File	Doc	Category	Size	Date	Package
Vector.java	API Doc	Java SE 5 API	38152	Fri Aug 26 14:57:24 BST 2005	java.util

Vector

• java.lang.Object
  • java.util.AbstractCollection
    • java.util.AbstractList

Fields Summary
protected Object[]	elementData 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. Any array elements following the last element in the Vector are null.
protected int	elementCount The number of valid components in this Vector object. Components elementData[0] through elementData[elementCount-1] are the actual items.
protected int	capacityIncrement 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.
private static final long	serialVersionUID use serialVersionUID from JDK 1.0.2 for interoperability

Constructors Summary
public Vector(int initialCapacity, int capacityIncrement) 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. exception IllegalArgumentException if the specified initial capacity is negative super(); if (initialCapacity < 0) throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity); this.elementData = new Object[initialCapacity]; this.capacityIncrement = capacityIncrement;
public Vector(int initialCapacity) 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. exception IllegalArgumentException if the specified initial capacity is negative this(initialCapacity, 0);
public Vector() Constructs an empty vector so that its internal data array has size 10 and its standard capacity increment is zero. this(10);
public Vector(Collection c) 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 elementCount = c.size(); // 10% for growth elementData = new Object[ (int)Math.min((elementCount*110L)/100,Integer.MAX_VALUE)]; c.toArray(elementData);

Methods Summary
public synchronized boolean	add(E o) Appends the specified element to the end of this Vector. param o element to be appended to this Vector. return true (as per the general contract of Collection.add). since 1.2 modCount++; ensureCapacityHelper(elementCount + 1); elementData[elementCount++] = o; return true;
public void	add(int index, E element) 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. exception ArrayIndexOutOfBoundsException index is out of range (index < 0 || index > size()). since 1.2 insertElementAt(element, index);
public synchronized boolean	addAll(java.util.Collection 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 true if this Vector changed as a result of the call. throws NullPointerException if the specified collection is null. since 1.2 modCount++; Object[] a = c.toArray(); int numNew = a.length; ensureCapacityHelper(elementCount + numNew); System.arraycopy(a, 0, elementData, elementCount, numNew); elementCount += numNew; return numNew != 0;
public synchronized boolean	addAll(int index, java.util.Collection c) 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 first element from the specified collection. param c elements to be inserted into this Vector. return true if this Vector changed as a result of the call. exception ArrayIndexOutOfBoundsException index out of range (index < 0 || index > size()). throws NullPointerException if the specified collection is null. since 1.2 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;
public synchronized void	addElement(E obj) 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. This method is identical in functionality to the add(Object) method (which is part of the List interface). param obj the component to be added. see #add(Object) see List modCount++; ensureCapacityHelper(elementCount + 1); elementData[elementCount++] = obj;
public synchronized int	capacity() Returns the current capacity of this vector. return the current capacity (the length of its internal data array, kept in the field elementData of this vector). return elementData.length;
public void	clear() 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 removeAllElements();
public synchronized java.lang.Object	clone() 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 Vector object. return a clone of this vector. try { Vector<E> v = (Vector<E>) super.clone(); v.elementData = new Object[elementCount]; System.arraycopy(elementData, 0, v.elementData, 0, elementCount); v.modCount = 0; return v; } catch (CloneNotSupportedException e) { // this shouldn't happen, since we are Cloneable throw new InternalError(); }
public boolean	contains(java.lang.Object elem) Tests if the specified object is a component in this vector. param elem an object. return true if and only if the specified object is the same as a component in this vector, as determined by the equals method; false otherwise. return indexOf(elem, 0) >= 0;
public synchronized boolean	containsAll(java.util.Collection c) 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. return super.containsAll(c);
public synchronized void	copyInto(java.lang.Object[] anArray) Copies the components of this vector into the specified array. The item at index k in this vector is copied into component k of anArray. The array must be big enough to hold all the objects in this vector, else an IndexOutOfBoundsException is thrown. param anArray the array into which the components get copied. throws NullPointerException if the given array is null. System.arraycopy(elementData, 0, anArray, 0, elementCount);
public synchronized E	elementAt(int index) Returns the component at the specified index. This method is identical in functionality to the get method (which is part of the List interface). param index an index into this vector. return the component at the specified index. exception ArrayIndexOutOfBoundsException if the index is negative or not less than the current size of this Vector object. given. see #get(int) see List if (index >= elementCount) { throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount); } return (E)elementData[index];
public java.util.Enumeration	elements() Returns an enumeration of the components of this vector. The returned Enumeration object will generate all items in this vector. The first item generated is the item at index 0, then the item at index 1, and so on. return an enumeration of the components of this vector. see Enumeration see Iterator return new Enumeration<E>() { int count = 0; public boolean hasMoreElements() { return count < elementCount; } public E nextElement() { synchronized (Vector.this) { if (count < elementCount) { return (E)elementData[count++]; } } throw new NoSuchElementException("Vector Enumeration"); } };
public synchronized void	ensureCapacity(int minCapacity) 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. If the current capacity of this vector is less than minCapacity, then its capacity is increased by replacing its internal data array, kept in the field elementData, with a larger one. The size of the new data array will be the old size plus capacityIncrement, unless the value of 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 minCapacity, then the new capacity will be minCapacity. param minCapacity the desired minimum capacity. modCount++; ensureCapacityHelper(minCapacity);
private void	ensureCapacityHelper(int 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 java.util.Vector#ensureCapacity(int) int oldCapacity = elementData.length; if (minCapacity > oldCapacity) { Object[] oldData = elementData; int newCapacity = (capacityIncrement > 0) ? (oldCapacity + capacityIncrement) : (oldCapacity * 2); if (newCapacity < minCapacity) { newCapacity = minCapacity; } elementData = new Object[newCapacity]; System.arraycopy(oldData, 0, elementData, 0, elementCount); }
public synchronized boolean	equals(java.lang.Object o) 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 equal. (Two elements e1 and e2 are equal if (e1==null ? e2==null : e1.equals(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 return super.equals(o);
public synchronized E	firstElement() Returns the first component (the item at index 0) of this vector. return the first component of this vector. exception NoSuchElementException if this vector has no components. if (elementCount == 0) { throw new NoSuchElementException(); } return (E)elementData[0];
public synchronized E	get(int index) Returns the element at the specified position in this Vector. param index index of element to return. return object at the specified index exception ArrayIndexOutOfBoundsException index is out of range (index < 0 || index >= size()). since 1.2 if (index >= elementCount) throw new ArrayIndexOutOfBoundsException(index); return (E)elementData[index];
public synchronized int	hashCode() Returns the hash code value for this Vector. return super.hashCode();
public int	indexOf(java.lang.Object elem) Searches for the first occurence of the given argument, testing for equality using the equals method. param elem an object. return the index of the first occurrence of the argument in this vector, that is, the smallest value k such that elem.equals(elementData[k]) is true; returns -1 if the object is not found. see Object#equals(Object) return indexOf(elem, 0);
public synchronized int	indexOf(java.lang.Object elem, int index) Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method. param elem an object. param index the non-negative index to start searching from. return the index of the first occurrence of the object argument in this vector at position index or later in the vector, that is, the smallest value k such that elem.equals(elementData[k]) && (k >= index) is true; returns -1 if the object is not found. (Returns -1 if index >= the current size of this Vector.) exception IndexOutOfBoundsException if index is negative. see Object#equals(Object) if (elem == null) { for (int i = index ; i < elementCount ; i++) if (elementData[i]==null) return i; } else { for (int i = index ; i < elementCount ; i++) if (elem.equals(elementData[i])) return i; } return -1;
public synchronized void	insertElementAt(E obj, int index) Inserts the specified object as a component in this vector at the specified index. Each component in this vector with an index greater or equal to the specified index is shifted upward to have an index one greater than the value it had previously. The index must be a value greater than or equal to 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.) This method is identical in functionality to the add(Object, int) method (which is part of the List interface). Note that the 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. exception ArrayIndexOutOfBoundsException if the index was invalid. see #size() see #add(int, Object) see List 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++;
public synchronized boolean	isEmpty() Tests if this vector has no components. return true if and only if this vector has no components, that is, its size is zero; false otherwise. return elementCount == 0;
public synchronized E	lastElement() Returns the last component of the vector. return the last component of the vector, i.e., the component at index size() - 1. exception NoSuchElementException if this vector is empty. if (elementCount == 0) { throw new NoSuchElementException(); } return (E)elementData[elementCount - 1];
public synchronized int	lastIndexOf(java.lang.Object elem) Returns the index of the last occurrence of the specified object in this vector. param elem the desired component. return the index of the last occurrence of the specified object in this vector, that is, the largest value k such that elem.equals(elementData[k]) is true; returns -1 if the object is not found. return lastIndexOf(elem, elementCount-1);
public synchronized int	lastIndexOf(java.lang.Object elem, int index) Searches backwards for the specified object, starting from the specified index, and returns an index to it. param elem the desired component. param index the index to start searching from. return the index of the last occurrence of the specified object in this vector at position less than or equal to index in the vector, that is, the largest value k such that elem.equals(elementData[k]) && (k <= index) is true; -1 if the object is not found. (Returns -1 if index is negative.) exception IndexOutOfBoundsException if index is greater than or equal to the current size of this vector. if (index >= elementCount) throw new IndexOutOfBoundsException(index + " >= "+ elementCount); if (elem == null) { for (int i = index; i >= 0; i--) if (elementData[i]==null) return i; } else { for (int i = index; i >= 0; i--) if (elem.equals(elementData[i])) return i; } return -1;
public boolean	remove(java.lang.Object o) 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 (o==null ? get(i)==null : o.equals(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 return removeElement(o);
public synchronized E	remove(int 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. exception ArrayIndexOutOfBoundsException index out of range (index < 0 || index >= size()). param index the index of the element to removed. return element that was removed since 1.2 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 work return (E)oldValue;
public synchronized boolean	removeAll(java.util.Collection c) 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 NullPointerException if the specified collection is null. since 1.2 return super.removeAll(c);
public synchronized void	removeAllElements() Removes all components from this vector and sets its size to zero. This method is identical in functionality to the clear method (which is part of the List interface). see #clear see List modCount++; // Let gc do its work for (int i = 0; i < elementCount; i++) elementData[i] = null; elementCount = 0;
public synchronized boolean	removeElement(java.lang.Object 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. This method is identical in functionality to the remove(Object) method (which is part of the List interface). param obj the component to be removed. return true if the argument was a component of this vector; false otherwise. see List#remove(Object) see List modCount++; int i = indexOf(obj); if (i >= 0) { removeElementAt(i); return true; } return false;
public synchronized void	removeElementAt(int index) Deletes the component at the specified index. Each component in this vector with an index greater or equal to the specified index is shifted downward to have an index one smaller than the value it had previously. The size of this vector is decreased by 1. The index must be a value greater than or equal to 0 and less than the current size of the vector. This method is identical in functionality to the remove method (which is part of the List interface). Note that the remove method returns the old value that was stored at the specified position. param index the index of the object to remove. exception ArrayIndexOutOfBoundsException if the index was invalid. see #size() see #remove(int) see List 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 */
protected synchronized void	removeRange(int fromIndex, int toIndex) Removes from this List all of the elements whose index is between fromIndex, inclusive and toIndex, exclusive. Shifts any succeeding elements to the left (reduces their index). This call shortens the ArrayList by (toIndex - fromIndex) elements. (If toIndex==fromIndex, this operation has no effect.) param fromIndex index of first element to be removed. param toIndex index after last element to be removed. modCount++; int numMoved = elementCount - toIndex; System.arraycopy(elementData, toIndex, elementData, fromIndex, numMoved); // Let gc do its work int newElementCount = elementCount - (toIndex-fromIndex); while (elementCount != newElementCount) elementData[--elementCount] = null;
public synchronized boolean	retainAll(java.util.Collection c) 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 NullPointerException if the specified collection is null. since 1.2 return super.retainAll(c);
public synchronized E	set(int index, E element) Replaces the element at the specified position in this Vector with the specified element. param index index of element to replace. param element element to be stored at the specified position. return the element previously at the specified position. exception ArrayIndexOutOfBoundsException index out of range (index < 0 || index >= size()). since 1.2 if (index >= elementCount) throw new ArrayIndexOutOfBoundsException(index); Object oldValue = elementData[index]; elementData[index] = element; return (E)oldValue;
public synchronized void	setElementAt(E obj, int index) Sets the component at the specified index of this vector to be the specified object. The previous component at that position is discarded. The index must be a value greater than or equal to 0 and less than the current size of the vector. This method is identical in functionality to the set method (which is part of the List interface). Note that the set method reverses the order of the parameters, to more closely match array usage. Note also that the 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. exception ArrayIndexOutOfBoundsException if the index was invalid. see #size() see List see #set(int, java.lang.Object) if (index >= elementCount) { throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount); } elementData[index] = obj;
public synchronized void	setSize(int newSize) Sets the size of this vector. If the new size is greater than the current size, new null items are added to the end of the vector. If the new size is less than the current size, all components at index newSize and greater are discarded. param newSize the new size of this vector. throws ArrayIndexOutOfBoundsException if new size is negative. modCount++; if (newSize > elementCount) { ensureCapacityHelper(newSize); } else { for (int i = newSize ; i < elementCount ; i++) { elementData[i] = null; } } elementCount = newSize;
public synchronized int	size() Returns the number of components in this vector. return the number of components in this vector. return elementCount;
public synchronized java.util.List	subList(int fromIndex, int toIndex) 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. 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: list.subList(from, to).clear(); Similar idioms may be constructed for indexOf and lastIndexOf, and all of the algorithms in the Collections class can be applied to a subList. The semantics of the List returned by this method become undefined if the backing list (i.e., this List) is structurally modified 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 endpoint index value out of range (fromIndex < 0 || toIndex > size) throws IllegalArgumentException endpoint indices out of order (fromIndex > toIndex) return Collections.synchronizedList(super.subList(fromIndex, toIndex), this);
public synchronized java.lang.Object[]	toArray() Returns an array containing all of the elements in this Vector in the correct order. since 1.2 Object[] result = new Object[elementCount]; System.arraycopy(elementData, 0, result, 0, elementCount); return result;
public synchronized T[]	toArray(T[] a) 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. 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 only if the caller knows that the Vector does not contain any null elements. 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. exception ArrayStoreException the runtime type of a is not a supertype of the runtime type of every element in this Vector. throws NullPointerException if the given array is null. since 1.2 if (a.length < elementCount) a = (T[])java.lang.reflect.Array.newInstance( a.getClass().getComponentType(), elementCount); System.arraycopy(elementData, 0, a, 0, elementCount); if (a.length > elementCount) a[elementCount] = null; return a;
public synchronized java.lang.String	toString() Returns a string representation of this Vector, containing the String representation of each element. return super.toString();
public synchronized void	trimToSize() 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 elementData, with a smaller one. An application can use this operation to minimize the storage of a vector. modCount++; int oldCapacity = elementData.length; if (elementCount < oldCapacity) { Object oldData[] = elementData; elementData = new Object[elementCount]; System.arraycopy(oldData, 0, elementData, 0, elementCount); }
private synchronized void	writeObject(java.io.ObjectOutputStream s) Save the state of the Vector instance to a stream (that is, serialize it). This method is present merely for synchronization. It just calls the default readObject method. s.defaultWriteObject();