demo01 - Stream/Optional

• Stream<Double> // Arrays.stream();
  • skip()
  • limit()
• Stream<String> // list.stream();

list.add("A sequence of elements supporting sequential and parallel aggregate operations.");
list.add("In addition to Stream, which is a stream of object references, there are primitive specializations for IntStream.");
list.add("To perform a computation, stream operations are composed into a stream pipeline.");

• map(lowercase)
• flatMap()
• Stream<Integer>
  • reduce() (use Set (TreeSet), set.stream()) (Collections.addAll) (convert set to Stream first and then use reduce)
• Stream<Integer> strm = Stream.iterate();
  • print table of number
• Stream<Integer> strm = Stream.generate(() -> r.nextInt(100));
  • random number stream (Random r = new Random)
• collect in a list (Collectors.toList)
• collect (distinct) in a set
• Stream of primitive values
  • // primitive streams are more efficient -- because no boxing/unboxing done for each arithmetic
  • Create a stream of wrapper class (use Stream.iterate(1, i -> i + 1))
  • try Creating stream of primitive (Compiler Error)
  • IntStream strm = IntStream.of(1,2,3,4,5);

demo02 - Method references

// lambda expr = short-hand implementation of SAM (functional interface)
// method ref = short-hand of lambda expr

• static method reference

  // static method of a class --> ClassName.method(arg1, arg2); i.e. static method called on ClassName

• non-static method reference

  // non-static method of a class --> arg1.method(arg2); i.e. non-static method called on arg1

• object method reference

  // non-static method to call on obj --> obj.method(arg); i.e. non-static method called on given object

• constructor reference

  // param-less constructor is called after creating object of given class