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
*/