Last Updated on August 1st, 2024

Which of these does Stream.forEach() operates on?

A) Function
B) Consumer
C) Producer
D) Predicate

Ans. B) Consumer 

Explanation

The stream.forEach() method in Java’s Stream API operates on a Consumer. Here’s a detailed explanation:

Stream API: Java introduced the Stream API in Java 8, which provides a functional approach to processing sequences of elements. Streams can be created from various data sources, including collections, arrays, and I/O channels.

forEach() Method: The forEach() method is a terminal operation in the Stream API that performs an action for each element of the stream. This method takes a Consumer as an argument.

Consumer: A Consumer is a functional interface defined in the java.util.function package. It represents an operation that accepts a single input argument and returns no result. The functional method of Consumer is accept(T t). When we use stream.forEach(), we provide a Consumer implementation, typically as a lambda expression or method reference, which specifies the action to be performed on each element.

Example:

Here’s a simple example demonstrating how forEach() operates on a Consumer:

import java.util.Arrays;
import java.util.List;

public class StreamForEachExample {
    public static void main(String[] args) {
        List<String> names = Arrays.asList("Core Java", "Spring", "Hibernate");

        // Using forEach with a lambda expression
        names.stream().forEach(name -> System.out.println(name));

        // Using forEach with a method reference
        names.stream().forEach(System.out::println);
    }
}

In this example:

names.stream() creates a stream from the list names.

forEach(name -> System.out.println(name)) uses a lambda expression, which is a Consumer that prints each name.

forEach(System.out::println) uses a method reference, which is also a Consumer.

Thus, B) Consumer the correct answer.

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