What operations exist in streams and what types of operations are there?

In Java 8+ streams provide a set of operations for processing data collections.

Types of operations:

1. Intermediate: Return a new stream. Can be performed lazily. Allow chaining of operations. They include:

   • filter()
   • map()
   • flatMap()
   • distinct()
   • sorted()
   • peek()
   • limit()
   • skip()

2. Terminal: End the stream, perform processing, and return a result or produce a side effect. After a terminal operation, the stream cannot be reused. They include:

   • forEach()
   • forEachOrdered()
   • toArray()
   • reduce()
   • collect()
   • count()
   • sum()
   • average()
   • min()
   • max()
   • anyMatch()
   • allMatch()
   • noneMatch()
   • findFirst()
   • findAny()

Example of a chain of operations:

// Intermediate operations (filter, map)
// Terminal operation (collect)
List<String> filteredList = originalList.stream()
    .filter(s -> s.startsWith("A")) // Filtering elements starting with "A"
    .map(String::toUpperCase) // Transforming to uppercase
    .collect(Collectors.toList()); // Collecting results into a List