19-Map集合-12-常用对象API(集合框架-Map集合练习-Map查表法)

package cn.itcast.map.demo;

import java.util.HashMap;
import java.util.Map;

public class MapDemo {

public static void main(String[] args) {

/*
* Map在有映射关系时，可以优先考虑
*
* 在查表法中的应用较为多见。
*/
String week=getWeek(1);
System.out.println(week);
System.out.println(getWeekByMap(week));
}
//这种方法必须要求映射的一方是有序的
public static String getWeek(int week) {

if(week<1	||	week>7)
throw new RuntimeException("wrong number!");

String[] weeks={"","星期一","星期二","星期三","星期四","星期五","星期六","星期日"};
return weeks[week];
}

//而Map集合不需要有序

public static String getWeekByMap(String week){

Map<String,String> map = new HashMap<String,String>();
map.put("星期一", "Mon");
map.put("星期二", "Tus");
map.put("星期三", "Wes");

return map.get(week);
}

}