JDK8 lameda表达式学习例子

lameda表达式是jdk8出的内容，作为一名老程序员，一直没接触。二次开发git上的一个开源项目，直接泪崩。于是赶紧补补课，直接上学习过程中的源码：
package xx.test.lameda;

import java.util.Arrays;
import java.util.List;
import java.util.function.Predicate;

public class LamedaMain {
    public static void main(String[] args) {

        List<String> list= Arrays.asList("danny","fancial","join","jack1");

　　　　　// 创建过滤条件 Predicate可支持and、or、xor组合
        Predicate<String> predicate = (n)->n.startsWith("j");
        Predicate<String> predicate1 = (n)->n.length()==5;

　　　　  //过滤list中字母“j”开头的元素
        System.out.println("====print start with j");
        list.stream().filter(predicate).forEach(System.out::println);

　　　　  //过滤list中字节长度为5的元素
        System.out.println("=====print length is 5");
        list.stream().filter(predicate1).forEach(System.out::println);

        //过滤list中字母“j”开头并且长度为5的元素
        System.out.println("=======print start with j and length is 5");
        list.stream().filter(predicate.and(predicate1)).forEach(System.out::println);

        //过滤list中字母“j”开头或者长度为5的元素
        System.out.println("=======print start with j or length is 5");
        list.stream().filter(predicate.or(predicate1)).forEach(System.out::println);

        //利用stream和map修改doubleList中元素的内容
        System.out.println("=======show may operation");
        List<Double> doubleList = Arrays.asList(100.0,200.0,300.0,400.0);
        doubleList.stream().map(n->n*0.2).forEach(System.out::println);

        //利用stream和reduce聚合输出
        System.out.println("========show reduce operation");
        System.out.println("sum is "+doubleList.stream().map(n->n*0.2).reduce((sum,n)->sum+n).get());

        List<Integer> integerList = Arrays.asList(100,200,300,400);
        System.out.println("max is "+integerList.stream().reduce(Integer::max).get());
        System.out.println("min is "+integerList.stream().reduce(Integer::min).get());

        System.out.println("sum is "+integerList.stream().reduce(Integer::sum).get());
    }
}