java8的新特性 | 易学教程

1.lambda表达式

替换匿名类：

比如大多匿名内部类的多行代码中仅有一行在做实际工作。

public class lambada {     //正常线程启动     public static void runSomeThing(){         Runnable runnable = new Runnable() {             public void run() {                 System.out.println("I am running");             }         };         new Thread(runnable).start();     }     //使用lambda式之后的     public static void runSomeThingByLambda(){         new Thread(() -> System.out.println("I am running")).start();      }      public static void test2(){        Runnable r = () -> System.out.println("do something.");     }     public static void main(String[] args) {      //   runSomeThing();      runSomeThingByLambda();      //   test2();     } }

List表进行迭代

// Java 8之前：    public static void List(){        List features = Arrays.asList("Lambdas", "Default Method", "Stream API", "Date and Time API");        for (Object feature : features) {            System.out.println(feature);        }    }    public static void ListNew(){        List features = Arrays.asList("Lambdas", "Default Method", "Stream API", "Date and Time API");        features.forEach(n->System.out.println(n));     }     // 使用Java 8的方法引用更方便，方法引用由::双冒号操作符标示，     // 看起来像C++的作用域解析运算符    public static void ListNew2(){        List features = Arrays.asList("Lambdas", "Default Method", "Stream API", "Date and Time API");        features.forEach(System.out::println);    }

2.什么是函数式编程

在思考问题时，使用不可变值和函数，函数对一个值进行处理，映射成另一个值。

例子

import java.util.function.Consumer;  public class CookingDemo {     //Consumer<T>用于接收一个对象进行处理但没有返回，比如接收一个人并打印他的名字     public void doTask(String materia, Consumer<String> consumer) {        consumer.accept(materia);     }     public static void main(String[] args) {         CookingDemo cookingDemo = new CookingDemo(); //        cookingDemo.doTask("蔬菜", material -> System.out.println("清洗" + material));         cookingDemo.doTask("蔬菜",material -> System.out.println("清洗" + material));         cookingDemo.doTask("蔬菜", material -> System.out.println(material + "切片"));         cookingDemo.doTask("食用油", material -> System.out.println(material + "烧热"));         cookingDemo.doTask("", material -> System.out.println("炒菜"));     } }

输出结果：

清洗蔬菜
蔬菜切片
食用油烧热
炒菜

文章来源: java8的新特性

标签

蔬菜

system

material