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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/util/ArrayList.java
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+/* ArrayList.java -- JDK1.2's answer to Vector; this is an array-backed
+ implementation of the List interface
+ Copyright (C) 1998, 1999, 2000, 2001, 2004, 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package java.util;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+import java.lang.reflect.Array;
+
+/**
+ * An array-backed implementation of the List interface. This implements
+ * all optional list operations, and permits null elements, so that it is
+ * better than Vector, which it replaces. Random access is roughly constant
+ * time, and iteration is roughly linear time, so it is nice and fast, with
+ * less overhead than a LinkedList.
+ * <p>
+ *
+ * Each list has a capacity, and as the array reaches that capacity it
+ * is automatically transferred to a larger array. You also have access to
+ * ensureCapacity and trimToSize to control the backing array's size, avoiding
+ * reallocation or wasted memory.
+ * <p>
+ *
+ * ArrayList is not synchronized, so if you need multi-threaded access,
+ * consider using:<br>
+ * <code>List l = Collections.synchronizedList(new ArrayList(...));</code>
+ * <p>
+ *
+ * The iterators are <i>fail-fast</i>, meaning that any structural
+ * modification, except for <code>remove()</code> called on the iterator
+ * itself, cause the iterator to throw a
+ * {@link ConcurrentModificationException} rather than exhibit
+ * non-deterministic behavior.
+ *
+ * @author Jon A. Zeppieri
+ * @author Bryce McKinlay
+ * @author Eric Blake (ebb9@email.byu.edu)
+ * @see Collection
+ * @see List
+ * @see LinkedList
+ * @see Vector
+ * @see Collections#synchronizedList(List)
+ * @see AbstractList
+ * @status updated to 1.4
+ */
+public class ArrayList<E> extends AbstractList<E>
+ implements List<E>, RandomAccess, Cloneable, Serializable
+{
+ /**
+ * Compatible with JDK 1.2
+ */
+ private static final long serialVersionUID = 8683452581122892189L;
+
+ /**
+ * The default capacity for new ArrayLists.
+ */
+ private static final int DEFAULT_CAPACITY = 10;
+
+ /**
+ * The number of elements in this list.
+ * @serial the list size
+ */
+ private int size;
+
+ /**
+ * Where the data is stored.
+ */
+ private transient E[] data;
+
+ /**
+ * Construct a new ArrayList with the supplied initial capacity.
+ *
+ * @param capacity initial capacity of this ArrayList
+ * @throws IllegalArgumentException if capacity is negative
+ */
+ public ArrayList(int capacity)
+ {
+ // Must explicitly check, to get correct exception.
+ if (capacity < 0)
+ throw new IllegalArgumentException();
+ data = (E[]) new Object[capacity];
+ }
+
+ /**
+ * Construct a new ArrayList with the default capacity (16).
+ */
+ public ArrayList()
+ {
+ this(DEFAULT_CAPACITY);
+ }
+
+ /**
+ * Construct a new ArrayList, and initialize it with the elements
+ * in the supplied Collection. The initial capacity is 110% of the
+ * Collection's size.
+ *
+ * @param c the collection whose elements will initialize this list
+ * @throws NullPointerException if c is null
+ */
+ public ArrayList(Collection<? extends E> c)
+ {
+ this((int) (c.size() * 1.1f));
+ addAll(c);
+ }
+
+ /**
+ * Trims the capacity of this List to be equal to its size;
+ * a memory saver.
+ */
+ public void trimToSize()
+ {
+ // Not a structural change from the perspective of iterators on this list,
+ // so don't update modCount.
+ if (size != data.length)
+ {
+ E[] newData = (E[]) new Object[size];
+ System.arraycopy(data, 0, newData, 0, size);
+ data = newData;
+ }
+ }
+
+ /**
+ * Guarantees that this list will have at least enough capacity to
+ * hold minCapacity elements. This implementation will grow the list to
+ * max(current * 2, minCapacity) if (minCapacity &gt; current). The JCL says
+ * explictly that "this method increases its capacity to minCap", while
+ * the JDK 1.3 online docs specify that the list will grow to at least the
+ * size specified.
+ *
+ * @param minCapacity the minimum guaranteed capacity
+ */
+ public void ensureCapacity(int minCapacity)
+ {
+ int current = data.length;
+
+ if (minCapacity > current)
+ {
+ E[] newData = (E[]) new Object[Math.max(current * 2, minCapacity)];
+ System.arraycopy(data, 0, newData, 0, size);
+ data = newData;
+ }
+ }
+
+ /**
+ * Returns the number of elements in this list.
+ *
+ * @return the list size
+ */
+ public int size()
+ {
+ return size;
+ }
+
+ /**
+ * Checks if the list is empty.
+ *
+ * @return true if there are no elements
+ */
+ public boolean isEmpty()
+ {
+ return size == 0;
+ }
+
+ /**
+ * Returns true iff element is in this ArrayList.
+ *
+ * @param e the element whose inclusion in the List is being tested
+ * @return true if the list contains e
+ */
+ public boolean contains(Object e)
+ {
+ return indexOf(e) != -1;
+ }
+
+ /**
+ * Returns the lowest index at which element appears in this List, or
+ * -1 if it does not appear.
+ *
+ * @param e the element whose inclusion in the List is being tested
+ * @return the index where e was found
+ */
+ public int indexOf(Object e)
+ {
+ for (int i = 0; i < size; i++)
+ if (equals(e, data[i]))
+ return i;
+ return -1;
+ }
+
+ /**
+ * Returns the highest index at which element appears in this List, or
+ * -1 if it does not appear.
+ *
+ * @param e the element whose inclusion in the List is being tested
+ * @return the index where e was found
+ */
+ public int lastIndexOf(Object e)
+ {
+ for (int i = size - 1; i >= 0; i--)
+ if (equals(e, data[i]))
+ return i;
+ return -1;
+ }
+
+ /**
+ * Creates a shallow copy of this ArrayList (elements are not cloned).
+ *
+ * @return the cloned object
+ */
+ public Object clone()
+ {
+ ArrayList<E> clone = null;
+ try
+ {
+ clone = (ArrayList<E>) super.clone();
+ clone.data = (E[]) data.clone();
+ }
+ catch (CloneNotSupportedException e)
+ {
+ // Impossible to get here.
+ }
+ return clone;
+ }
+
+ /**
+ * Returns an Object array containing all of the elements in this ArrayList.
+ * The array is independent of this list.
+ *
+ * @return an array representation of this list
+ */
+ public Object[] toArray()
+ {
+ E[] array = (E[]) new Object[size];
+ System.arraycopy(data, 0, array, 0, size);
+ return array;
+ }
+
+ /**
+ * Returns an Array whose component type is the runtime component type of
+ * the passed-in Array. The returned Array is populated with all of the
+ * elements in this ArrayList. If the passed-in Array is not large enough
+ * to store all of the elements in this List, a new Array will be created
+ * and returned; if the passed-in Array is <i>larger</i> than the size
+ * of this List, then size() index will be set to null.
+ *
+ * @param a the passed-in Array
+ * @return an array representation of this list
+ * @throws ArrayStoreException if the runtime type of a does not allow
+ * an element in this list
+ * @throws NullPointerException if a is null
+ */
+ public <T> T[] toArray(T[] a)
+ {
+ if (a.length < size)
+ a = (T[]) Array.newInstance(a.getClass().getComponentType(), size);
+ else if (a.length > size)
+ a[size] = null;
+ System.arraycopy(data, 0, a, 0, size);
+ return a;
+ }
+
+ /**
+ * Retrieves the element at the user-supplied index.
+ *
+ * @param index the index of the element we are fetching
+ * @throws IndexOutOfBoundsException if index &lt; 0 || index &gt;= size()
+ */
+ public E get(int index)
+ {
+ checkBoundExclusive(index);
+ return data[index];
+ }
+
+ /**
+ * Sets the element at the specified index. The new element, e,
+ * can be an object of any type or null.
+ *
+ * @param index the index at which the element is being set
+ * @param e the element to be set
+ * @return the element previously at the specified index
+ * @throws IndexOutOfBoundsException if index &lt; 0 || index &gt;= 0
+ */
+ public E set(int index, E e)
+ {
+ checkBoundExclusive(index);
+ E result = data[index];
+ data[index] = e;
+ return result;
+ }
+
+ /**
+ * Appends the supplied element to the end of this list.
+ * The element, e, can be an object of any type or null.
+ *
+ * @param e the element to be appended to this list
+ * @return true, the add will always succeed
+ */
+ public boolean add(E e)
+ {
+ modCount++;
+ if (size == data.length)
+ ensureCapacity(size + 1);
+ data[size++] = e;
+ return true;
+ }
+
+ /**
+ * Adds the supplied element at the specified index, shifting all
+ * elements currently at that index or higher one to the right.
+ * The element, e, can be an object of any type or null.
+ *
+ * @param index the index at which the element is being added
+ * @param e the item being added
+ * @throws IndexOutOfBoundsException if index &lt; 0 || index &gt; size()
+ */
+ public void add(int index, E e)
+ {
+ checkBoundInclusive(index);
+ modCount++;
+ if (size == data.length)
+ ensureCapacity(size + 1);
+ if (index != size)
+ System.arraycopy(data, index, data, index + 1, size - index);
+ data[index] = e;
+ size++;
+ }
+
+ /**
+ * Removes the element at the user-supplied index.
+ *
+ * @param index the index of the element to be removed
+ * @return the removed Object
+ * @throws IndexOutOfBoundsException if index &lt; 0 || index &gt;= size()
+ */
+ public E remove(int index)
+ {
+ checkBoundExclusive(index);
+ E r = data[index];
+ modCount++;
+ if (index != --size)
+ System.arraycopy(data, index + 1, data, index, size - index);
+ // Aid for garbage collection by releasing this pointer.
+ data[size] = null;
+ return r;
+ }
+
+ /**
+ * Removes all elements from this List
+ */
+ public void clear()
+ {
+ if (size > 0)
+ {
+ modCount++;
+ // Allow for garbage collection.
+ Arrays.fill(data, 0, size, null);
+ size = 0;
+ }
+ }
+
+ /**
+ * Add each element in the supplied Collection to this List. It is undefined
+ * what happens if you modify the list while this is taking place; for
+ * example, if the collection contains this list. c can contain objects
+ * of any type, as well as null values.
+ *
+ * @param c a Collection containing elements to be added to this List
+ * @return true if the list was modified, in other words c is not empty
+ * @throws NullPointerException if c is null
+ */
+ public boolean addAll(Collection<? extends E> c)
+ {
+ return addAll(size, c);
+ }
+
+ /**
+ * Add all elements in the supplied collection, inserting them beginning
+ * at the specified index. c can contain objects of any type, as well
+ * as null values.
+ *
+ * @param index the index at which the elements will be inserted
+ * @param c the Collection containing the elements to be inserted
+ * @throws IndexOutOfBoundsException if index &lt; 0 || index &gt; 0
+ * @throws NullPointerException if c is null
+ */
+ public boolean addAll(int index, Collection<? extends E> c)
+ {
+ checkBoundInclusive(index);
+ Iterator<? extends E> itr = c.iterator();
+ int csize = c.size();
+
+ modCount++;
+ if (csize + size > data.length)
+ ensureCapacity(size + csize);
+ int end = index + csize;
+ if (size > 0 && index != size)
+ System.arraycopy(data, index, data, end, size - index);
+ size += csize;
+ for ( ; index < end; index++)
+ data[index] = itr.next();
+ return csize > 0;
+ }
+
+ /**
+ * Removes all elements in the half-open interval [fromIndex, toIndex).
+ * Does nothing when toIndex is equal to fromIndex.
+ *
+ * @param fromIndex the first index which will be removed
+ * @param toIndex one greater than the last index which will be removed
+ * @throws IndexOutOfBoundsException if fromIndex &gt; toIndex
+ */
+ protected void removeRange(int fromIndex, int toIndex)
+ {
+ int change = toIndex - fromIndex;
+ if (change > 0)
+ {
+ modCount++;
+ System.arraycopy(data, toIndex, data, fromIndex, size - toIndex);
+ size -= change;
+ }
+ else if (change < 0)
+ throw new IndexOutOfBoundsException();
+ }
+
+ /**
+ * Checks that the index is in the range of possible elements (inclusive).
+ *
+ * @param index the index to check
+ * @throws IndexOutOfBoundsException if index &gt; size
+ */
+ private void checkBoundInclusive(int index)
+ {
+ // Implementation note: we do not check for negative ranges here, since
+ // use of a negative index will cause an ArrayIndexOutOfBoundsException,
+ // a subclass of the required exception, with no effort on our part.
+ if (index > size)
+ raiseBoundsError(index);
+ }
+
+ /**
+ * Checks that the index is in the range of existing elements (exclusive).
+ *
+ * @param index the index to check
+ * @throws IndexOutOfBoundsException if index &gt;= size
+ */
+ private void checkBoundExclusive(int index)
+ {
+ // Implementation note: we do not check for negative ranges here, since
+ // use of a negative index will cause an ArrayIndexOutOfBoundsException,
+ // a subclass of the required exception, with no effort on our part.
+ if (index >= size)
+ raiseBoundsError(index);
+ }
+
+ /**
+ * Raise the ArrayIndexOfOutBoundsException.
+ *
+ * @param index the index of the access
+ * @throws IndexOutOfBoundsException unconditionally
+ */
+ private void raiseBoundsError(int index)
+ {
+ // Implementaion note: put in a separate method to make the JITs job easier
+ // (separate common from uncommon code at method boundaries when trivial to
+ // do so).
+ throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + size);
+ }
+
+
+ /**
+ * Remove from this list all elements contained in the given collection.
+ * This is not public, due to Sun's API, but this performs in linear
+ * time while the default behavior of AbstractList would be quadratic.
+ *
+ * @param c the collection to filter out
+ * @return true if this list changed
+ * @throws NullPointerException if c is null
+ */
+ boolean removeAllInternal(Collection<?> c)
+ {
+ int i;
+ int j;
+ for (i = 0; i < size; i++)
+ if (c.contains(data[i]))
+ break;
+ if (i == size)
+ return false;
+
+ modCount++;
+ for (j = i++; i < size; i++)
+ if (! c.contains(data[i]))
+ data[j++] = data[i];
+ size -= i - j;
+ return true;
+ }
+
+ /**
+ * Retain in this vector only the elements contained in the given collection.
+ * This is not public, due to Sun's API, but this performs in linear
+ * time while the default behavior of AbstractList would be quadratic.
+ *
+ * @param c the collection to filter by
+ * @return true if this vector changed
+ * @throws NullPointerException if c is null
+ * @since 1.2
+ */
+ boolean retainAllInternal(Collection<?> c)
+ {
+ int i;
+ int j;
+ for (i = 0; i < size; i++)
+ if (! c.contains(data[i]))
+ break;
+ if (i == size)
+ return false;
+
+ modCount++;
+ for (j = i++; i < size; i++)
+ if (c.contains(data[i]))
+ data[j++] = data[i];
+ size -= i - j;
+ return true;
+ }
+
+ /**
+ * Serializes this object to the given stream.
+ *
+ * @param s the stream to write to
+ * @throws IOException if the underlying stream fails
+ * @serialData the size field (int), the length of the backing array
+ * (int), followed by its elements (Objects) in proper order.
+ */
+ private void writeObject(ObjectOutputStream s) throws IOException
+ {
+ // The 'size' field.
+ s.defaultWriteObject();
+ // We serialize unused list entries to preserve capacity.
+ int len = data.length;
+ s.writeInt(len);
+ // it would be more efficient to just write "size" items,
+ // this need readObject read "size" items too.
+ for (int i = 0; i < size; i++)
+ s.writeObject(data[i]);
+ }
+
+ /**
+ * Deserializes this object from the given stream.
+ *
+ * @param s the stream to read from
+ * @throws ClassNotFoundException if the underlying stream fails
+ * @throws IOException if the underlying stream fails
+ * @serialData the size field (int), the length of the backing array
+ * (int), followed by its elements (Objects) in proper order.
+ */
+ private void readObject(ObjectInputStream s)
+ throws IOException, ClassNotFoundException
+ {
+ // the `size' field.
+ s.defaultReadObject();
+ int capacity = s.readInt();
+ data = (E[]) new Object[capacity];
+ for (int i = 0; i < size; i++)
+ data[i] = (E) s.readObject();
+ }
+}