add java8 foreach

hellokaton · hellokaton · commit 40fcfe41a8f5 · 2015-12-01T10:17:53.000+08:00
diff --git a/README.md b/README.md
@@ -27,7 +27,7 @@ jb is `java book`，这里记录了一些我的技术摘要，本项目的目的
 
 1. [Java8简明教程](java8/java8-guide.md)
 2. Java8 Lambda
-3. Java8 Foreach
+3. [Java8 Foreach](java8/foreach.md)
 4. Java8 Stream
 
 ## Hexo搭建博客
diff --git a/java8/foreach.md b/java8/foreach.md
@@ -0,0 +1,92 @@
+# java8 foreach
+
+在这篇文章中我将向你演示如何使用Java8中的`foreach`操作`List`和`Map`
+
+### 1. Foreach操作Map
+1.1 正常方式遍历Map
+```java
+Map<String, Integer> items = new HashMap<>();
+items.put("A", 10);
+items.put("B", 20);
+items.put("C", 30);
+items.put("D", 40);
+items.put("E", 50);
+items.put("F", 60);
+
+for (Map.Entry<String, Integer> entry : items.entrySet()) {
+	System.out.println("Item : " + entry.getKey() + " Count : " + entry.getValue());
+}
+```
+
+<!--more-->
+
+1.2 使用Java8的`foreach`+`lambda`表达式遍历Map
+```java
+Map<String, Integer> items = new HashMap<>();
+items.put("A", 10);
+items.put("B", 20);
+items.put("C", 30);
+items.put("D", 40);
+items.put("E", 50);
+items.put("F", 60);
+
+items.forEach((k,v)->System.out.println("Item : " + k + " Count : " + v));
+
+items.forEach((k,v)->{
+	System.out.println("Item : " + k + " Count : " + v);
+	if("E".equals(k)){
+		System.out.println("Hello E");
+	}
+});
+```
+
+###2. Foreach操作List
+2.1 普通方式循环List
+```java
+List<String> items = new ArrayList<>();
+items.add("A");
+items.add("B");
+items.add("C");
+items.add("D");
+items.add("E");
+
+for(String item : items){
+	System.out.println(item);
+}
+```
+2.2 在Java8中使用`foreach`+`lambda`表达式遍历List
+```java
+List<String> items = new ArrayList<>();
+items.add("A");
+items.add("B");
+items.add("C");
+items.add("D");
+items.add("E");
+
+//lambda
+//Output : A,B,C,D,E
+items.forEach(item->System.out.println(item));
+	
+//Output : C
+items.forEach(item->{
+	if("C".equals(item)){
+		System.out.println(item);
+	}
+});
+	
+//method reference
+//Output : A,B,C,D,E
+items.forEach(System.out::println);
+
+//Steam and filter
+//Output : B
+items.stream()
+	.filter(s->s.contains("B"))
+	.forEach(System.out::println);
+```
+
+参考资料：
+1. [Java 8 Iterable forEach JavaDoc](https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html#forEach-java.util.function.Consumer-)
+2. [Java 8 forEach JavaDoc](https://docs.oracle.com/javase/8/docs/api/java/util/Map.html#forEach-java.util.function.BiConsumer-)
+
+欢迎star开源web框架Blade：[http://github.com/biezhi/blade](http://github.com/biezhi/blade)
