HashSet forEach(Consumer) in Java

forEach(Consumer): This method is available in java.util.HashSet class of Java.

Syntax:

void java.lang.Iterable.forEach(Consumer<? super K> action)

This method takes one argument. This method performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception.

Parameters: One parameter is required for this method.

action: The action to be performed for each element.

Throws:

NullPointerException - if the specified action is null.

Approach 1: When no exception

Java

import java.util.HashSet;

public class HashSetforEach {
    public static void main(String[] args) {

        HashSet<String> hashSet = new HashSet<String>();

        hashSet.add("Hello");
        hashSet.add("Java");
        hashSet.add("C++");
        hashSet.add("Hello");

        hashSet.forEach(k -> System.out.print(k + " "));

    }
}

Output:

Java C++ Hello 

Approach 2: NullPointerException 

Java

import java.util.HashSet;

public class HashSetforEach {
    public static void main(String[] args) {

        HashSet<String> hashSet = new HashSet<String>();

        hashSet.add("Hello");
        hashSet.add("Java");
        hashSet.add("C++");
        hashSet.add("Hello");

        hashSet.forEach(null);

    }
}

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:208)
	at java.base/java.lang.Iterable.forEach(Iterable.java:73)