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Class java.util.Vector

java.lang.Object
|
   +----java.util.Vector

public class Vector

extends Object

implements Cloneable

Each vector tries to optimize storage management by maintaining a capacity and a capacityIncrement. The capacity is always at least as large as the vector size; it is usually larger because as elements are added to the vector, the vector's storage increases in chunks the size of capacityIncrement. Setting the capacity to what you want before inserting a large number of objects will reduce the amount of incremental reallocation. You can safely ignore the capacity and the vector will still work correctly.

capacityIncrement

The size of the increment.

elementCount

The number of elements in the buffer.

elementData

The buffer where elements are stored.

Vector()

Constructs an empty vector.

Vector(int)

Constructs an empty vector with the specified storage capacity.

Vector(int, int)

Constructs an empty vector with the specified storage capacity and the specified capacityIncrement.

addElement(Object)

Adds the specified object as the last element of the vector.

capacity()

Returns the current capacity of the vector.

clone()

Clones this vector.

contains(Object)

Returns true if the specified object is a value of the collection.

copyInto(Object[])

Copies the elements of this vector into the specified array.

elementAt(int)

Returns the element at the specified index.

elements()

Returns an enumeration of the elements.

ensureCapacity(int)

Ensures that the vector has at least the specified capacity.

firstElement()

Returns the first element of the sequence.

indexOf(Object)

Searches for the specified object, starting from the first position and returns an index to it.

indexOf(Object, int)

Searches for the specified object, starting at the specified position and returns an index to it.

insertElementAt(Object, int)

Inserts the specified object as an element at the specified index.

isEmpty()

Returns true if the collection contains no values.

lastElement()

Returns the last element of the sequence.

lastIndexOf(Object)

Searches backwards for the specified object, starting from the last position and returns an index to it.

lastIndexOf(Object, int)

Searches backwards for the specified object, starting from the specified position and returns an index to it.

removeAllElements()

Removes all elements of the vector.

removeElement(Object)

Removes the element from the vector.

removeElementAt(int)

Deletes the element at the specified index.

setElementAt(Object, int)

Sets the element at the specified index to be the specified object.

setSize(int)

Sets the size of the vector.

size()

Returns the number of elements in the vector.

toString()

Converts the vector to a string.

trimToSize()

Trims the vector's capacity down to size.

protected Object elementData[]

The buffer where elements are stored.

protected int elementCount

The number of elements in the buffer.

protected int capacityIncrement

The size of the increment. If it is 0 the size of the the buffer is doubled everytime it needs to grow.

public Vector(int initialCapacity,
                int capacityIncrement)

Constructs an empty vector with the specified storage capacity and the specified capacityIncrement.

Parameters:

initialCapacity - the initial storage capacity of the vector

capacityIncrement - how much to increase the element's size by.

public Vector(int initialCapacity)

Constructs an empty vector with the specified storage capacity.

Parameters:

initialCapacity - the initial storage capacity of the vector

public Vector()

Constructs an empty vector.

public final synchronized void copyInto(Object anArray[])

Copies the elements of this vector into the specified array.

Parameters:

anArray - the array where elements get copied into

public final synchronized void trimToSize()

Trims the vector's capacity down to size. Use this operation to minimize the storage of a vector. Subsequent insertions will cause reallocation.

public final synchronized void ensureCapacity(int minCapacity)

Ensures that the vector has at least the specified capacity.

Parameters:

minCapacity - the desired minimum capacity

public final synchronized void setSize(int newSize)

Sets the size of the vector. If the size shrinks, the extra elements (at the end of the vector) are lost; if the size increases, the new elements are set to null.

Parameters:

newSize - the new size of the vector

public final int capacity()

Returns the current capacity of the vector.

public final int size()

Returns the number of elements in the vector. Note that this is not the same as the vector's capacity.

public final boolean isEmpty()

Returns true if the collection contains no values.

public final synchronized Enumeration elements()

Returns an enumeration of the elements. Use the Enumeration methods on the returned object to fetch the elements sequentially.

public final boolean contains(Object elem)

Returns true if the specified object is a value of the collection.

Parameters:

elem - the desired element

public final int indexOf(Object elem)

Searches for the specified object, starting from the first position and returns an index to it.

Parameters:

elem - the desired element

Returns:

the index of the element, or -1 if it was not found.

public final synchronized int indexOf(Object elem,
                                        int index)

Searches for the specified object, starting at the specified position and returns an index to it.

Parameters:

elem - the desired element

index - the index where to start searching

Returns:

the index of the element, or -1 if it was not found.

public final int lastIndexOf(Object elem)

Searches backwards for the specified object, starting from the last position and returns an index to it.

Parameters:

elem - the desired element

Returns:

the index of the element, or -1 if it was not found.

public final synchronized int lastIndexOf(Object elem,
                                            int index)

Searches backwards for the specified object, starting from the specified position and returns an index to it.

Parameters:

elem - the desired element

index - the index where to start searching

Returns:

the index of the element, or -1 if it was not found.

public final synchronized Object elementAt(int index)

Returns the element at the specified index.

Parameters:

index - the index of the desired element

Throws: ArrayIndexOutOfBoundsException

If an invalid index was given.

public final synchronized Object firstElement()

Returns the first element of the sequence.

Throws: NoSuchElementException

If the sequence is empty.

public final synchronized Object lastElement()

Returns the last element of the sequence.

Throws: NoSuchElementException

If the sequence is empty.

public final synchronized void setElementAt(Object obj,
                                              int index)

Sets the element at the specified index to be the specified object. The previous element at that position is discarded.

Parameters:

obj - what the element is to be set to

index - the specified index

Throws: ArrayIndexOutOfBoundsException

If the index was invalid.

public final synchronized void removeElementAt(int index)

Deletes the element at the specified index. Elements with an index greater than the current index are moved down.

Parameters:

index - the element to remove

Throws: ArrayIndexOutOfBoundsException

If the index was invalid.

public final synchronized void insertElementAt(Object obj,
                                                 int index)

Inserts the specified object as an element at the specified index. Elements with an index greater or equal to the current index are shifted up.

Parameters:

obj - the element to insert

index - where to insert the new element

Throws: ArrayIndexOutOfBoundsException

If the index was invalid.

public final synchronized void addElement(Object obj)

Adds the specified object as the last element of the vector.

Parameters:

obj - the element to be added

public final synchronized boolean removeElement(Object obj)

Removes the element from the vector. If the object occurs more than once, only the first is removed. If the object is not an element, returns false.

Parameters:

obj - the element to be removed

Returns:

true if the element was actually removed; false otherwise.

public final synchronized void removeAllElements()

Removes all elements of the vector. The vector becomes empty.

public synchronized Object clone()

Clones this vector. The elements are not cloned.

Overrides:

clone in class Object

public final synchronized String toString()

Converts the vector to a string. Useful for debugging.

Overrides:

toString in class Object

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