黑马程序员-JavaAPI-16天-7(TreeMap练习)

package string.test;

import java.util.Comparator;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

/*
 * 
 * 需求：对学生对象的年龄经行升序排序
 * 
 * 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
 * 
 * 定义一个对Student的排序类StuNameComparator 要求安名称进行排序 如果名称相同就按年龄进行排序
 */
class StuNameComparator implements Comparator<Student> {

    @Override
    public int compare(Student o1, Student o2) {
        int num = o1.getName().compareTo(o2.getName());
        if (num == 0) {
            return new Integer(o1.getAge()).compareTo(new Integer(o2.getAge()));
        }// TODO Auto-generated method stub
        return num;
    }
}

public class MapDemo5 {
    public static void main(String[] args) {
        Map<Student, String> map = new TreeMap<Student, String>(new StuNameComparator());
        map.put(new Student("zhangsan", 20), "beijing");
        map.put(new Student("lisi", 21), "tianjing");
        // map.put(new Student("lisi", 21),
        // "guangzhou");会把上面的的value替换掉(应为存入了相同的Key)
        map.put(new Student("wangwu", 22), "hunan");
        map.put(new Student("zhaoliu", 27), "hubei");
        map.put(new Student("zhaoliu", 23), "hubei");
        Set<Map.Entry<Student, String>> keyEntry = map.entrySet();
        Iterator<Map.Entry<Student, String>> me = keyEntry.iterator();
        while (me.hasNext()) {
            Map.Entry<Student, String> entry = me.next();
            System.out.println("姓名:" + entry.getKey().getName() + ",年龄：" + entry.getKey().getAge() + ",地址：" + entry.getValue());
        }

    }
}
/*
 * 以上案列用到了16-6中的学生类
 */