What are intermediate and terminal operators in Stream? Provide examples.

In Java Stream API, operators are divided into intermediate and terminal.

Intermediate operators return a new Stream and allow chaining operations. They are lazy, meaning they do not execute until a terminal operator is called.

Examples of intermediate operators:

• filter(Predicate) — filtering elements
• map(Function) — transforming elements
• sorted() — sorting
• distinct() — removing duplicates

Terminal operators end the chain and return a result (not a Stream). They trigger the execution of all intermediate operations.

Examples of terminal operators:

• collect(Collector) — collecting elements into a collection
• forEach(Consumer) — performing an action for each element
• reduce(BinaryOperator) — folding elements
• count() — counting elements

Example:

List<String> names = List.of("Anna", "Bob", "Alice", "Brian");
long count = names.stream()
    .filter(name -> name.startsWith("A")) // intermediate operator
    .count(); // terminal operator
System.out.println(count); // Will output 2