java Stream

一、Stream

1、概述

2、Stream流使用过程

示例图：

3、 Stream流的常见生成方式

示例：

package itbianma01;

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

public class Demo {
    public static void main(String[] args) {
        //方式一：Collection体系的集合可以使用默认方法stream生成流
        List<String> list = new ArrayList<>();
        Stream<String> listStream = list.stream();

        Set<String> set = new HashSet<>();
        Stream<String> setStream = set.stream();

        //方式二：map体系的集合间接地生成流
        Map<String, Integer> map = new HashMap<>();
        Stream<String> keyStream = map.keySet().stream();
        Stream<Integer> valueStream = map.values().stream();
        Stream<Map.Entry<String, Integer>> entryStream = map.entrySet().stream();

        //方式三：数组
        String[] array = {"java", "hello", "world"};
        Stream<String> strArrayStream = Stream.of(array);
        Stream<String> strArrayStream1 = Stream.of("java", "hello", "world");
        Stream<Integer> intStream = Stream.of(10, 20, 30);
    }
}