Add more stream examples

winterbe · winterbe · commit 131d87df4633 · 2014-07-21T09:45:34.000+02:00
diff --git a/src/com/winterbe/java8/Streams10.java b/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));
+    }
+
+}
