What is the purpose of the forEach() method in the Stream API?

a) To count the elements in the stream

b) To iterate over each element in the stream and perform an action

c) To remove duplicates from the stream

d) To sort the elements in the stream

Answer:

b) To iterate over each element in the stream and perform an action

Explanation:

The forEach() method in the Stream API is a terminal operation that iterates over each element in the stream and performs the specified action. This method is often used to perform side effects, such as printing elements to the console, logging information, or updating external data structures. The action passed to the forEach() method must be a functional interface that takes an element as input and performs some operation on it.

For example, you might use forEach() to print each element of a list to the console or to add each element to a new collection. Since forEach() is a terminal operation, invoking it consumes the stream, meaning that the stream cannot be reused afterward. This method is particularly useful when you want to perform an action on each element of a stream without needing to return a new collection or value.

However, it’s important to note that using forEach() in parallel streams can lead to non-deterministic behavior if the action involves modifying shared state. In such cases, developers should ensure that the action performed is thread-safe or consider using other stream operations that do not involve side effects. The forEach() method is a powerful tool for performing actions on elements in a stream, but it should be used with care in concurrent environments.