1眠冈、Lambda表達(dá)式簡(jiǎn)單說(shuō)就是一個(gè)方法

2已慢、它可以作為參數(shù)在方法見傳遞

3入挣、但只能在使用了FunctionalInterface的地方

4移宅、FunctionalInterface是單個(gè)方法的接口虎忌，且使用了@FunctionalInterface的注解

5泡徙、Lambda的好處是語(yǔ)法簡(jiǎn)潔，同時(shí)在多核CPU下運(yùn)行效率高

6膜蠢、Lambda表達(dá)式的語(yǔ)法
基本語(yǔ)法:
(parameters) -> expression或
(parameters) ->{ statements; }

實(shí)例：
一：runnable接口符合Lambda的要求（3和4點(diǎn)就是使用Lambda表達(dá)式的基本要求）

Runnable.class

public class LearnLambda1 {
    public static void main(String [] args){
        for(int i = 0; i<1000; i++)
            new Thread(()->
            System.out.println("I am thread "+Thread.currentThread().getId())).start();
    }
}

二堪藐、List.forEach(Consumer c)中的Consumer接口也是只有一個(gè)方法莉兰，并且使用了@FunctionalInterface的注解

public class LearnLambda2 {
    public static void main(String [] args){
        List<Person> persons = new ArrayList<Person>();
        persons.add(new Person("張三","化學(xué)",60));
        persons.add(new Person("李四","生物",78));
        persons.add(new Person("王五","物理",69));
        persons.add(new Person("錢六","計(jì)算機(jī)",83));
        persons.add(new Person("趙七","英語(yǔ)",90));
        
        persons.forEach((Person p)->System.out.println(p.name));
        System.out.println();
        persons.forEach((Person p)->System.out.println(p.name + ":" + p.department));
        System.out.println();
        persons.forEach((Person p)->System.out.println(p.name + ":" + p.score));
    }
}
public class Person {
    public String name;
    public String department;
    public int score;
    public Person(String name, String department, int score) {
        this.name = name;
        this.department = department;
        this.score = score;
    }
}

三、Predicate接口也是也是只有一個(gè)方法礁竞，并且使用了@FunctionalInterface的注解(接口詳細(xì)信息請(qǐng)看API)

public class LearnLambda3 {
    public static void main(String [] args){
        List<Person> persons = new ArrayList<Person>();
        persons.add(new Person("張三","化學(xué)",60));
        persons.add(new Person("李四","生物",78));
        persons.add(new Person("王五","物理",69));
        persons.add(new Person("錢六","計(jì)算機(jī)",83));
        persons.add(new Person("趙七","化學(xué)",90));
//      filterPrint(persons,(Person p)->p.department.equals("化學(xué)"));
        filterPrint(persons,(Person p)->p.score>70);
    }
    public static void filterPrint(List<Person> persons,Predicate<Person> predicate){
        for(Person p : persons){
            if(predicate.test(p))
                System.out.println(p.name);
        }
    }
}

四糖荒、當(dāng)然我們可以自定義接口來(lái)使用lambda

@FunctionalInterface
interface Studey{
    void studing();
}
public class LearnLambda4 {
    public static void doSomething(Studey study){//可以有多個(gè)參數(shù)，方法內(nèi)容也可以自定義
        study.studing();
    }
    public static void main(String [] args){
        doSomething(()->System.out.println("我正在學(xué)習(xí)lambda"));
    }
}