集合(TreeMap练习)

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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);        }    }}

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