Understanding when to use stream() vs forEach() in Java
03 Nov 2024
In Java, choosing between Stream() and ForEach() depends on what you want to do with your data. While both are used to iterate over collections, each has its own strengths.
stream()
Using stream() is powerful for complex data transformations, allowing operations like filtering, mapping, and reducing. It’s ideal for:
- Transformations and filters: Use Stream() to apply operations like filtering, mapping, grouping, or reducing data.
- Chained processing: Apply multiple operations in a single chain.
- Parallel processing: For large datasets, use parallelStream() to leverage multi-core processors.
- Immutability: Streams avoid side effects, allowing new collections to be generated without changing the original.
Example:
List<String> names = Arrays.asList("Maria", "José", "João");
List<String> filteredNames = names.stream()
.filter(name -> name.startsWith("J"))
.map(String::toUpperCase)
.collect(Collectors.toList());
The results will be a new list only with the names started with J in uppercase.
