Java: Get the number of elements in a hash set

Last update on May 22 2025 13:15:51 (UTC/GMT +8 hours)

3. Get HashSet Size

Write a Java program to get the number of elements in a hash set.

Sample Solution:

Java Code:

import java.util.*;
import java.util.Iterator;
  public class Exercise3 {
  public static void main(String[] args) {
         // Create a empty hash set
     HashSet<String> h_set = new HashSet<String>();
   // use add() method to add values in the hash set
          h_set.add("Red");
          h_set.add("Green");
          h_set.add("Black");
          h_set.add("White");
          h_set.add("Pink");
          h_set.add("Yellow");
    System.out.println("Original Hash Set: " + h_set);
    System.out.println("Size of the Hash Set: " + h_set.size());
   }
}

Sample Output:

Original Hash Set: [Red, White, Pink, Yellow, Black, Green]            
Size of the Hash Set: 6 

Pictorial Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to determine the size of a HashSet after performing bulk insertion and deletion operations.
• Write a Java program to count the elements in a HashSet using Java streams and compare the result with the size() method.
• Write a Java program to update a HashSet concurrently and then obtain its final size using synchronized blocks.
• Write a Java program to implement a custom method to count the number of elements in a HashSet without calling the size() method.

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