17-03-25
-----------
Q)Explain about Collections class.
=>java.util.Collections  is a library class of Java collection framework.
=>It is a utility class (helper class).
=>It has static methods that act upon collections.
=>Some important methods of this class are
      addAll(collection,e1,e2,e3.....);
      min(collection)
      max(collection)
      reverse(collection)
      sort(collection)
      sort(collection,Collections.reverseOrder())
      binarySearch(collection,element)
Q)Example program on the methods of Collections class.
import java.util.*;
class CollectionsExample{    
	public static void main(String[] args){
		ArrayList<Integer> alist=new ArrayList<>();//list based collection object created.
		Collections.addAll(alist,10,13,8,45,4,40,27,12);
		System.out.println(alist);
		System.out.println("45 is found at the index "+Collections.binarySearch(alist,45));
		Collections.sort(alist);//sorts in ascending order
		System.out.println(alist);
		Collections.sort(alist,Collections.reverseOrder());//sorts in descending order
		System.out.println(alist);
		System.out.println("Smallent element in the collection is "+Collections.min(alist));
		System.out.println("Largest element in the collection is "+Collections.max(alist));
	}
}

Q)Explain about  Collection interface.
=>java.util.Collection interface is the foundation for Java collection framework.

=>There is no direct implementation class for this method.

=>For list based and set based   collections(group of objects) whatever functionality is commonly required, it is specified in this interface.

HIERARCHY DIAGRAM

=>java.util.Collection interface has the following important methods.

add()
addAll()
contains()
clear()
isEmpty()
remove()
removeAll()
size()