♠ Posted by Unknown in Core Java at 01:26
Vector class
The Vector class contained in the java.util
package. This class can be used to create a generic dynamic array known as
vector that can hold objects of any type and any number. The objects do not
have to be homogenous. Arrays can be easily implemented as vectors. Vectors are
created like arrays as follows:
Vector intVect = new
Vector(); //declaring without size
Vector list = new
Vector(3); //declaring with size
The
vector can be declared without specifying any size explicitly. A vector can
accommodate an unknown number of items. Even, when a size is specified, this
can be overlooked and a different number of items may be put into the vector.
Remember, in contrast, an array must always have its size specified.
Vectors
possess a number of advantages over arrays.
1. It is convenient to use vectors to store objects.
2. A vector can be used to store a list of objects that
may vary in size.
3. We can add and delete objects from the list as and when
required.
A
major constraint in using vectors is that we cannot directly stores simple data
types in a vector; we can only store objects.
list.addElement(item) |
Adds
the item specified to the list at the end
|
list.elementAt(10) |
Gives
the name of the 10th object
|
list.size() |
Gives
the number of objects present
|
list.removeElement(item) |
Removes
the specified item from the list
|
list.removeAllElements() |
Removes
the item stored in the nth position of the list
|
list.copyInto(array) |
Copies
all items from list to array
|
list.insertElementAt(item, n) |
Inserts
the item at nth position
|
import
java.util.*;
class LanguageVector
{
public static void
main(String[] args)
{
Vector list
= new Vector();
int length =
args.length;
for(int i =
0; i < length; i++)
{
list.addElement(args[i]);
}
list.insertElementAt("COBOL",
2);
int size =
list.size();
String
listArray[] = new String[size];
list.copyInto(listArray);
System.out.println("List
of Languages");
for(int i =
0; i < size; i++)
{
System.out.println(listArray[i]);
}
}
}
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