Its functionality is exactly similar to ArrayList but Vector class belongs to synchronized whereas ArrayList belongs to non-synchronized class.
Creating a Vector is nothing but creating an object of java.util.Vector class.
Vector (); -- 1 Vector (int size); -- 2
public int size ();-- 3 public void addItem (Object obj); [old] -- 4 public void addElement (Object obj); [new] -- 5 public void addItem (int pos, Object obj); -- 6 public void addElement (int pos, Object obj); -- 7 public Object getItem (int pos); -- 8 public Object remove (int pos); -- 9 public void remove (Object obj ); -- 10 public void removeAll ();-- 11 public Enumeration elements ();-- 12
The methods 4,5,6 and 7 are used for adding an object to the vector either at end or at specified position. Method-12 is used for extracting the data from vector object.
Enumeration en=v.elements (); While (en.hasMoreElements()) { Object obj=en.nextElement (); System.out.println(obj); }
Write a java program which listed the concept of Vector?
Answer:
import java.util.*; class vector { public static void main(String[] args) { Vector v = new Vector(); v.addElement(new Integer(10)); v.addElement(new Float(100.37f)); v.addElement(new Boolean(true)); v.addElement("K.V.R"); System.out.println("SIZE = " + v.size()); System.out.println("CONTENTS = " + v); Enumeration en = v.elements(); while (en.hasMoreElements()) { Object val = en.nextElement(); System.out.println(val); } } };
public boolean hasMoreElements (); -- 1 public Object nextElement(); -- 2
Method-1 is used for checking weather we have next elements or not. This method returns false when we have next element otherwise it returns false. Method-2 is used for obtaining next element. Method-2 can be used as long as method-1 returns true .
Stack (); Stack (int size);
public boolean empty ();-- 1 public void push (Object); -- 2 public Object pop (); -- 3 public Object peek (); -- 4 public int search (Object); -- 5
Method-1 returns true when the Stack does not contain any elements otherwise false. Method-2 is used for inserting an object into the Stack. Method-3 is used to remove top most elements permanently. Method-4 is used to retrieve top most elements without removing. Method- 5 returns relative position of the element, if it found otherwise returns -1.
Write a java program which illustrates the concept of Stack?
Answer:
import java.util.*; class stack { public static void main(String[] args) { Stack st = new Stack(); System.out.println("IS STACK EMPTY ? " + st.empty()); System.out.println(st); st.push(new Integer(10)); st.push(new Integer(20)); st.push(new Integer(30)); st.push(new Integer(40)); System.out.println(st); System.out.println("TOP MOST ELEMENT = " + st.peek()); System.out.println(st); System.out.println("DELETED ELEMENT = " + st.pop()); System.out.println("MODIFIED STACK = " + st.peek()); System.out.println("IS 10 FOUND ? " + st.search(new Integer(10))); Enumeration en = st.elements(); while (en.hasMoreElements()) { Object obj = en.nextElement(); System.out.println(obj); } } };