How to distinguish operators that perform intermediate actions from those that terminate the data stream?

In stream data (Streams), operators are divided into intermediate and terminal:

• Intermediate operators return a new stream and allow chaining operations. They are lazy — they do not execute until a terminal operator is called. Examples: map(), filter(), sorted().

• Terminal operators complete the stream, perform computations, and return a result or side effect. After their invocation, the stream is considered closed. Examples: collect(), forEach(), reduce(), count().

To distinguish:

• If the operator returns a Stream — it is intermediate.
• If it returns something other than Stream (e.g., a collection, a number, void) — it is terminal.

Example:

Stream.of(1, 2, 3)
    .filter(n -> n > 1) // intermediate
    .map(n -> n * 2)     // intermediate
    .forEach(System.out::println); // terminal