JDK8之Collectors之分组

1、建立一个实体类
 public class Person {
    private String color;
    private Integer grice;

    public Person() {
    }

    public Person(String color, Integer grice) {
        this.color = color;
        this.grice = grice;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public Integer getGrice() {
        return grice;
    }

    public void setGrice(Integer wight) {
        this.grice = wight;
    }

    @Override
    public String toString() {
        return "Person{" +
                "color='" + color + '\'' +
                ", grice=" + grice +
                '}';
    }
}

2、测试一

List<Person> lists = Arrays.asList(
        new Person("白色",1),
        new Person("白色",2),
        new Person("红色",3),
        new Person("红色",4),
        new Person("黑色",5)
        );
（1）获取白色数据
List<Person> griceList = lists.stream().filter(t -> t.color.equals("白色")).collect(Collectors.toList());
（2）根据颜色进行分组
Map<String,List<Person>> groupMap = lists.stream().collect(Collectors.groupingBy(Person::getColor));
System.out.println("griceList ="+griceList.toString());
System.out.println("groupMap ="+groupMap.toString());