Program on Collections Framework in Java

                     In this post, we will see a sample program which uses Collections framework in Java.


                      To find What is Collections Framework, What is the necessity of Collections framework in Java and Structure of Collections framework, please check this link: https://www.comrevo.com/2018/07/What-is-Collections-Framework-in-Java.html

Program (CollectionsDemo.java)

import java.util.*; public class CollectionsDemo {    public static void main(String[] args) {       // ArrayList        List a1 = new ArrayList();       a1.add("Rehan");       a1.add("Rehan");       a1.add("Kaira");       System.out.println(" ArrayList Elements");       System.out.print("\t" + a1);       // LinkedList       List l1 = new LinkedList();       l1.add("Rehan");       l1.add("Rehan");       l1.add("Kaira");       System.out.println();       System.out.println(" LinkedList Elements");       System.out.print("\t" + l1);       // HashSet       Set s1 = new HashSet();        s1.add("Rehan");       s1.add("Kaira");       s1.add("Sara");       System.out.println();       System.out.println(" HashSet Elements");       System.out.print("\t" + s1);       System.out.println();       // LinkedHashSet       Set lhs1 = new LinkedHashSet();        lhs1.add("Rehan");       lhs1.add("Kaira");       lhs1.add("Sara");       System.out.println();       System.out.println(" LinkedHashSet Elements");       System.out.print("\t" + lhs1);       System.out.println();       // TreeSet       Set t1 = new TreeSet();        t1.add("Rehan");       t1.add("Kaira");       t1.add("Sara");       System.out.println();       System.out.println(" TreeSet Elements");       System.out.print("\t" + t1);       System.out.println();       // Queue       Queue q1=new PriorityQueue();         q1.add("Rehan");         q1.add("Kaira");         q1.add("Sara");         q1.add("Parag");         q1.add("Soniya");         System.out.println(" Queue Elements");       System.out.print("\t" + q1);       System.out.print("\n");       System.out.println("head:"+q1.element());       System.out.print("\n");        //Deque       Deque d1=new ArrayDeque();         d1.add("Rehan");         d1.add("Kaira");         d1.add("Sara");         d1.offerFirst("Parag");        d1.offerLast("Soniya");       System.out.println(" Deque Elements");       System.out.print("\t" + d1);       System.out.print("\n");       System.out.println("head:"+d1.element());        // HashMap       Map m1 = new HashMap();        m1.put("Rehan", "8");       m1.put("Kaira", "31");       m1.put("Sara", "12");       m1.put("Parag", "14");       System.out.println();       System.out.println(" HashMap Elements");       System.out.print("\t" + m1);       System.out.print("\n");       // LinkedHashMap       Map lhm1 = new LinkedHashMap();        lhm1.put("Rehan", "8");       lhm1.put("Kaira", "31");       lhm1.put("Sara", "12");       lhm1.put("Parag", "14");       System.out.println();       System.out.println(" LinkedHashMap Elements");       System.out.print("\t" + lhm1);       System.out.print("\n");       // TreeMap       Map tm1 = new TreeMap();        tm1.put("Rehan", "8");       tm1.put("Kaira", "31");       tm1.put("Sara", "12");       tm1.put("Parag", "14");       System.out.println();       System.out.println(" TreeMap Elements");       System.out.print("\t" + tm1);       System.out.print("\n");    } }

  

Output: 

parag@parag-Inspiron-N4010:~/Desktop/programs$ javac CollectionsDemo.java  parag@parag-Inspiron-N4010:~/Desktop/programs$ java CollectionsDemo  ArrayList Elements [Rehan, Rehan, Kaira]   LinkedList Elements [Rehan, Rehan, Kaira]   HashSet Elements [Rehan, Sara, Kaira]  LinkedHashSet Elements [Rehan, Kaira, Sara]  TreeSet Elements [Kaira, Rehan, Sara]   Queue Elements [Kaira, Parag, Sara, Rehan, Soniya] head:Kaira  Deque Elements [Parag, Rehan, Kaira, Sara, Soniya] head:Parag  HashMap Elements {Rehan=8, Parag=14, Sara=12, Kaira=31}  LinkedHashMap Elements {Rehan=8, Kaira=31, Sara=12, Parag=14}  TreeMap Elements {Kaira=31, Parag=14, Rehan=8, Sara=12}