Set contains() method in Java with Examples

Last Updated : 26 Dec, 2025

Set.contains() method in Java is used to check if a specific element exists in a Set. It returns true if the element is present, otherwise false. This method is useful for quickly verifying membership in collections that do not allow duplicates, like HashSet or TreeSet.

Example:

Java 
import java.util.*;
public class GFG {
    public static void main(String[] args) {
        Set<String> fruits = new HashSet<>();
        fruits.add("Apple");
        
        System.out.println("Does the set contain Apple?: " + fruits.contains("Apple"));
        System.out.println("Does the set contain Orange?: " + fruits.contains("Orange"));
    }
}

Output
Does the set contain Apple?: true
Does the set contain Orange?: false

Explanation:

  • Set<String> fruits = new HashSet<>(): creates a HashSet.
  • contains() checks whether "Apple" and "Orange" exist in the set.
  • "Apple" exists, so it returns true; "Orange" does not, so it returns false.

Syntax

boolean contains(Object element)

  • Parameters: "element" to check for in the set.
  • Return Value: returns true if the set contains the specified element, false otherwise

Example:This code shows how Set.contains() checks for an element in a HashSet.

Java 
import java.util.*;
public class HashSetDemo {
    public static void main(String[] args) {
        Set<String> set = new HashSet<>();
        set.add("Welcome");
        set.add("To");
        set.add("Geeks");
        set.add("4");
        set.add("Geeks");
        
        System.out.println("Set: " + set);
        System.out.println("Does the Set contain 'Geeks'?: " + set.contains("Geeks"));
        System.out.println("Does the Set contain '4'?: " + set.contains("4"));
        System.out.println("Does the Set contain 'No'?: " + set.contains("No"));
    }
}

Output
Set: [4, Geeks, Welcome, To]
Does the Set contain 'Geeks'?: true
Does the Set contain '4'?: true
Does the Set contain 'No'?: false

Explanation:

  • Duplicate entries are ignored automatically in a Set.
  • contains() checks for the presence of an element in the set.
  • The method returns true for existing elements and false for elements not in the set.

Note:Works for all Set types (HashSet, TreeSet, LinkedHashSet), has O(1) time complexity for HashSet.contains().

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