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§3.10 Class Vector
public class java.util.Vector
extends java.lang.Object (I-§1.12)
implements java.lang.Cloneable (I-§1.22)
{
// Fields
protected int capacityIncrement; §3.10.1
protected int elementCount; §3.10.2
protected Object elementData[]; §3.10.3
// Constructors
public Vector(); §3.10.4
public Vector(int initialCapacity); §3.10.5
public Vector(int initialCapacity, §3.10.6
int capacityIncrement);
// Methods
public final void addElement(Object obj); §3.10.7
public final int capacity(); §3.10.8
public Object clone(); §3.10.9
public final boolean contains(Object elem); §3.10.10
public final void copyInto(Object anArray[]); §3.10.11
public final Object elementAt(int index); §3.10.12
public final Enumeration elements(); §3.10.13
public final void ensureCapacity(int minCapacity) §3.10.14
public final Object firstElement(); §3.10.15
public final int indexOf(Object elem); §3.10.16
public final int indexOf(Object elem, int index); §3.10.17
public final void insertElementAt(Object obj, int index); §3.10.18
public final boolean isEmpty(); §3.10.19
public final Object lastElement(); §3.10.20
public final int lastIndexOf(Object elem); §3.10.21
public final int lastIndexOf(Object elem, int index); §3.10.22
public final void removeAllElements(); §3.10.23
public final boolean removeElement(Object obj); §3.10.24
public final void removeElementAt(int index); §3.10.25
public final void setElementAt(Object obj, int index); §3.10.26
public final void setSize(int newSize); §3.10.27
public final int size(); §3.10.28
public final String toString(); §3.10.29
public final void trimToSize(); §3.10.30
}
The 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 Vector can grow or
shrink as needed to accommodate adding and removing items after the Vector has been created.
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 components are added to the vector, the vector's storage increases in chunks the
size of capacityIncrement. An application can increase the capacity of a vector before inserting a large number of components; this reduces the amount of incremental reallocation.
capacityIncrement
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 is 0,
the capacity of the vector is doubled each time it needs to grow.
elementCount
protected int elementCount
- The number of valid components in the vector.
elementData
protected Object elementData[]
- The array buffer into which the components of the vector are stored. The
length of this array buffer is the (current) capacity of the vector.
Vector
public Vector()
- Constructs an empty vector.
Vector
public Vector(int initialCapacity)
- Constructs an empty vector. It initial capacity is the specified argument
size.
- Parameters:
initialCapacity
-
the initial capacity of the vector
Vector
public Vector(int initialCapacity, int capacityIncrement)
- Constructs an empty vector with the specified capacity and the specified
capacity increment.
- Parameters:
initialCapacity
-
the initial capacity of the vector
capacityIncrement
-
the amount by which the capacity is increased when
the vector overflows.
addElement
public final void addElement(Object 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.
- Parameters:
obj
-
the component to be added
capacity
public final int capacity()
- Returns:
- the current capacity of this vector.
clone
public Object clone()
- Returns:
- a clone of this vector.
- Overrides:
- clone() in class Object (I-§1.12.2).
contains
public final boolean contains(Object elem)
- Parameters:
elem
-
an object
- Returns:
- true if the specified object is an component in this vector; false otherwise.
copyInto
public final void copyInto(Object anArray[])
- Copies the components of this vector into the specified array. The array
must be big enough to hold all the objects in this vector.
- Parameters:
anArray
-
the array into which the components get copied.
elementAt
public final Object elementAt(int index)
- Parameters:
index
-
an index into this vector
- Returns:
- the component at the specified index.
- Throws
- ArrayIndexOutOfBoundsException (I-§1.25)
- If an invalid index was given.
elements
public final Enumeration elements()
- Returns:
- an enumeration (I-§3.11) of the components of this vector.
ensureCapacity
public final 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.
- Parameters:
minCapacity
-
the desired minimum capacity
firstElement
public final Object firstElement()
- Returns:
- the first component of this vector.
- Throws
- NoSuchElementException (I-§3.14)
- If this vector has no components.
indexOf
public final int indexOf(Object elem)
- Parameters:
elem
-
an object
- Returns:
- the index of the first occurrence of the argument in this vector; returns
-1 if the object is not found.
indexOf
public final int indexOf(Object elem, int index)
- Parameters:
elem
-
an object
index
-
the index where to start searching
- Returns:
- the index of the first occurrence of the object argument in thisn vector
at position index or later in the vector; returns -1 if the object is not
found.
insertElementAt
public final void insertElementAt(Object obj, int index)
- Inserts the specified object as an 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 (I-§3.10.28) of the vector.
- Parameters:
obj
-
the component to insert
index
-
where to insert the new component
- Throws
- ArrayIndexOutOfBoundsException (I-§1.25)
- If the index was invalid.
isEmpty
public final boolean isEmpty()
- Returns:
- true if this vector has no components; false otherwise.
lastElement
public final Object lastElement()
- Returns:
- the last component of the vector, i.e. the component at index
.
- Throws
- NoSuchElementException (I-§3.14)
- If this vector is empty.
lastIndexOf
public final int lastIndexOf(Object elem)
- Parameters:
elem
-
the desired component
- Returns:
- the index of the last occurrence of the argument in this vector; returns
-1 if the object is not found.
lastIndexOf
public final int lastIndexOf(Object elem, int index)
- Searches backwards for the specified object, starting from the specified
index and returns an index to it.
- Parameters:
elem
-
the desired component
index
-
the index where to start searching
- Returns:
- the index of the last occurrence of the object argument in this vector at
position less than index in the vector; returns -1 if the object is not
found.
removeAllElements
public final void removeAllElements()
- Removes all components from this vector and sets its size to zero.
removeElement
public final boolean removeElement(Object obj)
- Removes the first 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
- Parameters:
obj
-
the component to be removed
- Returns:
- true if the argument was a component of this vector; false otherwise.
removeElementAt
public final 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 index must be a value greater than or equal to 0 and less than the current size (I-§3.10.28) of the vector.
- Parameters:
index
-
the index of the object to remove
- Throws
- ArrayIndexOutOfBoundsException (I-§1.25)
- If the index was invalid.
setElementAt
public final void setElementAt(Object 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 (I-§3.10.28) of the vector.
- Parameters:
obj
-
what the component is to be set to
index
-
the specified index
- Throws
- ArrayIndexOutOfBoundsException (I-§1.25)
- If the index was invalid.
setSize
public final 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
- Parameters:
newSize
-
the new size of this vector
size
public final int size()
- Returns:
- the number of components in this vector.
toString
public final String toString()
- Creates a string representation of this vector.
- Returns:
- a string representation of this vector.
- Overrides:
- toString in class Object (I-§1.12.9).
trimToSize
public final void trimToSize()
- Trims the capacity of this vector to be the vector's current size
(I-§3.10.28). An application can use this operation to minimize the storage
of a vector.
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Java API Document (HTML generated by dkramer on April 22, 1996)
Copyright © 1996 Sun Microsystems, Inc.
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Please send any comments or corrections to doug.kramer@sun.com