使用Java 8 Stream list排序

使用Java 8 Stream list排序

先看实体类

public class UserSimple  {
    private int id;
    private String name;

    public UserSimple(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "UserSimple{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

1.按id 排序

 //按照id来排序
        List<UserSimple> usersimple =new ArrayList<>();
        usersimple.add(new UserSimple(1,"10,1"));
        usersimple.add(new UserSimple(5,"10,2"));
        usersimple.add(new UserSimple(2,"10,5"));
        usersimple.add(new UserSimple(7,"10,7"));
        usersimple.add(new UserSimple(3,"10,3"));
        List<UserSimple> usersimple1 =new ArrayList<>();
        usersimple1 = usersimple.stream().sorted(Comparator.comparingInt(UserSimple::getId))
                .collect(Collectors.toList());
        usersimple1.forEach(System.out::println);

2. 按 name 排序

（取10,？中的？ 进行排序）

public static void main(String[] args) {
        List<UserSimple> usersimple =new ArrayList<>();
        usersimple.add(new UserSimple(1,"10,1"));
        usersimple.add(new UserSimple(5,"10,2"));
        usersimple.add(new UserSimple(2,"10,5"));
        usersimple.add(new UserSimple(7,"10,7"));
        usersimple.add(new UserSimple(3,"10,3"));
         List<UserSimple> usersimple2 =new ArrayList<>();
        usersimple2 = usersimple.stream().sorted((a,b)->{
           String[] v1 = a.getName().split(",");
           String[] v2 = b.getName().split(",");
           if(v2.length !=2){
               return -1;
           }
            if(v1.length !=2){
                return -1;
            }
            return Str2Int(v1[1]) - Str2Int(v2[1]);
        }).collect(Collectors.toList());
        System.out.println("=====");
        usersimple2.forEach(System.out::println);
        }
public static int Str2Int(String strVal) {
        if (strVal == null)
            return 0;

        int nVal = 0;
        try {
            nVal = Integer.valueOf(strVal);
        } catch (Exception e) {
            return 0;
        }

        return nVal;
    }