代码训练营——TreeSet

import java.util.*;//存储自定义对象；想按照学生的年龄进行排序//TreeSet:可以对Set集合中的元素进行排序//需求：/*往TreeSet集合中存储自定义对象学生。想按照学生的年龄进行排序。记住：排序时，当主要条件相同时，一定判断次要条件。*/class TreeSetDemo{    public static void main(String[] args)    {        TreeSet ts = new TreeSet();        ts.add(new Student("lisi02",22));        ts.add(new Student("lisi03",20));        ts.add(new Student("lisi06",19));        Iterator it = ts.iterator();        while(it.hasNext())        {            Student stu = (Student)it.next();            sop(stu.getName()+"......"+stu.getAge());        }    }    public static void sop(Object obj)    {        System.out.println(obj);    }}class Student implements Comparable //该接口强制让学生具备比较性{    private String name;    private int age;    Student(String name,int age)    {        this.name = name;        this.age = age;    }    public int compareTo(Object obj)//复写比较方法    {        if(!(obj instanceof Student))            throw new RuntimeException("不是学生类");        Student stu = (Student)obj;        System.out.println(this.name+"...compareTo..."+stu.name);        if(this.age > stu.age)            return 1;         if(this.age == stu.age)         {             return this.name.compareTo(stu.name);         }            return -1;    }    public String getName()    {        return name;    }    public int getAge()    {        return age;    }}

lisi02…compareTo…lisi02
lisi03…compareTo…lisi02
lisi06…compareTo…lisi02
lisi06…compareTo…lisi03
lisi06……19
lisi03……20
lisi02……22

ts.add(new Student("lisi02",22));ts.add(new Student("lisi03",20));ts.add(new Student("lisi06",19));ts.add(new Student("lisi04",19));ts.add(new Student("lisi05",19));

lisi02…compareTo…lisi02
lisi03…compareTo…lisi02
lisi06…compareTo…lisi02
lisi06…compareTo…lisi03
lisi04…compareTo…lisi03
lisi04…compareTo…lisi06
lisi05…compareTo…lisi03
lisi05…compareTo…lisi06
lisi05…compareTo…lisi04
lisi04……19
lisi05……19
lisi06……19
lisi03……20
lisi02……22