Advanced Stream Operations

flatMap, reduce, groupingBy

6 min read

Advanced Stream Operations

Advanced operations enable complex data transformations.

Code Examples

reduce and groupingBy

java
1
2int sum = list.stream()
3    .reduce(0, Integer::sum);
4
5Map<String, List<User>> grouped =
6    users.stream().collect(Collectors.groupingBy(User::getRole));
7

Use Cases

  • Complex aggregations
  • Analytics pipelines

Common Mistakes to Avoid

  • Overusing streams
  • Hard-to-read pipelines