Java矢量队列Vector使用示例

Vector共有4个构造函数
// 默认构造函数
Vector()
// capacity是Vector的默认容量大小。当由于增加数据导致容量增加时，每次容量会增加一倍。
Vector(int capacity)
// capacity是Vector的默认容量大小，capacityIncrement是每次Vector容量增加时的增量值。
Vector(int capacity, int capacityIncrement)
// 创建一个包含collection的Vector
Vector(Collection<? extends E> collection) 

synchronized booleanadd(E object) void add(int location, E object)
synchronized booleanaddAll(Collection<? extends E> collection)
synchronized booleanaddAll(int location, Collection<? extends E> collection)
synchronized void addElement(E object)
synchronized intcapacity() void clear()
synchronized Object clone() booleancontains(Object object)
synchronized booleancontainsAll(Collection<?> collection)
synchronized void copyInto(Object[] elements)
synchronized EelementAt(int location) Enumeration<E> elements()
synchronized void ensureCapacity(int minimumCapacity)
synchronized booleanequals(Object object)
synchronized EfirstElement() Eget(int location)
synchronized inthashCode()
synchronized intindexOf(Object object, int location) intindexOf(Object object)
synchronized void insertElementAt(E object, int location)
synchronized booleanisEmpty()
synchronized ElastElement()
synchronized intlastIndexOf(Object object, int location)
synchronized intlastIndexOf(Object object)
synchronized Eremove(int location) booleanremove(Object object)
synchronized booleanremoveAll(Collection<?> collection)
synchronized void removeAllElements()
synchronized booleanremoveElement(Object object)
synchronized void removeElementAt(int location)
synchronized booleanretainAll(Collection<?> collection)
synchronized Eset(int location, E object)
synchronized void setElementAt(E object, int location)
synchronized void setSize(int length)
synchronized intsize()
synchronized List<E>subList(int start, int end)
synchronized <T> T[]toArray(T[] contents)
synchronized Object[] toArray()
synchronized String toString()
synchronized void trimToSize() 

java.lang.Object ↳ java.util.AbstractCollection<E> ↳ java.util.AbstractList<E> ↳ java.util.Vector<E>
public class Vector<E>extends AbstractList<E>implements List<E>, RandomAccess, Cloneable, java.io.Serializable {} 

package java.util;
public class Vector<E>extends AbstractList<E>implements List<E>, RandomAccess, Cloneable, java.io.Serializable
{ // 保存Vector中数据的数组protected Object[] elementData;// 实际数据的数量protected int elementCount;// 容量增长系数protected int capacityIncrement;// Vector的序列版本号private static final long serialVersionUID = -2767605614048989439L;// Vector构造函数。默认容量是10。public Vector() {this(10);}// 指定Vector容量大小的构造函数public Vector(int initialCapacity) {this(initialCapacity, 0);}// 指定Vector"容量大小"和"增长系数"的构造函数public Vector(int initialCapacity, int capacityIncrement) {super();if (initialCapacity < 0)throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity);// 新建一个数组，数组容量是initialCapacitythis.elementData = new Object[initialCapacity];// 设置容量增长系数this.capacityIncrement = capacityIncrement;}// 指定集合的Vector构造函数。public Vector(Collection<? extends E> c) {// 获取“集合(c)”的数组，并将其赋值给elementDataelementData = c.toArray();// 设置数组长度elementCount = elementData.length;// c.toArray might (incorrectly) not return Object[] (see 6260652)if (elementData.getClass() != Object[].class)elementData = Arrays.copyOf(elementData, elementCount, Object[].class);}// 将数组Vector的全部元素都拷贝到数组anArray中public synchronized void copyInto(Object[] anArray) {System.arraycopy(elementData, 0, anArray, 0, elementCount);}// 将当前容量值设为 =实际元素个数public synchronized void trimToSize() {modCount++;int oldCapacity = elementData.length;if (elementCount < oldCapacity) {elementData = Arrays.copyOf(elementData, elementCount);}}// 确认“Vector容量”的帮助函数private void ensureCapacityHelper(int minCapacity) {int oldCapacity = elementData.length;// 当Vector的容量不足以容纳当前的全部元素，增加容量大小。// 若 容量增量系数>0(即capacityIncrement>0)，则将容量增大当capacityIncrement// 否则，将容量增大一倍。if (minCapacity > oldCapacity) {Object[] oldData = elementData;int newCapacity = (capacityIncrement > 0) ?(oldCapacity + capacityIncrement) : (oldCapacity * 2);if (newCapacity < minCapacity) {newCapacity = minCapacity;}elementData = Arrays.copyOf(elementData, newCapacity);}}// 确定Vector的容量。public synchronized void ensureCapacity(int minCapacity) {// 将Vector的改变统计数+1modCount++;ensureCapacityHelper(minCapacity);}// 设置容量值为 newSizepublic synchronized void setSize(int newSize) {modCount++;if (newSize > elementCount) {// 若 "newSize 大于 Vector容量"，则调整Vector的大小。ensureCapacityHelper(newSize);} else {// 若 "newSize 小于/等于 Vector容量"，则将newSize位置开始的元素都设置为nullfor (int i = newSize ; i < elementCount ; i++) {elementData[i] = null;}}elementCount = newSize;}// 返回“Vector的总的容量”public synchronized int capacity() {return elementData.length;}// 返回“Vector的实际大小”，即Vector中元素个数public synchronized int size() {return elementCount;}// 判断Vector是否为空public synchronized boolean isEmpty() {return elementCount == 0;}// 返回“Vector中全部元素对应的Enumeration”public Enumeration<E> elements() {// 通过匿名类实现Enumerationreturn new Enumeration<E>() {int count = 0;// 是否存在下一个元素public boolean hasMoreElements() {return count < elementCount;}// 获取下一个元素public E nextElement() {synchronized (Vector.this) {if (count < elementCount) {return (E)elementData[count++];}}throw new NoSuchElementException("Vector Enumeration");}};}// 返回Vector中是否包含对象(o)public boolean contains(Object o) {return indexOf(o, 0) >= 0;}// 从index位置开始向后查找元素(o)。// 若找到，则返回元素的索引值；否则，返回-1public synchronized int indexOf(Object o, int index) {if (o == null) {// 若查找元素为null，则正向找出null元素，并返回它对应的序号for (int i = index ; i < elementCount ; i++)if (elementData[i]==null)return i;} else {// 若查找元素不为null，则正向找出该元素，并返回它对应的序号for (int i = index ; i < elementCount ; i++)if (o.equals(elementData[i]))return i;}return -1;}// 查找并返回元素(o)在Vector中的索引值public int indexOf(Object o) {return indexOf(o, 0);}// 从后向前查找元素(o)。并返回元素的索引public synchronized int lastIndexOf(Object o) {return lastIndexOf(o, elementCount-1);}// 从后向前查找元素(o)。开始位置是从前向后的第index个数；// 若找到，则返回元素的“索引值”；否则，返回-1。public synchronized int lastIndexOf(Object o, int index) {if (index >= elementCount)throw new IndexOutOfBoundsException(index + " >= "+ elementCount);if (o == null) {// 若查找元素为null，则反向找出null元素，并返回它对应的序号for (int i = index; i >= 0; i--)if (elementData[i]==null)return i;} else {// 若查找元素不为null，则反向找出该元素，并返回它对应的序号for (int i = index; i >= 0; i--)if (o.equals(elementData[i]))return i;}return -1;}// 返回Vector中index位置的元素。// 若index月结，则抛出异常public synchronized E elementAt(int index) {if (index >= elementCount) {throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);}return (E)elementData[index];}// 获取Vector中的第一个元素。// 若失败，则抛出异常！public synchronized E firstElement() {if (elementCount == 0) {throw new NoSuchElementException();}return (E)elementData[0];}// 获取Vector中的最后一个元素。// 若失败，则抛出异常！public synchronized E lastElement() {if (elementCount == 0) {throw new NoSuchElementException();}return (E)elementData[elementCount - 1];}// 设置index位置的元素值为objpublic synchronized void setElementAt(E obj, int index) {if (index >= elementCount) {throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);}elementData[index] = obj;}// 删除index位置的元素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 */}// 在index位置处插入元素(obj)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++;}// 将“元素obj”添加到Vector末尾public synchronized void addElement(E obj) {modCount++;ensureCapacityHelper(elementCount + 1);elementData[elementCount++] = obj;}// 在Vector中查找并删除元素obj。// 成功的话，返回true；否则，返回false。public synchronized boolean removeElement(Object obj) {modCount++;int i = indexOf(obj);if (i >= 0) {removeElementAt(i);return true;}return false;}// 删除Vector中的全部元素public synchronized void removeAllElements() {modCount++;// 将Vector中的全部元素设为nullfor (int i = 0; i < elementCount; i++)elementData[i] = null;elementCount = 0;}// 克隆函数public synchronized Object clone() {try {Vector<E> v = (Vector<E>) super.clone();// 将当前Vector的全部元素拷贝到v中v.elementData = Arrays.copyOf(elementData, elementCount);v.modCount = 0;return v;} catch (CloneNotSupportedException e) {// this shouldn't happen, since we are Cloneablethrow new InternalError();}}// 返回Object数组public synchronized Object[] toArray() {return Arrays.copyOf(elementData, elementCount);}// 返回Vector的模板数组。所谓模板数组，即可以将T设为任意的数据类型public synchronized <T> T[] toArray(T[] a) {// 若数组a的大小 < Vector的元素个数；// 则新建一个T[]数组，数组大小是“Vector的元素个数”，并将“Vector”全部拷贝到新数组中if (a.length < elementCount)return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass());// 若数组a的大小 >= Vector的元素个数；// 则将Vector的全部元素都拷贝到数组a中。System.arraycopy(elementData, 0, a, 0, elementCount);if (a.length > elementCount)a[elementCount] = null;return a;}// 获取index位置的元素public synchronized E get(int index) {if (index >= elementCount)throw new ArrayIndexOutOfBoundsException(index);return (E)elementData[index];}// 设置index位置的值为element。并返回index位置的原始值public synchronized E set(int index, E element) {if (index >= elementCount)throw new ArrayIndexOutOfBoundsException(index);Object oldValue = elementData[index];elementData[index] = element;return (E)oldValue;}// 将“元素e”添加到Vector最后。public synchronized boolean add(E e) {modCount++;ensureCapacityHelper(elementCount + 1);elementData[elementCount++] = e;return true;}// 删除Vector中的元素opublic boolean remove(Object o) {return removeElement(o);}// 在index位置添加元素elementpublic void add(int index, E element) {insertElementAt(element, index);}// 删除index位置的元素，并返回index位置的原始值public synchronized E remove(int index) {modCount++;if (index >= elementCount)throw new ArrayIndexOutOfBoundsException(index);Object 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 workreturn (E)oldValue;}// 清空Vectorpublic void clear() {removeAllElements();}// 返回Vector是否包含集合cpublic synchronized boolean containsAll(Collection<?> c) {return super.containsAll(c);}// 将集合c添加到Vector中public synchronized boolean addAll(Collection<? extends E> c) {modCount++;Object[] a = c.toArray();int numNew = a.length;ensureCapacityHelper(elementCount + numNew);// 将集合c的全部元素拷贝到数组elementData中System.arraycopy(a, 0, elementData, elementCount, numNew);elementCount += numNew;return numNew != 0;}// 删除集合c的全部元素public synchronized boolean removeAll(Collection<?> c) {return super.removeAll(c);}// 删除“非集合c中的元素”public synchronized boolean retainAll(Collection<?> c){return super.retainAll(c);}// 从index位置开始，将集合c添加到Vector中public synchronized boolean addAll(int index, Collection<? extends E> c) {modCount++;if (index < 0 || index > elementCount)throw new ArrayIndexOutOfBoundsException(index);Object[] a = c.toArray();int numNew = a.length;ensureCapacityHelper(elementCount + numNew);int numMoved = elementCount - index;if (numMoved > 0)System.arraycopy(elementData, index, elementData, index + numNew, numMoved);System.arraycopy(a, 0, elementData, index, numNew);elementCount += numNew;return numNew != 0;}// 返回两个对象是否相等public synchronized boolean equals(Object o) {return super.equals(o);}// 计算哈希值public synchronized int hashCode() {return super.hashCode();}// 调用父类的toString()public synchronized String toString() {return super.toString();}// 获取Vector中fromIndex(包括)到toIndex(不包括)的子集public synchronized List<E> subList(int fromIndex, int toIndex) {return Collections.synchronizedList(super.subList(fromIndex, toIndex), this);}// 删除Vector中fromIndex到toIndex的元素protected synchronized void removeRange(int fromIndex, int toIndex) {modCount++;int numMoved = elementCount - toIndex;System.arraycopy(elementData, toIndex, elementData, fromIndex, numMoved);// Let gc do its workint newElementCount = elementCount - (toIndex-fromIndex);while (elementCount != newElementCount)elementData[--elementCount] = null;}// java.io.Serializable的写入函数private synchronized void writeObject(java.io.ObjectOutputStream s)throws java.io.IOException {s.defaultWriteObject();}
} 

Integer value = null;
int size = vec.size();
for (int i=0; i<size; i++) {value = (Integer)vec.get(i); 
} 

Integer value = null;
int size = vec.size();
for (int i=0; i<size; i++) {value = (Integer)vec.get(i); 
} 

Integer value = null;
for (Integer integ:vec) {value = integ;
} 

Integer value = null;
Enumeration enu = vec.elements();
while (enu.hasMoreElements()) {value = (Integer)enu.nextElement();
} 

import java.util.*;
/*
 * @desc Vector遍历方式和效率的测试程序。
 *
 * @author skywang
 */
public class VectorRandomAccessTest {public static void main(String[] args) {Vector vec= new Vector();for (int i=0; i<100000; i++)vec.add(i);iteratorThroughRandomAccess(vec) ;iteratorThroughIterator(vec) ;iteratorThroughFor2(vec) ;iteratorThroughEnumeration(vec) ;}private static void isRandomAccessSupported(List list) {if (list instanceof RandomAccess) {System.out.println("RandomAccess implemented!");} else {System.out.println("RandomAccess not implemented!");}}public static void iteratorThroughRandomAccess(List list) {long startTime;long endTime;startTime = System.currentTimeMillis();for (int i=0; i<list.size(); i++) {list.get(i);}endTime = System.currentTimeMillis();long interval = endTime - startTime;System.out.println("iteratorThroughRandomAccess：" + interval+" ms");}public static void iteratorThroughIterator(List list) {long startTime;long endTime;startTime = System.currentTimeMillis();for(Iterator iter = list.iterator(); iter.hasNext(); ) {iter.next();}endTime = System.currentTimeMillis();long interval = endTime - startTime;System.out.println("iteratorThroughIterator：" + interval+" ms");}public static void iteratorThroughFor2(List list) {long startTime;long endTime;startTime = System.currentTimeMillis();for(Object obj:list);endTime = System.currentTimeMillis();long interval = endTime - startTime;System.out.println("iteratorThroughFor2：" + interval+" ms");}public static void iteratorThroughEnumeration(Vector vec) {long startTime;long endTime;startTime = System.currentTimeMillis();for(Enumeration enu = vec.elements(); enu.hasMoreElements(); ) {enu.nextElement();}endTime = System.currentTimeMillis();long interval = endTime - startTime;System.out.println("iteratorThroughEnumeration：" + interval+" ms");}
} 

import java.util.Vector;
import java.util.List;
import java.util.Iterator;
import java.util.Enumeration;
/**
 * @desc Vector测试函数：遍历Vector和常用API 
 */
public class VectorTest {public static void main(String[] args) {// 新建VectorVector vec = new Vector();// 添加元素vec.add("1");vec.add("2");vec.add("3");vec.add("4");vec.add("5");// 设置第一个元素为100vec.set(0, "100");// 将“500”插入到第3个位置vec.add(2, "300");System.out.println("vec:"+vec);// (顺序查找)获取100的索引System.out.println("vec.indexOf(100):"+vec.indexOf("100"));// (倒序查找)获取100的索引System.out.println("vec.lastIndexOf(100):"+vec.lastIndexOf("100"));// 获取第一个元素System.out.println("vec.firstElement():"+vec.firstElement());// 获取第3个元素System.out.println("vec.elementAt(2):"+vec.elementAt(2));// 获取最后一个元素System.out.println("vec.lastElement():"+vec.lastElement());// 获取Vector的大小System.out.println("size:"+vec.size());// 获取Vector的总的容量System.out.println("capacity:"+vec.capacity());// 获取vector的“第2”到“第4”个元素System.out.println("vec 2 to 4:"+vec.subList(1, 4));// 通过Enumeration遍历VectorEnumeration enu = vec.elements();while(enu.hasMoreElements())System.out.println("nextElement():"+enu.nextElement());Vector retainVec = new Vector();retainVec.add("100");retainVec.add("300");// 获取“vec”中包含在“retainVec中的元素”的集合System.out.println("vec.retain():"+vec.retainAll(retainVec));System.out.println("vec:"+vec);// 获取vec对应的String数组String[] arr = (String[]) vec.toArray(new String[0]);for (String str:arr)System.out.println("str:"+str);// 清空Vector。clear()和removeAllElements()一样！vec.clear();
//vec.removeAllElements();// 判断Vector是否为空System.out.println("vec.isEmpty():"+vec.isEmpty());} 
}