stream

Author: MyHerux

src/main/java/com/xu/java8/Optional/Optional.md

@@ -1,35 +1,44 @@
 ##optional类
+
 - **创建一个空Optional对象**
-输出的是一个空的optional对象
-```
- Optional<String> optional = Optional.empty();
- System.out.println(optional);
- ##:Optional.empty
-```
+
+    输出的是一个空的optional对象
+
+    ```
+    Optional<String> optional = Optional.empty();
+    System.out.println(optional);
+    ##:Optional.empty
+    ```
+
 - **创建一个非空Optional对象**
-如果person是null，将会立即抛出,而不是访问person的属性时获得一个潜在的错误
-
-```
- Person person = new Person("xu","hua");
- Optional<Person> optional2 = Optional.of(person);
- System.out.println(optional2);
- System.out.println(optional2.get());
- System.out.println(optional2.get().firstName);
- ##:Optional[xuhua]
-    xuhua
-    xu
-```
+
+    如果person是null，将会立即抛出,而不是访问person的属性时获得一个潜在的错误
+
+    ```
+    Person person = new Person("xu","hua");
+    Optional<Person> optional2 = Optional.of(person);
+    System.out.println(optional2);
+    System.out.println(optional2.get());
+    System.out.println(optional2.get().firstName);
+    ##:Optional[xuhua]
+       xuhua
+       xu
+    ```
+
 - **判断对象是否存在**
-```
- System.out.println(optional.isPresent());
- System.out.println(optional2.isPresent());
- ##:false
-    true
-```
+
+    ```
+    System.out.println(optional.isPresent());
+    System.out.println(optional2.isPresent());
+    ##:false
+       true
+    ```
+
 - **如果Optional为空返回默认值**
-```
- System.out.println(optional.orElse("fallback"));
- optional.ifPresent(System.out::println);
- ##:fallback
-    xuhua
-```
+
+    ```
+    System.out.println(optional.orElse("fallback"));
+    optional.ifPresent(System.out::println);
+    ##:fallback
+       xuhua
+    ```