集合(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("alisi3",23),"nanjing");
        tm.put(new Student("blisi1",21),"beijing");
        tm.put(new Student("clisi4",24),"wuhan");
        tm.put(new Student("dlisi2",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);
        }
    }
}