Stream流的收集操作

package LambdaTest.LambdaTest06;

import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * FileName: StreamEndedDemo
 * Author:   lps
 * Date:     2022/4/10 14:00
 * Sign:刘品水 Q：1944900433
 * <p>
 * <R,A> R collect(Collector<? super T,A,R> collector)
 * 执行 mutable reduction操作对元素的使用 Collector流。
 * <R> R collect(Supplier<R> supplier, BiConsumer<R,? super T> accumulator, BiConsumer<R,R> combiner)
 * 执行该流的元素 mutable reduction操
 */
public class StreamEndedDemo {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("刘品水");
        list.add("张伟");
        list.add("刘强军");
        list.add("朱迁民");

        //得到名字为三个字的流
        Stream<String> threelist = list.stream().filter(s -> s.length() == 3);
        //把此数据收集到list中遍历
        List<String> names = threelist.collect(Collectors.toList());
        for (String name : names) {
            System.out.println(name);
        }
        System.out.println("=======");

        HashSet<Integer> set1 = new HashSet<>();
        set1.add(10);
        set1.add(12);
        set1.add(20);
        set1.add(22);
        set1.add(29);
        //得到大于18的流
        Stream<Integer> setstream = set1.stream().filter(age -> age > 18);
        //将此数据收集到set集合并遍历
        Set<Integer> age = setstream.collect(Collectors.toSet());
        for (Integer a : age) {
            System.out.println(a);
        }
        System.out.println("=======");

        String[] strArray = {"刘品水,21", "张伟,20", "朱迁民,22", "刘子衿,3"};
        //得到年纪大于20的流
        Stream<String> arraystream = Stream.of(strArray).filter(s -> Integer.parseInt(s.split(",")[1]) > 20);
        //把上面的内容 收集到map集合当中 姓名做键 年龄做值
        Map<String, Integer> map = arraystream.collect(Collectors.toMap(s -> s.split(",")[0],
                s -> Integer.parseInt(s.split(",")[1])));
        Set<String> keyset = map.keySet();
        for (String key : keyset) {
            Integer value = map.get(key);
            System.out.println(key + "," + value);

        }


    }
}