Add more stream examples

winterbe · winterbe · commit 8b960948feb0 · 2014-07-21T08:21:00.000+02:00
diff --git a/src/com/winterbe/java8/Streams5.java b/src/com/winterbe/java8/Streams5.java
@@ -1,6 +1,6 @@
 package com.winterbe.java8;
 
-import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Stream;
 
@@ -12,20 +12,16 @@
 public class Streams5 {
 
     public static void main(String[] args) {
-        List<String> stringCollection = new ArrayList<>();
-        stringCollection.add("ddd2");
-        stringCollection.add("aaa2");
-        stringCollection.add("bbb1");
-        stringCollection.add("bbb3");
-        stringCollection.add("ccc");
+        List<String> strings =
+            Arrays.asList("d2", "a2", "b1", "b3", "c");
 
-//        test1(stringCollection);
-//        test2(stringCollection);
-//        test3(stringCollection);
-//        test4(stringCollection);
-        test5(stringCollection);
-//        test6(stringCollection);
-//        test7(stringCollection);
+//        test1(strings);
+//        test2(strings);
+//        test3(strings);
+//        test4(strings);
+//        test5(strings);
+        test6(strings);
+//        test7(strings);
     }
 
     // stream has already been operated upon or closed
@@ -42,15 +38,14 @@ private static void test7(List<String> stringCollection) {
     private static void test6(List<String> stringCollection) {
         stringCollection
             .stream()
-            .filter(s -> {
-                System.out.println("filter: " + s);
-                return s.startsWith("a");
-            })
             .map(s -> {
-                System.out.println("map:    " + s);
+                System.out.println("map:      " + s);
                 return s.toUpperCase();
             })
-            .anyMatch(s -> s.startsWith("A"));
+            .anyMatch(s -> {
+                System.out.println("anyMatch: " + s);
+                return s.startsWith("A");
+            });
     }
 
     private static void test5(List<String> stringCollection) {
diff --git a/src/com/winterbe/java8/Streams8.java b/src/com/winterbe/java8/Streams8.java
@@ -0,0 +1,39 @@
+package com.winterbe.java8;
+
+import java.util.Arrays;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+/**
+ * @author Benjamin Winterberg
+ */
+public class Streams8 {
+
+    public static void main(String[] args) {
+        Arrays.asList("a1", "a2", "a3")
+            .stream()
+            .findFirst()
+            .ifPresent(System.out::println);
+
+        Stream.of("a1", "a2", "a3")
+            .map(s -> s.substring(1))
+            .mapToInt(Integer::parseInt)
+            .max()
+            .ifPresent(System.out::println);
+
+        IntStream.range(1, 4)
+            .mapToObj(i -> "a" + i)
+            .forEach(System.out::println);
+
+        Arrays.stream(new int[] {1, 2, 3})
+            .map(n -> 2 * n + 1)
+            .average()
+            .ifPresent(System.out::println);
+
+        Stream.of(1.0, 2.0, 3.0)
+            .mapToInt(Double::intValue)
+            .mapToObj(i -> "a" + i)
+            .forEach(System.out::println);
+
+    }
+}
diff --git a/src/com/winterbe/java8/Streams9.java b/src/com/winterbe/java8/Streams9.java
@@ -0,0 +1,21 @@
+package com.winterbe.java8;
+
+import java.util.Arrays;
+
+/**
+ * @author Benjamin Winterberg
+ */
+public class Streams9 {
+
+    public static void main(String[] args) {
+        Arrays.asList("a1", "a2", "b1", "c2", "c1")
+            .stream()
+            .filter(s -> s.startsWith("c"))
+            .map(String::toUpperCase)
+            .sorted()
+            .forEach(System.out::println);
+
+        // C1
+        // C2
+    }
+}
