Java: Remove all of the elements from a hash set

Last update on March 12 2025 13:32:47 (UTC/GMT +8 hours)

Write a Java program to remove all elements from a hash set.

Sample Solution:

Java Code:

import java.util.*;
  public class Exercise12 {
  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");
           System.out.println("Original hash set contains: "+ h_set);
      //  clear() method removes all the elements from a hash set
      // and the set becomes empty.
          h_set.clear();
 
     // Display original hash set content again
          System.out.println("HashSet content: "+h_set);
     }
}

Sample Output:

Original hash set contains: [Red, White, Black, Green]                 
HashSet content: []

Pictorial Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to clear a HashSet using the clear() method and then verify it is empty using isEmpty().
• Write a Java program to remove all elements from a HashSet by iterating over it and calling remove() on each element.
• Write a Java program to filter a HashSet with Java streams to an empty set and then check its size.
• Write a Java program to simulate emptying a HashSet by reassigning it to a new instance and comparing the two.

Java Code Editor:

Contribute your code and comments through Disqus.

Previous: Compare two sets and retain elements which are same on both sets.
Next: Create a new tree set, add some colors and print out the tree set.