
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* |
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* @param minCapacity the desired minimum capacity |
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*/ |
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/** |
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* Increases the capacity of this <tt>ArrayList</tt> instance, if |
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* necessary, to ensure that it can hold at least the number of elements |
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* specified by the minimum capacity argument. |
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* |
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* @param minCapacity the desired minimum capacity |
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*/ |
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public void ensureCapacity(int minCapacity) { |
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modCount++; |
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if (minCapacity > elementData.length) |
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growArray(minCapacity); |
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} |
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|
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/** |
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* Increase the capacity of the array. |
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* @param minCapacity the desired minimum capacity |
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*/ |
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private void growArray(int minCapacity) { |
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int oldCapacity = elementData.length; |
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// Double size if small; else grow by 50% |
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int newCapacity = ((oldCapacity < 64)? |
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(oldCapacity * 2): |
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((oldCapacity * 3)/2 + 1)); |
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if (newCapacity < minCapacity) |
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newCapacity = minCapacity; |
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elementData = Arrays.copyOf(elementData, newCapacity); |
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} |
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|
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/** |
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* Returns the number of elements in this list. |
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* |
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* @return the number of elements in this list |
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*/ |
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public int size() { |
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return size; |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this list contains no elements. |
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* |
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* @return <tt>true</tt> if this list contains no elements |
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*/ |
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public boolean isEmpty() { |
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return size == 0; |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this list contains the specified element. |
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* More formally, returns <tt>true</tt> if and only if this list contains |
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* at least one element <tt>e</tt> such that |
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* <tt>(o==null ? e==null : o.equals(e))</tt>. |
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* |
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* @param o element whose presence in this list is to be tested |
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* @return <tt>true</tt> if this list contains the specified element |
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*/ |
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public boolean contains(Object o) { |
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return indexOf(o) >= 0; |
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} |
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|
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/** |
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* Returns the index of the first occurrence of the specified element |
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* in this list, or -1 if this list does not contain the element. |
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* More formally, returns the lowest index <tt>i</tt> such that |
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* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
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* or -1 if there is no such index. |
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*/ |
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public int indexOf(Object o) { |
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if (o == null) { |
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for (int i = 0; i < size; i++) |
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if (elementData[i]==null) |
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return i; |
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} else { |
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for (int i = 0; i < size; i++) |
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if (o.equals(elementData[i])) |
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return i; |
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} |
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return -1; |
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} |
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|
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/** |
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* Returns the index of the last occurrence of the specified element |
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* in this list, or -1 if this list does not contain the element. |
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* More formally, returns the highest index <tt>i</tt> such that |
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* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
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* or -1 if there is no such index. |
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*/ |
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public int lastIndexOf(Object o) { |
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if (o == null) { |
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for (int i = size-1; i >= 0; i--) |
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if (elementData[i]==null) |
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return i; |
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} else { |
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for (int i = size-1; i >= 0; i--) |
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if (o.equals(elementData[i])) |
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return i; |
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} |
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return -1; |
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} |
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|
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/** |
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* Returns a shallow copy of this <tt>ArrayList</tt> instance. (The |
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* elements themselves are not copied.) |
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* |
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* @return a clone of this <tt>ArrayList</tt> instance |
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*/ |
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public Object clone() { |
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try { |
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ArrayList<E> v = (ArrayList<E>) super.clone(); |
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v.elementData = Arrays.copyOf(elementData, size); |
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v.modCount = 0; |
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return v; |
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} catch (CloneNotSupportedException e) { |
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// this shouldn't happen, since we are Cloneable |
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throw new InternalError(); |
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} |
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} |
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|
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/** |
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* Returns an array containing all of the elements in this list |
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* in proper sequence (from first to last element). |
300 |
* |
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* <p>The returned array will be "safe" in that no references to it are |
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* maintained by this list. (In other words, this method must allocate |
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* a new array). The caller is thus free to modify the returned array. |
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* |
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* <p>This method acts as bridge between array-based and collection-based |
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* APIs. |
307 |
* |
308 |
* @return an array containing all of the elements in this list in |
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* proper sequence |
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*/ |
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public Object[] toArray() { |
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return Arrays.copyOf(elementData, size); |
313 |
} |
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|
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/** |
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* Returns an array containing all of the elements in this list in proper |
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* sequence (from first to last element); the runtime type of the returned |
318 |
* array is that of the specified array. If the list fits in the |
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* specified array, it is returned therein. Otherwise, a new array is |
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* allocated with the runtime type of the specified array and the size of |
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* this list. |
322 |
* |
323 |
* <p>If the list fits in the specified array with room to spare |
324 |
* (i.e., the array has more elements than the list), the element in |
325 |
* the array immediately following the end of the collection is set to |
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* <tt>null</tt>. (This is useful in determining the length of the |
327 |
* list <i>only</i> if the caller knows that the list does not contain |
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* any null elements.) |
329 |
* |
330 |
* @param a the array into which the elements of the list are to |
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* be stored, if it is big enough; otherwise, a new array of the |
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* same runtime type is allocated for this purpose. |
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* @return an array containing the elements of the list |
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* @throws ArrayStoreException if the runtime type of the specified array |
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* is not a supertype of the runtime type of every element in |
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* this list |
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* @throws NullPointerException if the specified array is null |
338 |
*/ |
339 |
public <T> T[] toArray(T[] a) { |
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if (a.length < size) |
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// Make a new array of a's runtime type, but my contents: |
342 |
return (T[]) Arrays.copyOf(elementData, size, a.getClass()); |
343 |
System.arraycopy(elementData, 0, a, 0, size); |
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if (a.length > size) |
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a[size] = null; |
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return a; |
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} |
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|
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// Positional Access Operations |
350 |
|
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/** |
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* Create and return an appropriate exception for indexing errors |
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*/ |
354 |
private static IndexOutOfBoundsException rangeException(int i, int s) { |
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return new IndexOutOfBoundsException("Index: " + i + ", Size: " + s); |
356 |
} |
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|
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// Positional Access Operations |
359 |
|
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/** |
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* Returns the element at the specified position in this list. |
362 |
* |
363 |
* @param index index of the element to return |
364 |
* @return the element at the specified position in this list |
365 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
366 |
*/ |
367 |
public E get(int index) { |
368 |
if (index >= size) |
369 |
throw rangeException(index, size); |
370 |
return (E)elementData[index]; |
371 |
} |
372 |
|
373 |
/** |
374 |
* Replaces the element at the specified position in this list with |
375 |
* the specified element. |
376 |
* |
377 |
* @param index index of the element to replace |
378 |
* @param element element to be stored at the specified position |
379 |
* @return the element previously at the specified position |
380 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
381 |
*/ |
382 |
public E set(int index, E element) { |
383 |
if (index >= size) |
384 |
throw rangeException(index, size); |
385 |
|
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E oldValue = (E) elementData[index]; |
387 |
elementData[index] = element; |
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return oldValue; |
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} |
390 |
|
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/** |
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* Appends the specified element to the end of this list. |
393 |
* |
394 |
* @param e element to be appended to this list |
395 |
* @return <tt>true</tt> (as specified by {@link Collection#add}) |
396 |
*/ |
397 |
public boolean add(E e) { |
398 |
++modCount; |
399 |
int s = size++; |
400 |
if (s >= elementData.length) |
401 |
growArray(s + 1); |
402 |
elementData[s] = e; |
403 |
return true; |
404 |
} |
405 |
|
406 |
/** |
407 |
* Inserts the specified element at the specified position in this |
408 |
* list. Shifts the element currently at that position (if any) and |
409 |
* any subsequent elements to the right (adds one to their indices). |
410 |
* |
411 |
* @param index index at which the specified element is to be inserted |
412 |
* @param element element to be inserted |
413 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
414 |
*/ |
415 |
public void add(int index, E element) { |
416 |
int s = size; |
417 |
if (index > s || index < 0) |
418 |
throw rangeException(index, s); |
419 |
++modCount; |
420 |
size = s + 1; |
421 |
if (s >= elementData.length) |
422 |
growArray(s + 1); |
423 |
System.arraycopy(elementData, index, elementData, index + 1, |
424 |
s - index); |
425 |
elementData[index] = element; |
426 |
} |
427 |
|
428 |
/** |
429 |
* Removes the element at the specified position in this list. |
430 |
* Shifts any subsequent elements to the left (subtracts one from their |
431 |
* indices). |
432 |
* |
433 |
* @param index the index of the element to be removed |
434 |
* @return the element that was removed from the list |
435 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
436 |
*/ |
437 |
public E remove(int index) { |
438 |
int s = size - 1; |
439 |
if (index > s) |
440 |
throw rangeException(index, size); |
441 |
size = s; |
442 |
modCount++; |
443 |
Object oldValue = elementData[index]; |
444 |
int numMoved = s - index; |
445 |
if (numMoved > 0) |
446 |
System.arraycopy(elementData, index+1, elementData, index, |
447 |
numMoved); |
448 |
elementData[s] = null; // forget removed element |
449 |
return (E)oldValue; |
450 |
} |
451 |
|
452 |
/** |
453 |
* Removes the first occurrence of the specified element from this list, |
454 |
* if it is present. If the list does not contain the element, it is |
455 |
* unchanged. More formally, removes the element with the lowest index |
456 |
* <tt>i</tt> such that |
457 |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> |
458 |
* (if such an element exists). Returns <tt>true</tt> if this list |
459 |
* contained the specified element (or equivalently, if this list |
460 |
* changed as a result of the call). |
461 |
* |
462 |
* @param o element to be removed from this list, if present |
463 |
* @return <tt>true</tt> if this list contained the specified element |
464 |
*/ |
465 |
public boolean remove(Object o) { |
466 |
if (o == null) { |
467 |
for (int index = 0; index < size; index++) |
468 |
if (elementData[index] == null) { |
469 |
fastRemove(index); |
470 |
return true; |
471 |
} |
472 |
} else { |
473 |
for (int index = 0; index < size; index++) |
474 |
if (o.equals(elementData[index])) { |
475 |
fastRemove(index); |
476 |
return true; |
477 |
} |
478 |
} |
479 |
return false; |
480 |
} |
481 |
|
482 |
/* |
483 |
* Private remove method that skips bounds checking and does not |
484 |
* return the value removed. |
485 |
*/ |
486 |
private void fastRemove(int index) { |
487 |
modCount++; |
488 |
int numMoved = size - index - 1; |
489 |
if (numMoved > 0) |
490 |
System.arraycopy(elementData, index+1, elementData, index, |
491 |
numMoved); |
492 |
elementData[--size] = null; // Let gc do its work |
493 |
} |
494 |
|
495 |
/** |
496 |
* Removes all of the elements from this list. The list will |
497 |
* be empty after this call returns. |
498 |
*/ |
499 |
public void clear() { |
500 |
modCount++; |
501 |
|
502 |
// Let gc do its work |
503 |
for (int i = 0; i < size; i++) |
504 |
elementData[i] = null; |
505 |
|
506 |
size = 0; |
507 |
} |
508 |
|
509 |
/** |
510 |
* Appends all of the elements in the specified collection to the end of |
511 |
* this list, in the order that they are returned by the |
512 |
* specified collection's Iterator. The behavior of this operation is |
513 |
* undefined if the specified collection is modified while the operation |
514 |
* is in progress. (This implies that the behavior of this call is |
515 |
* undefined if the specified collection is this list, and this |
516 |
* list is nonempty.) |
517 |
* |
518 |
* @param c collection containing elements to be added to this list |
519 |
* @return <tt>true</tt> if this list changed as a result of the call |
520 |
* @throws NullPointerException if the specified collection is null |
521 |
*/ |
522 |
public boolean addAll(Collection<? extends E> c) { |
523 |
Object[] a = c.toArray(); |
524 |
int numNew = a.length; |
525 |
ensureCapacity(size + numNew); // Increments modCount |
526 |
System.arraycopy(a, 0, elementData, size, numNew); |
527 |
size += numNew; |
528 |
return numNew != 0; |
529 |
} |
530 |
|
531 |
/** |
532 |
* Inserts all of the elements in the specified collection into this |
533 |
* list, starting at the specified position. Shifts the element |
534 |
* currently at that position (if any) and any subsequent elements to |
535 |
* the right (increases their indices). The new elements will appear |
536 |
* in the list in the order that they are returned by the |
537 |
* specified collection's iterator. |
538 |
* |
539 |
* @param index index at which to insert the first element from the |
540 |
* specified collection |
541 |
* @param c collection containing elements to be added to this list |
542 |
* @return <tt>true</tt> if this list changed as a result of the call |
543 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
544 |
* @throws NullPointerException if the specified collection is null |
545 |
*/ |
546 |
public boolean addAll(int index, Collection<? extends E> c) { |
547 |
if (index > size || index < 0) |
548 |
throw new IndexOutOfBoundsException( |
549 |
"Index: " + index + ", Size: " + size); |
550 |
|
551 |
Object[] a = c.toArray(); |
552 |
int numNew = a.length; |
553 |
ensureCapacity(size + numNew); // Increments modCount |
554 |
|
555 |
int numMoved = size - index; |
556 |
if (numMoved > 0) |
557 |
System.arraycopy(elementData, index, elementData, index + numNew, |
558 |
numMoved); |
559 |
|
560 |
System.arraycopy(a, 0, elementData, index, numNew); |
561 |
size += numNew; |
562 |
return numNew != 0; |
563 |
} |
564 |
|
565 |
/** |
566 |
* Removes from this list all of the elements whose index is between |
567 |
* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. |
568 |
* Shifts any succeeding elements to the left (reduces their index). |
569 |
* This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements. |
570 |
* (If <tt>toIndex==fromIndex</tt>, this operation has no effect.) |
571 |
* |
572 |
* @param fromIndex index of first element to be removed |
573 |
* @param toIndex index after last element to be removed |
574 |
* @throws IndexOutOfBoundsException if fromIndex or toIndex out of |
575 |
* range (fromIndex < 0 || fromIndex >= size() || toIndex |
576 |
* > size() || toIndex < fromIndex) |
577 |
*/ |
578 |
protected void removeRange(int fromIndex, int toIndex) { |
579 |
modCount++; |
580 |
int numMoved = size - toIndex; |
581 |
System.arraycopy(elementData, toIndex, elementData, fromIndex, |
582 |
numMoved); |
583 |
|
584 |
// Let gc do its work |
585 |
int newSize = size - (toIndex-fromIndex); |
586 |
while (size != newSize) |
587 |
elementData[--size] = null; |
588 |
} |
589 |
|
590 |
/** |
591 |
* Save the state of the <tt>ArrayList</tt> instance to a stream (that |
592 |
* is, serialize it). |
593 |
* |
594 |
* @serialData The length of the array backing the <tt>ArrayList</tt> |
595 |
* instance is emitted (int), followed by all of its elements |
596 |
* (each an <tt>Object</tt>) in the proper order. |
597 |
*/ |
598 |
private void writeObject(java.io.ObjectOutputStream s) |
599 |
throws java.io.IOException{ |
600 |
// Write out element count, and any hidden stuff |
601 |
int expectedModCount = modCount; |
602 |
s.defaultWriteObject(); |
603 |
|
604 |
// Write out array length |
605 |
s.writeInt(elementData.length); |
606 |
|
607 |
// Write out all elements in the proper order. |
608 |
for (int i=0; i<size; i++) |
609 |
s.writeObject(elementData[i]); |
610 |
|
611 |
if (modCount != expectedModCount) { |
612 |
throw new ConcurrentModificationException(); |
613 |
} |
614 |
|
615 |
} |
616 |
|
617 |
/** |
618 |
* Reconstitute the <tt>ArrayList</tt> instance from a stream (that is, |
619 |
* deserialize it). |
620 |
*/ |
621 |
private void readObject(java.io.ObjectInputStream s) |
622 |
throws java.io.IOException, ClassNotFoundException { |
623 |
// Read in size, and any hidden stuff |
624 |
s.defaultReadObject(); |
625 |
|
626 |
// Read in array length and allocate array |
627 |
int arrayLength = s.readInt(); |
628 |
Object[] a = elementData = new Object[arrayLength]; |
629 |
|
630 |
// Read in all elements in the proper order. |
631 |
for (int i=0; i<size; i++) |
632 |
a[i] = s.readObject(); |
633 |
} |
634 |
|
635 |
|
636 |
/** |
637 |
* Returns a list-iterator of the elements in this list (in proper |
638 |
* sequence), starting at the specified position in the list. |
639 |
* Obeys the general contract of <tt>List.listIterator(int)</tt>.<p> |
640 |
* |
641 |
* The list-iterator is <i>fail-fast</i>: if the list is structurally |
642 |
* modified at any time after the Iterator is created, in any way except |
643 |
* through the list-iterator's own <tt>remove</tt> or <tt>add</tt> |
644 |
* methods, the list-iterator will throw a |
645 |
* <tt>ConcurrentModificationException</tt>. Thus, in the face of |
646 |
* concurrent modification, the iterator fails quickly and cleanly, rather |
647 |
* than risking arbitrary, non-deterministic behavior at an undetermined |
648 |
* time in the future. |
649 |
* |
650 |
* @param index index of the first element to be returned from the |
651 |
* list-iterator (by a call to <tt>next</tt>) |
652 |
* @return a ListIterator of the elements in this list (in proper |
653 |
* sequence), starting at the specified position in the list |
654 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
655 |
* @see List#listIterator(int) |
656 |
*/ |
657 |
public ListIterator<E> listIterator(int index) { |
658 |
if (index < 0 || index > size) |
659 |
throw new IndexOutOfBoundsException("Index: "+index); |
660 |
return new ArrayListIterator(index); |
661 |
} |
662 |
|
663 |
/** |
664 |
* Returns an iterator over the elements in this list in proper sequence. |
665 |
* |
666 |
* @return an iterator over the elements in this list in proper sequence |
667 |
*/ |
668 |
public Iterator<E> iterator() { |
669 |
return new ArrayListIterator(0); |
670 |
} |
671 |
|
672 |
/** |
673 |
* A streamlined version of AbstractList.Itr |
674 |
*/ |
675 |
final class ArrayListIterator implements ListIterator<E> { |
676 |
int cursor; // index of next element to return; |
677 |
int lastRet; // index of last element, or -1 if no such |
678 |
int expectedModCount; // to check for CME |
679 |
|
680 |
ArrayListIterator(int index) { |
681 |
cursor = index; |
682 |
lastRet = -1; |
683 |
expectedModCount = modCount; |
684 |
} |
685 |
|
686 |
public boolean hasNext() { |
687 |
return cursor < size; |
688 |
} |
689 |
|
690 |
public boolean hasPrevious() { |
691 |
return cursor > 0; |
692 |
} |
693 |
|
694 |
public int nextIndex() { |
695 |
return cursor; |
696 |
} |
697 |
|
698 |
public int previousIndex() { |
699 |
return cursor - 1; |
700 |
} |
701 |
|
702 |
public E next() { |
703 |
if (expectedModCount == modCount) { |
704 |
int i = cursor; |
705 |
if (i < size) { |
706 |
try { |
707 |
E e = (E)elementData[i]; |
708 |
lastRet = i; |
709 |
cursor = i + 1; |
710 |
return e; |
711 |
} catch (IndexOutOfBoundsException fallthrough) { |
712 |
} |
713 |
} |
714 |
} |
715 |
// Prefer reporting CME if applicable on failures |
716 |
if (expectedModCount == modCount) |
717 |
throw new NoSuchElementException(); |
718 |
throw new ConcurrentModificationException(); |
719 |
} |
720 |
|
721 |
public E previous() { |
722 |
if (expectedModCount == modCount) { |
723 |
int i = cursor - 1; |
724 |
if (i < size) { |
725 |
try { |
726 |
E e = (E)elementData[i]; |
727 |
lastRet = i; |
728 |
cursor = i; |
729 |
return e; |
730 |
} catch (IndexOutOfBoundsException fallthrough) { |
731 |
} |
732 |
} |
733 |
} |
734 |
if (expectedModCount == modCount) |
735 |
throw new NoSuchElementException(); |
736 |
throw new ConcurrentModificationException(); |
737 |
} |
738 |
|
739 |
public void remove() { |
740 |
if (lastRet < 0) |
741 |
throw new IllegalStateException(); |
742 |
if (modCount != expectedModCount) |
743 |
throw new ConcurrentModificationException(); |
744 |
ArrayList.this.remove(lastRet); |
745 |
if (lastRet < cursor) |
746 |
cursor--; |
747 |
lastRet = -1; |
748 |
expectedModCount = modCount; |
749 |
} |
750 |
|
751 |
public void set(E e) { |
752 |
if (lastRet < 0) |
753 |
throw new IllegalStateException(); |
754 |
if (modCount != expectedModCount) |
755 |
throw new ConcurrentModificationException(); |
756 |
ArrayList.this.set(lastRet, e); |
757 |
expectedModCount = modCount; |
758 |
} |
759 |
|
760 |
public void add(E e) { |
761 |
if (modCount != expectedModCount) |
762 |
throw new ConcurrentModificationException(); |
763 |
ArrayList.this.add(cursor++, e); |
764 |
lastRet = -1; |
765 |
expectedModCount = modCount; |
766 |
} |
767 |
} |
768 |
|
769 |
} |