TreeSet forEach(Consumer) in Java

forEach(Consumer): This method is available in java.util.TreeSet 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.TreeSet;

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

        TreeSet<String> treeSet = new TreeSet<String>();

        treeSet.add("Hello");
        treeSet.add("Java");
        treeSet.add("Program");
        treeSet.add("C++");

        treeSet.forEach((n -> System.out.print(n + " ")));

    }
}

Output:

C++ Hello Java Program 

Approach 2: NullPointerException

Java

import java.util.TreeSet;

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

        TreeSet<String> treeSet = new TreeSet<String>();

        treeSet.add("Hello");
        treeSet.add("Java");
        treeSet.add("Program");
        treeSet.add("C++");

        treeSet.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)