TreeSet结合存入元素的两种方式 - 黑马程序员技术交流社区

import java.util.*;
/*
需求：TreeSet集合两种存入元素的方法
*/
class TreeSetTest
{
public static void main(String[] args)
{
TreeSet ts=new TreeSet(new Mycompare());
ts.add(new Student("张三",29));
ts.add(new Student("李四",29));
ts.add(new Student("王五",31));
ts.add(new Student("张三",29));
ts.add(new Student("赵六",30));
ts.add(new Student("李四",29));
sop(ts);
}
public static void sop(Object obj){
System.out.println(obj);
}
}
//第一种：让需要存入 TreeSet集合的元素实现Comparable，从而具备比较性
class Student implements Comparable
{
private String name;
private int age;
Student(String name,int age){
this.name=name;
this.age=age;
}
public String getName(){
return name;
}
public int getAge(){
return age;
}
//复写compareTo()方法，定义元素的比较方式
public int compareTo(Object obj){
if(!(obj instanceof Student))
throw new RuntimeException("数据类型不符");
Student stu=(Student)obj;
int num=this.name.compareTo(stu.name);
if(num==0)
return new Integer(this.age).compareTo(stu.age);
return num;
}
//自定义equals方法，判断两个Person对象是否相同
public boolean equals(Object obj){
if(!(obj instanceof Student))
return false;
Student stu=(Student)obj;
return this.getName().equals(stu.getName())&&this.age==stu.age;
}
public String toString(){
return this.name+":"+this.age;
}
}
//第二种方式：自定义比较器，将比较器对象传给TreeSet集合对象，使集合具备对元素的比较功能
class Mycompare implements Comparator
{
public int compare(Object obj1,Object obj2){
Student stu1=(Student)obj1;
Student stu2=(Student)obj2;
int num=new Integer(stu1.getAge()).compareTo(stu2.getAge());
if(num==0)
return stu1.getName().compareTo(stu2.getName());
return num;
}
}

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