Using streams in Java allows for efficient and concise processing of collections and other data sources. Streams provide a declarative approach to perform operations on sequences of elements, leveraging functional programming concepts.
| Operation | Traditional Approach | Stream API Approach | Description |
|---|---|---|---|
| Filtering | Loop with if condition |
collection.stream().filter(e -> e.startsWith("A")) |
Filters elements that match a condition. |
| Mapping | Loop with manual transformation | stream.map(String::toUpperCase) |
Transforms each element (e.g., to uppercase). |
| Sorting | Use Collections.sort() |
stream.sorted() |
Sorts the elements in natural order or with a custom comparator. |
| Finding | Loop with if and break |
stream.findFirst() or stream.findAny() |
Retrieves the first or any matching element. |
| Matching | Loop with conditions and boolean flags | stream.anyMatch(), allMatch(), noneMatch() |
Checks if elements match a condition. |
| Collecting | Use manual list or set and loop to add items | stream.collect(Collectors.toList()) |
Collects the result into a collection like List, Set, or Map. |
| Counting | Maintain a counter in a loop | stream.count() |
Counts elements in the stream. |
| Reducing | Use loop with accumulation logic | stream.reduce((a, b) -> a + b) |
Performs reduction operations like sum, min, or max. |
| Distinct Elements | Use Set to remove duplicates |
stream.distinct() |
Removes duplicate elements. |
| Parallel Processing | Manual multi-threading | collection.parallelStream() |
Processes elements in parallel for performance (use with caution). |
| Joining Strings | Loop and string concatenation | stream.collect(Collectors.joining(", ")) |
Joins strings with delimiters. |
| Group By | Nested loops and Map logic |
Collectors.groupingBy() |
Groups elements based on a classifier function. |