java streams example

1the Stream API is used to process collections
2of objects. A stream is a sequence of objects
3that supports various methods which can be
4pipelined to produce the desired result.
5  It is very similar to build().perform() 
6  method in Actions class. It is chaining
7  some operations in an order.
8
9The features of Java stream are:
10- A stream is not a data structure instead
11it takes input from the Collections, 
12Arrays or I/O channels.
13- Streams don’t change the original data
14structure, they only provide the result
15as per the pipelined methods.
16- Each intermediate operation is lazily
17executed and returns a stream as a result,
18hence various intermediate operations
19can be pipelined. Terminal operations mark
20the end of the stream and return the result.
21
22Different Operations On Streams:
23
24map ==> The map method is used to return a
25stream consisting of the results of applying
26the given function to the elements of this stream.
27List number = Arrays.asList(2,3,4,5);
28List square = number.stream().map(x->x*x).collect(Collectors.toList());
29
30filter ==> The filter method is used to
31select elements as per the Predicate passed as argument.
32List names = Arrays.asList("Reflection","Collection","Stream");
33List result = names.stream().filter(s->s.startsWith("S")).collect(Collectors.toList());
34
35sorted ==> The sorted method is used to sort the stream.
36List names = Arrays.asList("Reflection","Collection","Stream");
37List result = names.stream().sorted().collect(Collectors.toList());
38
39ArrayList<String> list3 = new ArrayList(Arrays.asList("monkey", "donkey","onion"));
40List<String> list4 = list3.stream().filter(each->!"onion".equals(each)).collect(Collectors.toList());
41System.out.println(list4);
42
43static String reverse(String word){
44    return Arrays.stream(word.split("")).reduce("", (x,y) -> y+x );
45}

1public class StreamBuilders 
2{
3     public static void main(String[] args)
4     {
5         Stream<Integer> stream = Stream.of( new Integer[]{1,2,3,4,5,6,7,8,9} );
6         stream.forEach(p -> System.out.println(p));
7     }
8}
9

1stream().of(1,2,3,4,5).forEach(System.out::print);
2// Output : 12345