Vector Class

  1. The underlying data structure for the vector is resizable array or grow able array.
  2. Duplicates objects are allowed.
  3. Insertion order is preserved.
  4. Null insertion is possible.
  5. Heterogeneous objects are allowed.
  6. Vector class implemented Serializable, Cloneable and RandomAccess.
  7. Most of the methods present in vector are synchronized. Hence vector object is thread safe.
  8. Best choice if frequent operation is retrieved.

Methods of vector class

For adding objects:-

add(Object o) [from Collection-List l]
add() [from List]
addElement(Object o) [from Vector]

For removing objects:-

remove(Object o) [from Collection]
removeElement(Object o) [from Vector]
remove(int index) [from List]
removeElementAt(int index) [from Vector]
clear() [from Collection]
removeAllElements() [from Vector]
=

For accessing elements:-

Object get(int index) [from Collection]
Object elementAt(int index) [from Vector]
Object firstElement() [from Vector]
Object lastElement() [from Vector]

Other Methods:-

int Size();
int Capacity();
Enumeration elements ();

Constructors of Vector class

Vector v = new Vector();

Creates an empty vector object with default initial capacity 10, once vector reaches its maximum capacity a new object will be created with new capacity.

             New Capacity = 2*Current Capacity

Vector v = new Vector(int initial capacity);

Creates an empty vector object with specified initial capacity.

Vector v = new Vector(int initial capacity, int incremental capacity)
Vector v = new Vector(Collection c);

Creates an equivalent vector object for the given collection.

Example

package List;

import java.util.Vector;

public class VectorDemo {
	public static void main(String[] args) {
		Vector v = new Vector();
		System.out.println(v.capacity()); // 10
		for (int i = 1; i <= 10; i++) {
			v.addElement(i);
		}
		System.out.println(v.capacity()); // 10
		v.addElement("A");
		System.out.println(v.capacity()); // 20
		System.out.println(v); // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, A]

	}

}

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