Functional Programming with lambda in Java 8

Here are some very good tutorials and a simple sample: https://leanpub.com/whatsnewinjava8/read Understanding Java 8 Stream Performance from Maurice Naftalin When to use parallel streams and Java Doc Extra features supported by AbacusUtil:

Stream is supported for primitive type except boolean: CharStream, ByteStream, ShortStream, IntStream, LongStream, FloatStream, DoubleStream and Stream. More convenient APIs are provided by: Collectors and Stream Integrated with different data structures: DataSet, Multimap, Multiset and primitive list. Faster Java8 stream implementation for array/collection. Here is the performance test result: stream_performance_test_result.txt by below code:

With the support of Lambda/Stream and DataSet, AbacusUtil provides a set of VERY POWERFUL APIs to process/analyze data.

Stream.of("abc", "123", "ab123").filter(str -> str.startsWith("a")).forEach(N::println);
// abc
// ab123

List<String> strs = N.asList("Hello Java", "I LIKE Functional Programming");

// average length of words in the strings.
Stream.of(strs).flatMap2(str -> str.split(" ")).collect(Collectors.averagingDouble(str -> str.length()));
// 5.833333333333333

// count the characters in upper case.
Stream.of(strs).flatMapToChar(str -> Stream.from(str.toCharArray())).filter(ch -> Character.isUpperCase(ch)).count();
// 9