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Vector - Java Example Program


Vector
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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