JAVA8自定义Lambda表达式的常见使用方法

根据使用场景不同，Lambda表达式的常见使用方法通常有三种写法。

import org.junit.Test;/** * Lambda Test * Created by Joker on 2017/8/8. */public class LambdaD {    static class Math {        private static Object execute(Integer... args) {            Integer sum = 0;            for (Integer arg : args) {                sum += arg;            }            return sum;        }    }    interface Executor {        Object execute(Integer... args);    }    private Object runExecute(Executor executor, Integer... args) {        return executor.execute(args);    }    @Test    public void test() {        System.out.println(runExecute(Math::execute, 1, 2, 3));        System.out.println(runExecute(args -> Math.execute(args), 1, 2, 3));        System.out.println(runExecute((Integer... args)-> {return args[0]+args[1]+args[2];}, 1, 2, 3));    }}

以下简单的仿照List forEach方法：

import com.springtest.colligate.Add;import org.junit.Test;import java.util.*;import java.util.function.Consumer;/** * Lambda Test * Created by Joker on 2017/8/8. */public class LambdaE {    class CustomerList<T>{        List<T> listData = new ArrayList<>();        void add(T t) {            listData.add(t);        }        void forEach(Executor<? super T> action) {            Objects.requireNonNull(action);            for (T t : listData) {                action.runAction(t);            }        }    }    interface Executor<T> {        void runAction(T t);    }    @Test    public void test(){        CustomerList<String> aaa = new CustomerList<String>();        aaa.add("WuYiFan");        aaa.add("TFBoys");        aaa.add("Angelababy");        aaa.forEach(a->{System.out.println(a);});    }}

总结：当某个类在需要接口类型构造方法时，我们可以以Lambda的形式申明该接口的实例。其本质是对传入的对象做怎样的操作。