集合框架——TreeMap练习

/*
需求：对学生对象的年龄进行升序排序。

因为数据是以键值对形式存在的。
所以要使用可以排序的Map集合。TreeMap。
*/
import java.util.*;

class StuNameComparator implements Comparator<Student>
{
public int compare(Student s1,Student s2)
{
int num = s1.getName().compareTo(s2.getName());
if(num==0)
return new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));

return num;
}
}


class  MapTest2
{
public static void main(String[] args) 
{
TreeMap<Student,String> tm = new TreeMap<Student,String>(new StuNameComparator());

tm.put(new Student("blisi3",23),"nanjing");
tm.put(new Student("lisi1",21),"beijing");
tm.put(new Student("alisi4",24),"wuhan");
tm.put(new Student("lisi1",21),"tianjin");
tm.put(new Student("lisi2",22),"shanghai");


Set<Map.Entry<Student,String>> entrySet = tm.entrySet();

Iterator<Map.Entry<Student,String>> it = entrySet.iterator();

while(it.hasNext())
{
Map.Entry<Student,String> me = it.next();

Student stu = me.getKey();
String addr = me.getValue();
System.out.println(stu+":::"+addr);
}
}
}