Set contains() method in Java with Examples

The Java.util.Set.contains() method is used to check whether a specific element is present in the Set or not. So basically it is used to check if a Set contains any particular element.

Syntax:

boolean contains(Object element)

Parameters: The parameter element is of the type of Set. This is the element that needs to be tested if it is present in the set or not.

Return Value: The method returns true if the element is present in the set else return False.

Below program illustrate the Java.util.Set.contains() method:

// Java code to illustrate Set.contains() method
import java.io.*;
import java.util.*;

public class HashSetDemo {
    public static void main(String args[])
    {
        // Creating an empty Set
        Set<String> set = new HashSet<String>();

        // Using add() method to add elements into the Set
        set.add("Welcome");
        set.add("To");
        set.add("Geeks");
        set.add("4");
        set.add("Geeks");

        // Displaying the Set
        System.out.println("Set: " + set);

        // Check for "Geeks" in the set
        System.out.println("Does the Set contains 'Geeks'? "
                           + set.contains("Geeks"));

        // Check for "4" in the set
        System.out.println("Does the Set contains '4'? "
                           + set.contains("4"));

        // Check if the Set contains "No"
        System.out.println("Does the Set contains 'No'? "
                           + set.contains("No"));
    }
}

Output:

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

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Set.html#contains(java.lang.Object)