Create a Stream

There are several ways to create a stream in Java 8. Here are the main methods:

1. From a Collection:

   List<String> list = Arrays.asList("a", "b", "c");
   Stream<String> stream = list.stream();
   

2. From an array:

   String[] array = {"a", "b", "c"};
   Stream<String> stream = Arrays.stream(array);
   

3. Using Stream.of():

   Stream<String> stream = Stream.of("a", "b", "c");
   

4. Using Stream.generate():

   Stream<Double> randomNumbers = Stream.generate(Math::random);
   

5. Using Stream.iterate():

   Stream<Integer> evenNumbers = Stream.iterate(0, n -> n + 2);
   

6. From a file (lines):

   Stream<String> lines = Files.lines(Paths.get("file.txt"));
   

7. From a string:

   IntStream streamOfChars = "abc".chars();
   

8. Using Stream.builder():

   Stream<String> stream = Stream.<String>builder().add("a").add("b").add("c").build();
   

9. From a range of integers:

   IntStream range = IntStream.range(1, 5); // 1, 2, 3, 4
   IntStream rangeClosed = IntStream.rangeClosed(1, 5); // 1, 2, 3, 4, 5
   

10. Parallel streams from collections:

    Stream<String> parallelStream = list.parallelStream();
    

These are the most common ways to create streams in Java 8. Each method has its use cases depending on the data source and the specific requirements of our application.