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      Course
      Set Interface

      Java Tutorial

      This Java tutorial is tailored for newcomers, offering a journey from basic principles to complex Java programming techniques. Completing this tutorial equips you with a solid understanding of Java, preparing you for advanced learning. You'll emerge ready to tackle the challenges of becoming a top-tier software engineer, with the skills to innovate and excel in the vast world of software development.

      Set Interface

      A Set is a Collection that cannot contain duplicate elements. It models the mathematical set abstraction.
      The Set interface contains only methods inherited from Collection and adds the restriction that duplicate elements are prohibited.
      Set also adds a stronger contract on the behavior of the equals and hashCode operations, allowing Set instances to be compared meaningfully even if their implementation types differ.

      Set Interface Methods

      The methods declared by Set are summarized in the following table
      Sr.No.
      Method & Description
      1
      add( )
      Adds an object to the collection.
      2
      clear( )
      Removes all objects from the collection.
      3
      contains( )
      Returns true if a specified object is an element within the collection.
      4
      isEmpty( )
      Returns true if the collection has no elements.
      5
      iterator( )
      Returns an Iterator object for the collection, which may be used to retrieve an object.
      6
      remove( )
      Removes a specified object from the collection.
      7
      size( )
      Returns the number of elements in the collection.

      Set Interface Examples

      Set has its implementation in various classes like HashSet, TreeSet, LinkedHashSet. Below are some of the implementations of the Set interface in Java.

      Example to Implement Set Using HashSet

      Following is an example to explain Set functionality using HashSet 
      import java.util.HashSet;
      import java.util.Set;
      
      public class SetDemo {
      
        public static void main(String args[]) { 
            int count[] = {34, 22,10,60,30,22};
            Set<Integer> set = new HashSet<>();
            try {
               for(int i = 0; i < 5; i++) {
                  set.add(count[i]);
               }
               System.out.println(set);
            }
            catch(Exception e) {}
         }
      }

      Output

      [34, 22, 10, 60, 30]

      Example to Implement Set Using TreeSet

      Following is an example to explain Set functionality using TreeSet 
      import java.util.HashSet;
      import java.util.Set;
      import java.util.TreeSet;
      
      public class SetDemo {
      
        public static void main(String args[]) { 
            int count[] = {34, 22,10,60,30,22};
            Set<Integer> set = new HashSet<>();
            try {
               for(int i = 0; i < 5; i++) {
                  set.add(count[i]);
               }
               System.out.println(set);
      
               TreeSet<Integer> sortedSet = new TreeSet<>(set);
               System.out.println("The sorted list is:");
               System.out.println(sortedSet);
      
               System.out.println("The First element of the set is: "+ (Integer)sortedSet.first());
               System.out.println("The last element of the set is: "+ (Integer)sortedSet.last());
            }
            catch(Exception e) {}
         }
      }

      Output

      [34, 22, 10, 60, 30]
      The sorted list is:
      [10, 22, 30, 34, 60]
      The First element of the set is: 10
      The last element of the set is: 60

      Example to Implement Set Using LinkedHashSet

      Following is an example to explain Set functionality using LinkedHashSet opearations 
      import java.util.LinkedHashSet;
      import java.util.Set;
      
      public class SetDemo {
      
        public static void main(String args[]) { 
            int count[] = {34, 22,10,60,30,22};
            Set<Integer> set = new LinkedHashSet<>();
            try {
               for(int i = 0; i < 5; i++) {
                  set.add(count[i]);
               }
               System.out.println(set);
            }
            catch(Exception e) {}
         }
      }

      Output

      [34, 22, 10, 60, 30]