Java 高阶函数的简单使用：map，reduce，filter，sorted

package cn.test;

import java.util.ArrayList;
import java.util.IntSummaryStatistics;
import java.util.stream.Collectors;

import org.junit.Test;

public class Test1 {
    static ArrayList a = new ArrayList();
    static ArrayList b = new ArrayList();
    static{
        a.add(4);
        a.add(3);
        a.add(2);
        a.add(1);
        a.add(6);
        a.add(7);
        a.add(8);
        a.add(5);
        a.add(9);
        a.add(0);
    }
    @Test
    public void testMap(){
        System.out.println("mmmmmmmmmmmmmmmmmmmmmmmmmmm");
        a.stream().map((x)->(x+100)).forEach((num)->{System.out.print(num+",");});
        a.forEach(System.out::print);
        System.out.println();
    }
    @Test
    public void testMap1(){
        System.out.println("mmmmmmmmmmmmmmmmmmmmmmmmmmm1111");
        b = (ArrayList) a.stream().map((x)->(x+100)).collect(Collectors.toList());
        b.forEach(System.out::print);
        System.out.println();
    }

    @Test
    public void testReduce(){
        System.out.println("rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr");
        int b = a.stream().reduce((x,y)->x+y).get();
        System.out.println("sum = "+b);
        System.out.println();
    }
    @Test
    public void testFilter(){
        System.out.println("ffffffffffffffffffffffff");
        b = (ArrayList) a.stream().filter((y)->y%2!=0).collect(Collectors.toList());
        b.forEach((x)->System.out.print(x+","));
        System.out.println();
    }
    @Test
    public void testSort(){
        System.out.println("ssssssssssssssssssssssssssss");
        b = (ArrayList) a.stream().sorted().collect(Collectors.toList());
        b.forEach((x)->System.out.print(x+","));
        System.out.println();
    }
    @Test
    public void testSort1(){
        System.out.println("ssssssssssssssssssssssssssss11111111");
        b = (ArrayList) a.stream().sorted((x,y)->{
            if(x>y){
                return -1;
            }else if(x==y){
                return 0;
            }else{
                return 1;
            }
        }).collect(Collectors.toList());
        b.forEach((x)->System.out.print(x+","));
        System.out.println();
    }
    @Test
    public void testSort2(){
        System.out.println("ssssssssssssssssssssssssssss2222222222222222");
        b = (ArrayList) a.stream().sorted((x,y)->(x.compareTo(y))).collect(Collectors.toList());
        b.forEach((x)->System.out.print(x+","));
        System.out.println();
    }
    @Test
    public void testSort3(){
        System.out.println("ssssssssssssssssssssssssssss3333333333333333333");
        b = (ArrayList) a.stream().sorted((x,y)->(-x.compareTo(y))).collect(Collectors.toList());
        b.forEach((x)->System.out.print(x+","));
        System.out.println();
    }

    @Test
    public void testSummaryStatistics(){
        System.out.println("================SummaryStatistics====================");
        IntSummaryStatistics statistics = a.stream().mapToInt((x)->x).summaryStatistics();
        System.out.println("最大值:"+statistics.getMax());
        System.out.println("最小值:"+statistics.getMin());
        System.out.println("平均值:"+statistics.getAverage());
        System.out.println("总数:"+statistics.getCount());
        System.out.println("和:"+statistics.getSum());
    }
    @Test
    public void testParallelStream(){
        System.out.println("*******************ParallelStream**********************");
        //以下使用有错误
//      IntStream intStream = a.parallelStream().mapToInt((x)->x);
//      System.out.println("最大值:"+intStream.max());
//      System.out.println("最小值:"+intStream.min());
//      System.out.println("平均值:"+intStream.average());
//      System.out.println("总数:"+intStream.count());
//      System.out.println("和:"+intStream.sum());
        System.out.println("最大值:"+a.parallelStream().mapToInt((x)->x).max());
        System.out.println("最小值:"+a.parallelStream().mapToInt((x)->x).min());
        System.out.println("平均值:"+a.parallelStream().mapToInt((x)->x).average());
        System.out.println("总数:"+a.parallelStream().mapToInt((x)->x).count());
        System.out.println("和:"+a.parallelStream().mapToInt((x)->x).sum());
    }
}