Java tutorial
/* * Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.util; import java.io.IOException; import java.io.ObjectInputStream; import java.io.StreamCorruptedException; import java.util.function.Consumer; import java.util.function.Predicate; import java.util.function.UnaryOperator; import jdk.internal.util.ArraysSupport; /** * 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 id="fail-fast"> * The iterators returned by this class's {@link #iterator() iterator} and * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>: * 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</em> fail-fast; if the * Vector is structurally modified at any time after the enumeration is * created then the results of enumerating are undefined. * * <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}/java.base/java/util/package-summary.html#CollectionsFramework"> * 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}. * * @param <E> Type of component elements * * @author Lee Boynton * @author Jonathan Payne * @see Collection * @see LinkedList * @since 1.0 */ 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; // defend against c.toArray (incorrectly) not returning Object[] // (see e.g. https://bugs.openjdk.java.net/browse/JDK-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++; if (minCapacity > elementData.length) grow(minCapacity); } } /** * Increases the capacity to ensure that it can hold at least the * number of elements specified by the minimum capacity argument. * * @param minCapacity the desired minimum capacity * @throws OutOfMemoryError if minCapacity is less than zero */ private Object[] grow(int minCapacity) { int oldCapacity = elementData.length; int newCapacity = ArraysSupport.newLength(oldCapacity, minCapacity - oldCapacity, /* minimum growth */ capacityIncrement > 0 ? capacityIncrement : oldCapacity /* preferred growth */); return elementData = Arrays.copyOf(elementData, newCapacity); } private Object[] grow() { return grow(elementCount + 1); } /** * 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 > elementData.length) grow(newSize); final Object[] es = elementData; for (int to = elementCount, i = newSize; i < to; i++) es[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. If the vector is * structurally modified while enumerating over the elements then the * results of enumerating are undefined. * * @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 * {@code Objects.equals(o, 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 * {@code Objects.equals(o, 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 * {@code (i >= index && Objects.equals(o, 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 * {@code Objects.equals(o, 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 * {@code (i <= index && Objects.equals(o, 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) { 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); } modCount++; 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) { if (index > elementCount) { throw new ArrayIndexOutOfBoundsException(index + " > " + elementCount); } modCount++; final int s = elementCount; Object[] elementData = this.elementData; if (s == elementData.length) elementData = grow(); System.arraycopy(elementData, index, elementData, index + 1, s - index); elementData[index] = obj; elementCount = s + 1; } /** * 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++; add(obj, elementData, elementCount); } /** * 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() { final Object[] es = elementData; for (int to = elementCount, i = elementCount = 0; i < to; i++) es[i] = null; modCount++; } /** * 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<E>) super.clone(); v.elementData = Arrays.copyOf(elementData, elementCount); v.modCount = 0; return v; } catch (CloneNotSupportedException e) { // this shouldn't happen, since we are Cloneable throw new InternalError(e); } } /** * Returns an array containing all of the elements in this Vector * in the correct order. * * @since 1.2 */ public synchronized Object[] toArray() { return Arrays.copyOf(elementData, elementCount); } /** * Returns an array containing all of the elements in this Vector in the * correct order; the runtime type of the returned array is that of the * specified array. If the Vector fits in the specified array, it is * returned therein. Otherwise, a new array is allocated with the runtime * type of the specified array and the size of this Vector. * * <p>If the Vector fits in the specified array with room to spare * (i.e., the array has more elements than the Vector), * the element in the array immediately following the end of the * Vector is set to null. (This is useful in determining the length * of the Vector <em>only</em> if the caller knows that the Vector * does not contain any null elements.) * * @param <T> type of array elements. The same type as {@code <E>} or a * supertype of {@code <E>}. * @param a the array into which the elements of the Vector are to * be stored, if it is big enough; otherwise, a new array of the * same runtime type is allocated for this purpose. * @return an array containing the elements of the Vector * @throws ArrayStoreException if the runtime type of a, {@code <T>}, is not * a supertype of the runtime type, {@code <E>}, of every element in this * Vector * @throws NullPointerException if the given array is null * @since 1.2 */ @SuppressWarnings("unchecked") public synchronized <T> T[] toArray(T[] a) { if (a.length < elementCount) return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass()); System.arraycopy(elementData, 0, a, 0, elementCount); if (a.length > elementCount) a[elementCount] = null; return a; } // Positional Access Operations @SuppressWarnings("unchecked") E elementData(int index) { return (E) elementData[index]; } @SuppressWarnings("unchecked") static <E> E elementAt(Object[] es, int index) { return (E) es[index]; } /** * Returns the element at the specified position in this Vector. * * @param index index of the element to return * @return object at the specified index * @throws ArrayIndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index >= size()}) * @since 1.2 */ public synchronized E get(int index) { if (index >= elementCount) throw new ArrayIndexOutOfBoundsException(index); return elementData(index); } /** * Replaces the element at the specified position in this Vector with the * specified element. * * @param index index of the element to replace * @param element element to be stored at the specified position * @return the element previously at the specified position * @throws ArrayIndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index >= size()}) * @since 1.2 */ public synchronized E set(int index, E element) { if (index >= elementCount) throw new ArrayIndexOutOfBoundsException(index); E oldValue = elementData(index); elementData[index] = element; return oldValue; } /** * This helper method split out from add(E) to keep method * bytecode size under 35 (the -XX:MaxInlineSize default value), * which helps when add(E) is called in a C1-compiled loop. */ private void add(E e, Object[] elementData, int s) { if (s == elementData.length) elementData = grow(); elementData[s] = e; elementCount = s + 1; } /** * Appends the specified element to the end of this Vector. * * @param e element to be appended to this Vector * @return {@code true} (as specified by {@link Collection#add}) * @since 1.2 */ public synchronized boolean add(E e) { modCount++; add(e, elementData, elementCount); return true; } /** * Removes the first occurrence of the specified element in this Vector * If the Vector does not contain the element, it is unchanged. More * formally, removes the element with the lowest index i such that * {@code Objects.equals(o, get(i))} (if such * an element exists). * * @param o element to be removed from this Vector, if present * @return true if the Vector contained the specified element * @since 1.2 */ public boolean remove(Object o) { return removeElement(o); } /** * Inserts the specified element at the specified position in this Vector. * Shifts the element currently at that position (if any) and any * subsequent elements to the right (adds one to their indices). * * @param index index at which the specified element is to be inserted * @param element element to be inserted * @throws ArrayIndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index > size()}) * @since 1.2 */ public void add(int index, E element) { insertElementAt(element, index); } /** * Removes the element at the specified position in this Vector. * Shifts any subsequent elements to the left (subtracts one from their * indices). Returns the element that was removed from the Vector. * * @param index the index of the element to be removed * @return element that was removed * @throws ArrayIndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index >= size()}) * @since 1.2 */ public synchronized E remove(int index) { modCount++; if (index >= elementCount) throw new ArrayIndexOutOfBoundsException(index); E oldValue = elementData(index); int numMoved = elementCount - index - 1; if (numMoved > 0) System.arraycopy(elementData, index + 1, elementData, index, numMoved); elementData[--elementCount] = null; // Let gc do its work return oldValue; } /** * Removes all of the elements from this Vector. The Vector will * be empty after this call returns (unless it throws an exception). * * @since 1.2 */ public void clear() { removeAllElements(); } // Bulk Operations /** * Returns true if this Vector contains all of the elements in the * specified Collection. * * @param c a collection whose elements will be tested for containment * in this Vector * @return true if this Vector contains all of the elements in the * specified collection * @throws NullPointerException if the specified collection is null */ public synchronized boolean containsAll(Collection<?> c) { return super.containsAll(c); } /** * Appends all of the elements in the specified Collection to the end of * this Vector, 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 Vector, and this Vector is nonempty.) * * @param c elements to be inserted into this Vector * @return {@code true} if this Vector changed as a result of the call * @throws NullPointerException if the specified collection is null * @since 1.2 */ public boolean addAll(Collection<? extends E> c) { Object[] a = c.toArray(); modCount++; int numNew = a.length; if (numNew == 0) return false; synchronized (this) { Object[] elementData = this.elementData; final int s = elementCount; if (numNew > elementData.length - s) elementData = grow(s + numNew); System.arraycopy(a, 0, elementData, s, numNew); elementCount = s + numNew; return true; } } /** * Removes from this Vector all of its elements that are contained in the * specified Collection. * * @param c a collection of elements to be removed from the Vector * @return true if this Vector changed as a result of the call * @throws ClassCastException if the types of one or more elements * in this vector are incompatible with the specified * collection * (<a href="Collection.html#optional-restrictions">optional</a>) * @throws NullPointerException if this vector contains one or more null * elements and the specified collection does not support null * elements * (<a href="Collection.html#optional-restrictions">optional</a>), * or if the specified collection is null * @since 1.2 */ public boolean removeAll(Collection<?> c) { Objects.requireNonNull(c); return bulkRemove(e -> c.contains(e)); } /** * Retains only the elements in this Vector that are contained in the * specified Collection. In other words, removes from this Vector all * of its elements that are not contained in the specified Collection. * * @param c a collection of elements to be retained in this Vector * (all other elements are removed) * @return true if this Vector changed as a result of the call * @throws ClassCastException if the types of one or more elements * in this vector are incompatible with the specified * collection * (<a href="Collection.html#optional-restrictions">optional</a>) * @throws NullPointerException if this vector contains one or more null * elements and the specified collection does not support null * elements * (<a href="Collection.html#optional-restrictions">optional</a>), * or if the specified collection is null * @since 1.2 */ public boolean retainAll(Collection<?> c) { Objects.requireNonNull(c); return bulkRemove(e -> !c.contains(e)); } /** * @throws NullPointerException {@inheritDoc} */ @Override public boolean removeIf(Predicate<? super E> filter) { Objects.requireNonNull(filter); return bulkRemove(filter); } // A tiny bit set implementation private static long[] nBits(int n) { return new long[((n - 1) >> 6) + 1]; } private static void setBit(long[] bits, int i) { bits[i >> 6] |= 1L << i; } private static boolean isClear(long[] bits, int i) { return (bits[i >> 6] & (1L << i)) == 0; } private synchronized boolean bulkRemove(Predicate<? super E> filter) { int expectedModCount = modCount; final Object[] es = elementData; final int end = elementCount; int i; // Optimize for initial run of survivors for (i = 0; i < end && !filter.test(elementAt(es, i)); i++) ; // Tolerate predicates that reentrantly access the collection for // read (but writers still get CME), so traverse once to find // elements to delete, a second pass to physically expunge. if (i < end) { final int beg = i; final long[] deathRow = nBits(end - beg); deathRow[0] = 1L; // set bit 0 for (i = beg + 1; i < end; i++) if (filter.test(elementAt(es, i))) setBit(deathRow, i - beg); if (modCount != expectedModCount) throw new ConcurrentModificationException(); modCount++; int w = beg; for (i = beg; i < end; i++) if (isClear(deathRow, i - beg)) es[w++] = es[i]; for (i = elementCount = w; i < end; i++) es[i] = null; return true; } else { if (modCount != expectedModCount) throw new ConcurrentModificationException(); return false; } } /** * Inserts all of the elements in the specified Collection into this * Vector at the specified position. Shifts the element currently at * that position (if any) and any subsequent elements to the right * (increases their indices). The new elements will appear in the Vector * in the order that they are returned by the specified Collection's * iterator. * * @param index index at which to insert the first element from the * specified collection * @param c elements to be inserted into this Vector * @return {@code true} if this Vector changed as a result of the call * @throws ArrayIndexOutOfBoundsException if the index is out of range * ({@code index < 0 || index > size()}) * @throws NullPointerException if the specified collection is null * @since 1.2 */ public synchronized boolean addAll(int index, Collection<? extends E> c) { if (index < 0 || index > elementCount) throw new ArrayIndexOutOfBoundsException(index); Object[] a = c.toArray(); modCount++; int numNew = a.length; if (numNew == 0) return false; Object[] elementData = this.elementData; final int s = elementCount; if (numNew > elementData.length - s) elementData = grow(s + numNew); int numMoved = s - index; if (numMoved > 0) System.arraycopy(elementData, index, elementData, index + numNew, numMoved); System.arraycopy(a, 0, elementData, index, numNew); elementCount = s + numNew; return true; } /** * Compares the specified Object with this Vector for equality. Returns * true if and only if the specified Object is also a List, both Lists * have the same size, and all corresponding pairs of elements in the two * Lists are <em>equal</em>. (Two elements {@code e1} and * {@code e2} are <em>equal</em> if {@code Objects.equals(e1, e2)}.) * In other words, two Lists are defined to be * equal if they contain the same elements in the same order. * * @param o the Object to be compared for equality with this Vector * @return true if the specified Object is equal to this Vector */ public synchronized boolean equals(Object o) { return super.equals(o); } /** * Returns the hash code value for this Vector. */ public synchronized int hashCode() { return super.hashCode(); } /** * Returns a string representation of this Vector, containing * the String representation of each element. */ public synchronized String toString() { return super.toString(); } /** * Returns a view of the portion of this List between fromIndex, * inclusive, and toIndex, exclusive. (If fromIndex and toIndex are * equal, the returned List is empty.) The returned List is backed by this * List, so changes in the returned List are reflected in this List, and * vice-versa. The returned List supports all of the optional List * operations supported by this List. * * <p>This method eliminates the need for explicit range operations (of * the sort that commonly exist for arrays). Any operation that expects * a List can be used as a range operation by operating on a subList view * instead of a whole List. For example, the following idiom * removes a range of elements from a List: * <pre> * list.subList(from, to).clear(); * </pre> * Similar idioms may be constructed for indexOf and lastIndexOf, * and all of the algorithms in the Collections class can be applied to * a subList. * * <p>The semantics of the List returned by this method become undefined if * the backing list (i.e., this List) is <i>structurally modified</i> in * any way other than via the returned List. (Structural modifications are * those that change the size of the List, or otherwise perturb it in such * a fashion that iterations in progress may yield incorrect results.) * * @param fromIndex low endpoint (inclusive) of the subList * @param toIndex high endpoint (exclusive) of the subList * @return a view of the specified range within this List * @throws IndexOutOfBoundsException if an endpoint index value is out of range * {@code (fromIndex < 0 || toIndex > size)} * @throws IllegalArgumentException if the endpoint indices are out of order * {@code (fromIndex > toIndex)} */ public synchronized List<E> subList(int fromIndex, int toIndex) { return Collections.synchronizedList(super.subList(fromIndex, toIndex), this); } /** * Removes from this list all of the elements whose index is between * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. * Shifts any succeeding elements to the left (reduces their index). * This call shortens the list by {@code (toIndex - fromIndex)} elements. * (If {@code toIndex==fromIndex}, this operation has no effect.) */ protected synchronized void removeRange(int fromIndex, int toIndex) { modCount++; shiftTailOverGap(elementData, fromIndex, toIndex); } /** Erases the gap from lo to hi, by sliding down following elements. */ private void shiftTailOverGap(Object[] es, int lo, int hi) { System.arraycopy(es, hi, es, lo, elementCount - hi); for (int to = elementCount, i = (elementCount -= hi - lo); i < to; i++) es[i] = null; } /** * Loads a {@code Vector} instance from a stream * (that is, deserializes it). * This method performs checks to ensure the consistency * of the fields. * * @param in the stream * @throws java.io.IOException if an I/O error occurs * @throws ClassNotFoundException if the stream contains data * of a non-existing class */ private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { ObjectInputStream.GetField gfields = in.readFields(); int count = gfields.get("elementCount", 0); Object[] data = (Object[]) gfields.get("elementData", null); if (count < 0 || data == null || count > data.length) { throw new StreamCorruptedException("Inconsistent vector internals"); } elementCount = count; elementData = data.clone(); } /** * Saves the state of the {@code Vector} instance to a stream * (that is, serializes it). * This method performs synchronization to ensure the consistency * of the serialized data. * * @param s the stream * @throws java.io.IOException if an I/O error occurs */ private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { final java.io.ObjectOutputStream.PutField fields = s.putFields(); final Object[] data; synchronized (this) { fields.put("capacityIncrement", capacityIncrement); fields.put("elementCount", elementCount); data = elementData.clone(); } fields.put("elementData", data); s.writeFields(); } /** * Returns a list iterator over the elements in this list (in proper * sequence), starting at the specified position in the list. * The specified index indicates the first element that would be * returned by an initial call to {@link ListIterator#next next}. * An initial call to {@link ListIterator#previous previous} would * return the element with the specified index minus one. * * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. * * @throws IndexOutOfBoundsException {@inheritDoc} */ public synchronized ListIterator<E> listIterator(int index) { if (index < 0 || index > elementCount) throw new IndexOutOfBoundsException("Index: " + index); return new ListItr(index); } /** * Returns a list iterator over the elements in this list (in proper * sequence). * * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. * * @see #listIterator(int) */ public synchronized ListIterator<E> listIterator() { return new ListItr(0); } /** * Returns an iterator over the elements in this list in proper sequence. * * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>. * * @return an iterator over the elements in this list in proper sequence */ public synchronized Iterator<E> iterator() { return new Itr(); } /** * An optimized version of AbstractList.Itr */ private class Itr implements Iterator<E> { int cursor; // index of next element to return int lastRet = -1; // index of last element returned; -1 if no such int expectedModCount = modCount; public boolean hasNext() { // Racy but within spec, since modifications are checked // within or after synchronization in next/previous return cursor != elementCount; } public E next() { synchronized (Vector.this) { checkForComodification(); int i = cursor; if (i >= elementCount) throw new NoSuchElementException(); cursor = i + 1; return elementData(lastRet = i); } } public void remove() { if (lastRet == -1) throw new IllegalStateException(); synchronized (Vector.this) { checkForComodification(); Vector.this.remove(lastRet); expectedModCount = modCount; } cursor = lastRet; lastRet = -1; } @Override public void forEachRemaining(Consumer<? super E> action) { Objects.requireNonNull(action); synchronized (Vector.this) { final int size = elementCount; int i = cursor; if (i >= size) { return; } final Object[] es = elementData; if (i >= es.length) throw new ConcurrentModificationException(); while (i < size && modCount == expectedModCount) action.accept(elementAt(es, i++)); // update once at end of iteration to reduce heap write traffic cursor = i; lastRet = i - 1; checkForComodification(); } } final void checkForComodification() { if (modCount != expectedModCount) throw new ConcurrentModificationException(); } } /** * An optimized version of AbstractList.ListItr */ final class ListItr extends Itr implements ListIterator<E> { ListItr(int index) { super(); cursor = index; } public boolean hasPrevious() { return cursor != 0; } public int nextIndex() { return cursor; } public int previousIndex() { return cursor - 1; } public E previous() { synchronized (Vector.this) { checkForComodification(); int i = cursor - 1; if (i < 0) throw new NoSuchElementException(); cursor = i; return elementData(lastRet = i); } } public void set(E e) { if (lastRet == -1) throw new IllegalStateException(); synchronized (Vector.this) { checkForComodification(); Vector.this.set(lastRet, e); } } public void add(E e) { int i = cursor; synchronized (Vector.this) { checkForComodification(); Vector.this.add(i, e); expectedModCount = modCount; } cursor = i + 1; lastRet = -1; } } /** * @throws NullPointerException {@inheritDoc} */ @Override public synchronized void forEach(Consumer<? super E> action) { Objects.requireNonNull(action); final int expectedModCount = modCount; final Object[] es = elementData; final int size = elementCount; for (int i = 0; modCount == expectedModCount && i < size; i++) action.accept(elementAt(es, i)); if (modCount != expectedModCount) throw new ConcurrentModificationException(); } /** * @throws NullPointerException {@inheritDoc} */ @Override public synchronized void replaceAll(UnaryOperator<E> operator) { Objects.requireNonNull(operator); final int expectedModCount = modCount; final Object[] es = elementData; final int size = elementCount; for (int i = 0; modCount == expectedModCount && i < size; i++) es[i] = operator.apply(elementAt(es, i)); if (modCount != expectedModCount) throw new ConcurrentModificationException(); // TODO(8203662): remove increment of modCount from ... modCount++; } @SuppressWarnings("unchecked") @Override public synchronized void sort(Comparator<? super E> c) { final int expectedModCount = modCount; Arrays.sort((E[]) elementData, 0, elementCount, c); if (modCount != expectedModCount) throw new ConcurrentModificationException(); modCount++; } /** * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> * and <em>fail-fast</em> {@link Spliterator} over the elements in this * list. * * <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}. * Overriding implementations should document the reporting of additional * characteristic values. * * @return a {@code Spliterator} over the elements in this list * @since 1.8 */ @Override public Spliterator<E> spliterator() { return new VectorSpliterator(null, 0, -1, 0); } /** Similar to ArrayList Spliterator */ final class VectorSpliterator implements Spliterator<E> { private Object[] array; private int index; // current index, modified on advance/split private int fence; // -1 until used; then one past last index private int expectedModCount; // initialized when fence set /** Creates new spliterator covering the given range. */ VectorSpliterator(Object[] array, int origin, int fence, int expectedModCount) { this.array = array; this.index = origin; this.fence = fence; this.expectedModCount = expectedModCount; } private int getFence() { // initialize on first use int hi; if ((hi = fence) < 0) { synchronized (Vector.this) { array = elementData; expectedModCount = modCount; hi = fence = elementCount; } } return hi; } public Spliterator<E> trySplit() { int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; return (lo >= mid) ? null : new VectorSpliterator(array, lo, index = mid, expectedModCount); } @SuppressWarnings("unchecked") public boolean tryAdvance(Consumer<? super E> action) { Objects.requireNonNull(action); int i; if (getFence() > (i = index)) { index = i + 1; action.accept((E) array[i]); if (modCount != expectedModCount) throw new ConcurrentModificationException(); return true; } return false; } @SuppressWarnings("unchecked") public void forEachRemaining(Consumer<? super E> action) { Objects.requireNonNull(action); final int hi = getFence(); final Object[] a = array; int i; for (i = index, index = hi; i < hi; i++) action.accept((E) a[i]); if (modCount != expectedModCount) throw new ConcurrentModificationException(); } public long estimateSize() { return getFence() - index; } public int characteristics() { return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED; } } void checkInvariants() { // assert elementCount >= 0; // assert elementCount == elementData.length || elementData[elementCount] == null; } }