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Set removeAll() Method in Java

Last Updated : 11 Jul, 2025
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In Java, the removeAll() method is part of the Collection interface. It is used to remove all elements from a collection that are present in another collection.

Example 1: This example demonstrates how the removeAll() method removes all elements from the first set that are also present in the second set.

Java 
// Java Program to demosntrates
// the working of Set removeAll()
import java.util.HashSet;
import java.util.Set;

public class Geeks {
    public static void main(String[] args)
    {
        // Adding elements in the first set
        Set<String> s1 = new HashSet<>();
        s1.add("Geek1");
        s1.add("Geek2");
        s1.add("Geek3");
        s1.add("Geek4");

        // Adding elements in the second set
        Set<String> s2 = new HashSet<>();
        s2.add("Geek3");
        s2.add("Geek4");

        System.out.println("Set1 before removeAll(): " 
        + s1);

        // Remove all elements of s2 from s1
        s1.removeAll(s2);

        System.out.println("Set1 after removeAll(): " 
        + s1);
    }
}

Output
Set1 before removeAll(): [Geek4, Geek3, Geek2, Geek1]
Set1 after removeAll(): [Geek2, Geek1]

Syntax of removeAll() Method

boolean removeAll(Collection<?> c)

  • Parameter: The collection "c" contains the elements to be removed from the calling collection. If an element in c matches any element in the original collection, it will be removed.
  • Return Type: This method return "true" if elements are removed, otherwise it return "false".

Example 2: This example shows how removeAll() returns a boolean indicating whether any elements were removed from the first set by comparing it to the second set.

Java 
// Java program to demosntrates that 
// removeAll() returns boolean value
import java.util.HashSet;
import java.util.Set;

public class Geeks {
    public static void main(String[] args) {
        
        Set<String> s1 = new HashSet<>();
        s1.add("Geek1");
        s1.add("Geek2");
        s1.add("Geek3");

        Set<String> s2 = new HashSet<>();
        s2.add("Geek2");
        s2.add("Geek3");

        // Removing elements that 
        // exist in s2 from s1
        boolean res1 = s1.removeAll(s2);
        System.out.println("Set1 after removing Set2 elements from it: " 
        + s1);
        System.out.println("Was the collection modified? " 
        + res1);
    }
}

Output
Set1 after removing Set2 elements from it: [Geek1]
Was the collection modified? true

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