Map的应用

1.纸张尺寸

map嵌套map

entryset的使用——循环输出map

import java.util.*;

//import com.sun.javafx.collections.MappingChange.Map;

public class Main{
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		//用于存储A0-A9，以及对应的大小map集合
		HashMap<String,Map<Integer, Integer>> map = new HashMap<>();
		int l = 1189;
		int w = 841;
		for(int i=0;i<=9;i++) {
			String s = "A"+i;
			
			HashMap<Integer,Integer> hashMap = new HashMap<>();
			hashMap.put(l, w);
			map.put(s, hashMap);
//			System.out.print(s+" ");
			int t = l/2;
			l = w;
			w = t;
		}
		
		String x = scan.next();
		Map<Integer,Integer> values = map.get(x);
		for(Map.Entry<Integer, Integer> entry : values.entrySet()) {
			System.out.println(entry.getKey());
			System.out.println(entry.getValue());
		}
	}
}