Java Stream API – Complete List with Examples

A stream pipeline has a source (list.stream()), lazy intermediate operations (filter, map, sorted) and one terminal operation (toList, count, collect) that runs it. Streams don't change their source.

Name	Description	Since
`stream.filter()`	Keep only the elements that match a condition. Intermediate and lazy: nothing runs until a terminal operation.	Java 8
`stream.map()`	Transform each element with a function and return a stream of the results.	Java 8
`stream.toList()`	Collect a stream's elements into an unmodifiable List. Shorter than collect(Collectors.toList()).	Java 16
`stream.reduce()`	Combine all elements into one value with an accumulator function, starting from an identity value.	Java 8
`stream.mapToInt()`	Map to an IntStream of primitive ints, which has sum(), average(), min(), max() and summaryStatistics().	Java 8
`stream.sorted()`	Return a stream sorted by natural order or by a Comparator. The source collection is not changed.	Java 8
`stream.distinct()`	Remove duplicate elements (by equals()), keeping the first occurrence of each, in encounter order.	Java 8
`stream.limit()`	Keep at most the first n elements. skip(n) drops the first n. Together they paginate a stream.	Java 8
`stream.count()`	Return the number of elements in the stream (a long). A terminal operation.	Java 8
`stream.anyMatch()`	Return true if any element matches a condition, stopping at the first match. allMatch() and noneMatch() are similar.	Java 8
`stream.collect(Collectors.joining())`	Join a stream of strings into one string, with an optional separator, prefix and suffix.	Java 8
`stream.collect(Collectors.groupingBy())`	Group elements into a Map by a key function, optionally counting or summing each group.	Java 8

Name

Description

Since

stream.filter()

Keep only the elements that match a condition. Intermediate and lazy: nothing runs until a terminal operation.

Java 8

stream.map()

Transform each element with a function and return a stream of the results.

Java 8

stream.toList()

Collect a stream's elements into an unmodifiable List. Shorter than collect(Collectors.toList()).

Java 16

stream.reduce()

Combine all elements into one value with an accumulator function, starting from an identity value.

Java 8

stream.mapToInt()

Map to an IntStream of primitive ints, which has sum(), average(), min(), max() and summaryStatistics().

Java 8

stream.sorted()

Return a stream sorted by natural order or by a Comparator. The source collection is not changed.

Java 8

stream.distinct()

Remove duplicate elements (by equals()), keeping the first occurrence of each, in encounter order.

Java 8

stream.limit()

Keep at most the first n elements. skip(n) drops the first n. Together they paginate a stream.

Java 8

stream.count()

Return the number of elements in the stream (a long). A terminal operation.

Java 8

stream.anyMatch()

Return true if any element matches a condition, stopping at the first match. allMatch() and noneMatch() are similar.

Java 8

stream.collect(Collectors.joining())

Join a stream of strings into one string, with an optional separator, prefix and suffix.

Java 8

stream.collect(Collectors.groupingBy())

Group elements into a Map by a key function, optionally counting or summing each group.

Java 8