Vector - Java Example Program

Vector

CODE

import java.util.Enumeration;
import java.util.Vector;

class VectorTest
{
    public static void main(String arg[])
    {
        // initial size is set to 3, increment is 2
        Vector v = new Vector(3, 2);
        System.out.println(" size: " + v.size()); // sixe method
        System.out.println("Initial capacity: " + v.capacity()); // capacity method
        
        v.add(1); // add method
        v.addElement(new Integer(2));
        v.addElement(new Integer(3));
        v.addElement(new Integer(4));
        System.out.println("Capacity after four additions: " + v.capacity());
        
        v.addElement(new Double(5.45));
        System.out.println("Current capacity: " + v.capacity());
        v.addElement(new Double(6.08));
        v.addElement(new Integer(7));
        System.out.println("Current capacity: " + v.capacity());
        v.addElement(new Float(9.4));
        v.addElement(new Integer(10));
        System.out.println("Current capacity: " + v.capacity());
        v.addElement(new Integer(11));
        v.addElement(new Integer(12));
        
        System.out.println("First element: " + v.firstElement()); // first element method
        System.out.println("Last element: " + v.lastElement()); // last element method
        
        if (v.contains(new Integer(3))) // contains method
            System.out.println("Vector contains 3.");
        
        // enumerate the elements in the vector.
        Enumeration e = v.elements(); // Enumeration
        System.out.print("Elements in vector : ");
        while (e.hasMoreElements())
            System.out.print(e.nextElement() + " ");    
    }
}

OUTPUT

size: 0
Initial capacity: 3
Capacity after four additions: 5
Current capacity: 5
Current capacity: 7
Current capacity: 9
First element: 1
Last element: 12
Vector contains 3.
Elements in vector : 1 2 3 4 5.45 6.08 7 9.4 10 11 12

DESCRIPTION

In this program, a Vector constructor is taken where the initial size is set to 3 and the increment of size 2 for every additional element. The size of vector is 0 because no element in inserted and capacity is 3 i.e. initial size set is 3. Four Integers are added, now the capacity becomes 5 i.e. initial 3 + increment 2, a double is added to vector the capacity remains same and again two elements are added then the capacity becomes 7 i.e. 5+2, and again two elements are added so capacity becomes 9 and again two elements are added to the vector. The first and last elements are retrieved and the existence of 3 elements checked and then vector is assigned to Enumeration and printed the vector elements.

THINGS TO TRY

Add element 8 in to the vector at index 8 by using add(int index, Object element).

Use the clone, clear, elementAt or get and hashCode methods to clone, clear, to get element at specified index and to get the hash code of the vector.

Apply equals, indexOf, isEmpty, lastIndexOf, remove, retain and set methods to vector.

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