Can you list the main categories of methods used in the Stream API?

In Java Stream API, the main categories of methods can be divided into three groups:

1. Intermediate operations:

   • Return a new Stream, allowing chaining of operations.
   • Examples: filter(), map(), flatMap(), distinct(), sorted(), limit(), skip().

2. Terminal operations:

   • End the chain and return a result (not a Stream).
   • Examples: forEach(), collect(), reduce(), count(), anyMatch(), allMatch(), noneMatch(), findFirst(), findAny().

3. Stream creation operations:

   • Methods for creating streams from collections, arrays, values.
   • Examples: Stream.of(), Collection.stream(), Arrays.stream().

Example usage:

List<String> names = Arrays.asList("Anna", "Bob", "Charlie", "David");

long count = names.stream() // creating a Stream
    .filter(name -> name.length() > 3) // intermediate operation
    .count(); // terminal operation

System.out.println(count); // Outputs the number of names longer than 3

Thus, the main categories of Stream API methods are creation operations, intermediate operations, and terminal operations.