Java example source code file (Vector.java)
The Vector.java Java example source code/*
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package java.util;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.UnaryOperator;
/**
* The {@code Vector} class implements a growable array of
* objects. Like an array, it contains components that can be
* accessed using an integer index. However, the size of a
* {@code Vector} can grow or shrink as needed to accommodate
* adding and removing items after the {@code Vector} has been created.
*
* <p>Each vector tries to optimize storage management by maintaining a
* {@code capacity} and a {@code capacityIncrement}. The
* {@code capacity} is always at least as large as the vector
* size; it is usually larger because as components are added to the
* vector, the vector's storage increases in chunks the size of
* {@code capacityIncrement}. An application can increase the
* capacity of a vector before inserting a large number of
* components; this reduces the amount of incremental reallocation.
*
* <p>
* The iterators returned by this class's {@link #iterator() iterator} and
* {@link #listIterator(int) listIterator} methods are <em>fail-fast:
* if the vector is structurally modified at any time after the iterator is
* created, in any way except through the iterator's own
* {@link ListIterator#remove() remove} or
* {@link ListIterator#add(Object) add} methods, the iterator will throw a
* {@link 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. The {@link Enumeration Enumerations} returned by
* the {@link #elements() elements} method are <em>not fail-fast.
*
* <p>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 {@code ConcurrentModificationException} on a best-effort basis.
* Therefore, it would be wrong to write a program that depended on this
* exception for its correctness: <i>the fail-fast behavior of iterators
* should be used only to detect bugs.</i>
*
* <p>As of the Java 2 platform v1.2, this class was retrofitted to
* implement the {@link List} interface, making it a member of the
* <a href="{@docRoot}/../technotes/guides/collections/index.html">
* Java Collections Framework</a>. Unlike the new collection
* implementations, {@code Vector} is synchronized. If a thread-safe
* implementation is not needed, it is recommended to use {@link
* ArrayList} in place of {@code Vector}.
*
* @author Lee Boynton
* @author Jonathan Payne
* @see Collection
* @see LinkedList
* @since JDK1.0
*/
public class Vector<E>
extends AbstractList<E>
implements List<E>, RandomAccess, Cloneable, java.io.Serializable
{
/**
* The array buffer into which the components of the vector are
* stored. The capacity of the vector is the length of this array buffer,
* and is at least large enough to contain all the vector's elements.
*
* <p>Any array elements following the last element in the Vector are null.
*
* @serial
*/
protected Object[] elementData;
/**
* The number of valid components in this {@code Vector} object.
* Components {@code elementData[0]} through
* {@code elementData[elementCount-1]} are the actual items.
*
* @serial
*/
protected int elementCount;
/**
* The amount by which the capacity of the vector is automatically
* incremented when its size becomes greater than its capacity. If
* the capacity increment is less than or equal to zero, the capacity
* of the vector is doubled each time it needs to grow.
*
* @serial
*/
protected int capacityIncrement;
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = -2767605614048989439L;
/**
* Constructs an empty vector with the specified initial capacity and
* capacity increment.
*
* @param initialCapacity the initial capacity of the vector
* @param capacityIncrement the amount by which the capacity is
* increased when the vector overflows
* @throws IllegalArgumentException if the specified initial capacity
* is negative
*/
public Vector(int initialCapacity, int capacityIncrement) {
super();
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
this.elementData = new Object[initialCapacity];
this.capacityIncrement = capacityIncrement;
}
/**
* Constructs an empty vector with the specified initial capacity and
* with its capacity increment equal to zero.
*
* @param initialCapacity the initial capacity of the vector
* @throws IllegalArgumentException if the specified initial capacity
* is negative
*/
public Vector(int initialCapacity) {
this(initialCapacity, 0);
}
/**
* Constructs an empty vector so that its internal data array
* has size {@code 10} and its standard capacity increment is
* zero.
*/
public Vector() {
this(10);
}
/**
* Constructs a vector containing the elements of the specified
* collection, in the order they are returned by the collection's
* iterator.
*
* @param c the collection whose elements are to be placed into this
* vector
* @throws NullPointerException if the specified collection is null
* @since 1.2
*/
public Vector(Collection<? extends E> c) {
elementData = c.toArray();
elementCount = elementData.length;
// c.toArray might (incorrectly) not return Object[] (see 6260652)
if (elementData.getClass() != Object[].class)
elementData = Arrays.copyOf(elementData, elementCount, Object[].class);
}
/**
* Copies the components of this vector into the specified array.
* The item at index {@code k} in this vector is copied into
* component {@code k} of {@code anArray}.
*
* @param anArray the array into which the components get copied
* @throws NullPointerException if the given array is null
* @throws IndexOutOfBoundsException if the specified array is not
* large enough to hold all the components of this vector
* @throws ArrayStoreException if a component of this vector is not of
* a runtime type that can be stored in the specified array
* @see #toArray(Object[])
*/
public synchronized void copyInto(Object[] anArray) {
System.arraycopy(elementData, 0, anArray, 0, elementCount);
}
/**
* Trims the capacity of this vector to be the vector's current
* size. If the capacity of this vector is larger than its current
* size, then the capacity is changed to equal the size by replacing
* its internal data array, kept in the field {@code elementData},
* with a smaller one. An application can use this operation to
* minimize the storage of a vector.
*/
public synchronized void trimToSize() {
modCount++;
int oldCapacity = elementData.length;
if (elementCount < oldCapacity) {
elementData = Arrays.copyOf(elementData, elementCount);
}
}
/**
* Increases the capacity of this vector, if necessary, to ensure
* that it can hold at least the number of components specified by
* the minimum capacity argument.
*
* <p>If the current capacity of this vector is less than
* {@code minCapacity}, then its capacity is increased by replacing its
* internal data array, kept in the field {@code elementData}, with a
* larger one. The size of the new data array will be the old size plus
* {@code capacityIncrement}, unless the value of
* {@code capacityIncrement} is less than or equal to zero, in which case
* the new capacity will be twice the old capacity; but if this new size
* is still smaller than {@code minCapacity}, then the new capacity will
* be {@code minCapacity}.
*
* @param minCapacity the desired minimum capacity
*/
public synchronized void ensureCapacity(int minCapacity) {
if (minCapacity > 0) {
modCount++;
ensureCapacityHelper(minCapacity);
}
}
/**
* This implements the unsynchronized semantics of ensureCapacity.
* Synchronized methods in this class can internally call this
* method for ensuring capacity without incurring the cost of an
* extra synchronization.
*
* @see #ensureCapacity(int)
*/
private void ensureCapacityHelper(int minCapacity) {
// overflow-conscious code
if (minCapacity - elementData.length > 0)
grow(minCapacity);
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
private void grow(int minCapacity) {
// overflow-conscious code
int oldCapacity = elementData.length;
int newCapacity = oldCapacity + ((capacityIncrement > 0) ?
capacityIncrement : oldCapacity);
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
if (newCapacity - MAX_ARRAY_SIZE > 0)
newCapacity = hugeCapacity(minCapacity);
elementData = Arrays.copyOf(elementData, newCapacity);
}
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
}
/**
* Sets the size of this vector. If the new size is greater than the
* current size, new {@code null} items are added to the end of
* the vector. If the new size is less than the current size, all
* components at index {@code newSize} and greater are discarded.
*
* @param newSize the new size of this vector
* @throws ArrayIndexOutOfBoundsException if the new size is negative
*/
public synchronized void setSize(int newSize) {
modCount++;
if (newSize > elementCount) {
ensureCapacityHelper(newSize);
} else {
for (int i = newSize ; i < elementCount ; i++) {
elementData[i] = null;
}
}
elementCount = newSize;
}
/**
* Returns the current capacity of this vector.
*
* @return the current capacity (the length of its internal
* data array, kept in the field {@code elementData}
* of this vector)
*/
public synchronized int capacity() {
return elementData.length;
}
/**
* Returns the number of components in this vector.
*
* @return the number of components in this vector
*/
public synchronized int size() {
return elementCount;
}
/**
* Tests if this vector has no components.
*
* @return {@code true} if and only if this vector has
* no components, that is, its size is zero;
* {@code false} otherwise.
*/
public synchronized boolean isEmpty() {
return elementCount == 0;
}
/**
* Returns an enumeration of the components of this vector. The
* returned {@code Enumeration} object will generate all items in
* this vector. The first item generated is the item at index {@code 0},
* then the item at index {@code 1}, and so on.
*
* @return an enumeration of the components of this vector
* @see Iterator
*/
public Enumeration<E> elements() {
return new Enumeration<E>() {
int count = 0;
public boolean hasMoreElements() {
return count < elementCount;
}
public E nextElement() {
synchronized (Vector.this) {
if (count < elementCount) {
return elementData(count++);
}
}
throw new NoSuchElementException("Vector Enumeration");
}
};
}
/**
* Returns {@code true} if this vector contains the specified element.
* More formally, returns {@code true} if and only if this vector
* contains at least one element {@code e} such that
* <tt>(o==null ? e==null : o.equals(e)).
*
* @param o element whose presence in this vector is to be tested
* @return {@code true} if this vector contains the specified element
*/
public boolean contains(Object o) {
return indexOf(o, 0) >= 0;
}
/**
* Returns the index of the first occurrence of the specified element
* in this vector, or -1 if this vector does not contain the element.
* More formally, returns the lowest index {@code i} such that
* <tt>(o==null ? get(i)==null : o.equals(get(i))),
* or -1 if there is no such index.
*
* @param o element to search for
* @return the index of the first occurrence of the specified element in
* this vector, or -1 if this vector does not contain the element
*/
public int indexOf(Object o) {
return indexOf(o, 0);
}
/**
* Returns the index of the first occurrence of the specified element in
* this vector, searching forwards from {@code index}, or returns -1 if
* the element is not found.
* More formally, returns the lowest index {@code i} such that
* <tt>(i >= index && (o==null ? get(i)==null : o.equals(get(i)))),
* or -1 if there is no such index.
*
* @param o element to search for
* @param index index to start searching from
* @return the index of the first occurrence of the element in
* this vector at position {@code index} or later in the vector;
* {@code -1} if the element is not found.
* @throws IndexOutOfBoundsException if the specified index is negative
* @see Object#equals(Object)
*/
public synchronized int indexOf(Object o, int index) {
if (o == null) {
for (int i = index ; i < elementCount ; i++)
if (elementData[i]==null)
return i;
} else {
for (int i = index ; i < elementCount ; i++)
if (o.equals(elementData[i]))
return i;
}
return -1;
}
/**
* Returns the index of the last occurrence of the specified element
* in this vector, or -1 if this vector does not contain the element.
* More formally, returns the highest index {@code i} such that
* <tt>(o==null ? get(i)==null : o.equals(get(i))),
* or -1 if there is no such index.
*
* @param o element to search for
* @return the index of the last occurrence of the specified element in
* this vector, or -1 if this vector does not contain the element
*/
public synchronized int lastIndexOf(Object o) {
return lastIndexOf(o, elementCount-1);
}
/**
* Returns the index of the last occurrence of the specified element in
* this vector, searching backwards from {@code index}, or returns -1 if
* the element is not found.
* More formally, returns the highest index {@code i} such that
* <tt>(i <= index && (o==null ? get(i)==null : o.equals(get(i)))),
* or -1 if there is no such index.
*
* @param o element to search for
* @param index index to start searching backwards from
* @return the index of the last occurrence of the element at position
* less than or equal to {@code index} in this vector;
* -1 if the element is not found.
* @throws IndexOutOfBoundsException if the specified index is greater
* than or equal to the current size of this vector
*/
public synchronized int lastIndexOf(Object o, int index) {
if (index >= elementCount)
throw new IndexOutOfBoundsException(index + " >= "+ elementCount);
if (o == null) {
for (int i = index; i >= 0; i--)
if (elementData[i]==null)
return i;
} else {
for (int i = index; i >= 0; i--)
if (o.equals(elementData[i]))
return i;
}
return -1;
}
/**
* Returns the component at the specified index.
*
* <p>This method is identical in functionality to the {@link #get(int)}
* method (which is part of the {@link List} interface).
*
* @param index an index into this vector
* @return the component at the specified index
* @throws ArrayIndexOutOfBoundsException if the index is out of range
* ({@code index < 0 || index >= size()})
*/
public synchronized E elementAt(int index) {
if (index >= elementCount) {
throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
}
return elementData(index);
}
/**
* Returns the first component (the item at index {@code 0}) of
* this vector.
*
* @return the first component of this vector
* @throws NoSuchElementException if this vector has no components
*/
public synchronized E firstElement() {
if (elementCount == 0) {
throw new NoSuchElementException();
}
return elementData(0);
}
/**
* Returns the last component of the vector.
*
* @return the last component of the vector, i.e., the component at index
* <code>size() - 1.
* @throws NoSuchElementException if this vector is empty
*/
public synchronized E lastElement() {
if (elementCount == 0) {
throw new NoSuchElementException();
}
return elementData(elementCount - 1);
}
/**
* Sets the component at the specified {@code index} of this
* vector to be the specified object. The previous component at that
* position is discarded.
*
* <p>The index must be a value greater than or equal to {@code 0}
* and less than the current size of the vector.
*
* <p>This method is identical in functionality to the
* {@link #set(int, Object) set(int, E)}
* method (which is part of the {@link List} interface). Note that the
* {@code set} method reverses the order of the parameters, to more closely
* match array usage. Note also that the {@code set} method returns the
* old value that was stored at the specified position.
*
* @param obj what the component is to be set to
* @param index the specified index
* @throws ArrayIndexOutOfBoundsException if the index is out of range
* ({@code index < 0 || index >= size()})
*/
public synchronized void setElementAt(E obj, int index) {
if (index >= elementCount) {
throw new ArrayIndexOutOfBoundsException(index + " >= " +
elementCount);
}
elementData[index] = obj;
}
/**
* Deletes the component at the specified index. Each component in
* this vector with an index greater or equal to the specified
* {@code index} is shifted downward to have an index one
* smaller than the value it had previously. The size of this vector
* is decreased by {@code 1}.
*
* <p>The index must be a value greater than or equal to {@code 0}
* and less than the current size of the vector.
*
* <p>This method is identical in functionality to the {@link #remove(int)}
* method (which is part of the {@link List} interface). Note that the
* {@code remove} method returns the old value that was stored at the
* specified position.
*
* @param index the index of the object to remove
* @throws ArrayIndexOutOfBoundsException if the index is out of range
* ({@code index < 0 || index >= size()})
*/
public synchronized void removeElementAt(int index) {
modCount++;
if (index >= elementCount) {
throw new ArrayIndexOutOfBoundsException(index + " >= " +
elementCount);
}
else if (index < 0) {
throw new ArrayIndexOutOfBoundsException(index);
}
int j = elementCount - index - 1;
if (j > 0) {
System.arraycopy(elementData, index + 1, elementData, index, j);
}
elementCount--;
elementData[elementCount] = null; /* to let gc do its work */
}
/**
* Inserts the specified object as a component in this vector at the
* specified {@code index}. Each component in this vector with
* an index greater or equal to the specified {@code index} is
* shifted upward to have an index one greater than the value it had
* previously.
*
* <p>The index must be a value greater than or equal to {@code 0}
* and less than or equal to the current size of the vector. (If the
* index is equal to the current size of the vector, the new element
* is appended to the Vector.)
*
* <p>This method is identical in functionality to the
* {@link #add(int, Object) add(int, E)}
* method (which is part of the {@link List} interface). Note that the
* {@code add} method reverses the order of the parameters, to more closely
* match array usage.
*
* @param obj the component to insert
* @param index where to insert the new component
* @throws ArrayIndexOutOfBoundsException if the index is out of range
* ({@code index < 0 || index > size()})
*/
public synchronized void insertElementAt(E obj, int index) {
modCount++;
if (index > elementCount) {
throw new ArrayIndexOutOfBoundsException(index
+ " > " + elementCount);
}
ensureCapacityHelper(elementCount + 1);
System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
elementData[index] = obj;
elementCount++;
}
/**
* Adds the specified component to the end of this vector,
* increasing its size by one. The capacity of this vector is
* increased if its size becomes greater than its capacity.
*
* <p>This method is identical in functionality to the
* {@link #add(Object) add(E)}
* method (which is part of the {@link List} interface).
*
* @param obj the component to be added
*/
public synchronized void addElement(E obj) {
modCount++;
ensureCapacityHelper(elementCount + 1);
elementData[elementCount++] = obj;
}
/**
* Removes the first (lowest-indexed) occurrence of the argument
* from this vector. If the object is found in this vector, each
* component in the vector with an index greater or equal to the
* object's index is shifted downward to have an index one smaller
* than the value it had previously.
*
* <p>This method is identical in functionality to the
* {@link #remove(Object)} method (which is part of the
* {@link List} interface).
*
* @param obj the component to be removed
* @return {@code true} if the argument was a component of this
* vector; {@code false} otherwise.
*/
public synchronized boolean removeElement(Object obj) {
modCount++;
int i = indexOf(obj);
if (i >= 0) {
removeElementAt(i);
return true;
}
return false;
}
/**
* Removes all components from this vector and sets its size to zero.
*
* <p>This method is identical in functionality to the {@link #clear}
* method (which is part of the {@link List} interface).
*/
public synchronized void removeAllElements() {
modCount++;
// Let gc do its work
for (int i = 0; i < elementCount; i++)
elementData[i] = null;
elementCount = 0;
}
/**
* Returns a clone of this vector. The copy will contain a
* reference to a clone of the internal data array, not a reference
* to the original internal data array of this {@code Vector} object.
*
* @return a clone of this vector
*/
public synchronized Object clone() {
try {
@SuppressWarnings("unchecked")
Vector<E> v = (Vector
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