ArrayList 多关键字排序

小鱼儿 2022-03-12 13:37 167阅读 0赞

ArrayList里面的对象实现 Comparable接口

// User.java 待排序的对象 ，实现了Comparable接口
    public class User implements Comparable{ 
    
        private String name;
        private String pass;
        private int age;
    
        public String getName() { 
            return name;
        }
    
        public String getPass() { 
            return pass;
        }
    
        public void setName(String name) { 
            this.name = name;
        }
    
        public void setPass(String pass) { 
            this.pass = pass;
        }
    
        public int getAge() { 
            return age;
        }
    
        public void setAge(int age) { 
            this.age = age;
        }
    
        @Override
        public int compareTo(Object o) { 
            User user = (User) o;
            if (this.age > user.age){ 
                return 1;
            }else if (this.age < user.age){ 
                return -1;
            }else { 
                return this.name.compareTo(user.name);
            }
        }
    }
    // Demo.java 测试程序
    
    public class Demo { 
    
    
        public static void main(String[] args) { 
            List<User> users = new ArrayList<>();
            int lastAge = -1;
            for (int i = 0; i < 20; i++) { 
                User user = new User();
                if (lastAge==-1){ 
                    int number = (int) (Math.random() * 100);
                    user.setAge(number);
                    lastAge = number;
                }else { 
                    user.setAge(lastAge);
                    lastAge = -1;
                }
                int n = 20 - i;
                user.setName(n + "haha");
                user.setPass(n + "");
                users.add(user);
            }
            Collections.sort(users);
            for (int i = 0; i < 20; i++) { 
                User user = users.get(i);
                System.out.println(user.getName() + " " + user.getAge() + " " + user.getPass());
            }
        }
    }

调用排序，只需要Collections.sort(users); 即可。运行结果：略