TreeMap的练习（该例需要上例的学生类）

import java.util.*;
class TreeMapTest 
{
    public static void main(String[] args) 
    {
        TreeMap<Student,String> tm=new TreeMap<Student,String>(new mycompare());  //new TreeMap<Student,String>(); 不带参数的构造函数，Student中 已经写了compareTo 方法比较
        tm.put(new Student("lisi01",25),"beijing");
        tm.put(new Student("lisi02",22),"tianjing");
        tm.put(new Student("lisi02",22),"dongjing"); //put的特点：后者会覆盖前面的value。
        tm.put(new Student("lisi04",20),"shanghai");
        tm.put(new Student("lisi03",23),"xiamen");

         Set<Student> ks=tm.keySet();
        for(Iterator<Student> it=ks.iterator();it.hasNext();)
        {
            Student stu=it.next();
            String    address=tm.get(stu);
            System.out.println(stu.getName()+".."+stu.getAge()+".."+address);
        }
        /*
        Set<Map.Entry<Student,String>> et=tm.entrySet();
        for(Iterator<Map.Entry<Student,String>> it=et.iterator();it.hasNext();)   //Iterator 泛型别忘了<Map.Entry<Student,String>>
        {            
            Map.Entry<Student,String> me=it.next();
            String address=me.getValue();
            Student info =me.getKey();
            System.out.println(info.getName()+".."+info.getAge()+".."+address);
        }    */
    }
}
class mycompare implements Comparator<Student>
{
    public int compare(Student s1,Student s2)
    {
//        Student s1=(Student)o1;
//        Student s2=(Student)o2;
        int num= new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
        if(num==0)
        {
            return  s1.getName().compareTo(s2.getName()) ;
        }
        return num;
    }
}