Add more stream examples

Author: winterbe

src/com/winterbe/java8/Streams10.java

@@ -0,0 +1,48 @@
+package com.winterbe.java8;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+/**
+ * @author Benjamin Winterberg
+ */
+public class Streams10 {
+
+ static class Person {
+ String name;
+ int age;
+
+ Person(String name, int age) {
+ this.name = name;
+ this.age = age;
+ }
+
+ @Override
+ public String toString() {
+ return name;
+ }
+ }
+
+ public static void main(String[] args) {
+ test1();
+ }
+
+ private static void test1() {
+ List<Person> persons =
+ Arrays.asList(
+ new Person("Max", 18),
+ new Person("Peter", 23),
+ new Person("Brenda", 23),
+ new Person("David", 12));
+
+ Map<Integer, List<Person>> personsByAge = persons
+ .stream()
+ .collect(Collectors.groupingBy(p -> p.age));
+
+ personsByAge
+ .forEach((age, p) -> System.out.format("age: %s; persons: %s\n", age, p));
+ }
+
+}