TreeSet红黑树结构

存进去无序,但是取出来时会有排序(红黑树算法)这个集合在SortedSet接口下

对象就必须实现Comparable接口,和其下的compareTo方法

//实现Comparable接口并泛型
public class Student implements Comparable{

    public String name;
    public int age;
    public char sex;

    public Student(){}

    public Student(String name,int age,char sex){
        this.age = age;
        this.name = name;
        this.sex = sex;
    }

如果对象的全部属性都相同,就代表是重复元素

@Override
public int compareTo(Student o) {
    int name = this.name.compareTo(o.name);
    int age = this.age - o.age;
    int sex = this.sex - o.sex;

    
    return name == 0 ? age - sex : name;
}

package com.li.changGe.collections.setGather;

import com.li.changGe.pojo.Student;

import java.util.Set;
import java.util.TreeSet;

public class TreeSetDemo01 {

  public static void main(String[] args) {
      Set set = new TreeSet();

      Student student = new Student("长歌",18,'女');
      Student student1 = new Student("世民",22,'男');
      Student student2 = new Student("则天",20,'女');

      set.add(student);
      set.add(student1);
      set.add(student2);
//----------------------------------------------------------------
      //重写compareTo()后按照属性来判重
      set.add(new Student("长歌",18,'女'));

      //重写前长度4,重写后3
      System.out.println("长度:"+set.size()+"n"+set);

  }

}