How do terminal and non-terminal operations in Stream API differ in their functions and purpose?

In the Stream API, terminal and non-terminal operations differ in their purpose and behavior:

• Non-terminal operations (intermediate) are operations that return a new stream and allow building a chain of transformations. They are lazy, meaning they are not executed immediately but only when a terminal operation is invoked. Examples: filter(), map(), sorted(), distinct().

• Terminal operations (terminal) complete the chain of operations and trigger data processing. They return a result (for example, a collection, a number, or void). After a terminal operation, the stream is considered closed and cannot be reused. Examples: collect(), forEach(), reduce(), count().

Example:

List<String> result = list.stream()
    .filter(s -> s.startsWith("A"))   // non-terminal
    .map(String::toUpperCase)           // non-terminal
    .collect(Collectors.toList());     // terminal

Here, filtering and transformation are not executed immediately but only when collect() is called, which triggers processing and returns the final list.