HashMap嵌套HashMap集合

package com.cnd05;
 
import java.util.HashMap;
import java.util.Set;
 
//HashMap嵌套HashMap结构
public class TreeMapDemo2 {
 
	public static void main(String[] args) {
		
		//创建集合
		HashMap<String,HashMap<String,Integer>> sumMap=new HashMap<String,HashMap<String,Integer>>();
		
		//先存储元素，后遍历元素
		HashMap<String,Integer> hm1=new HashMap<String,Integer>();
		hm1.put("高跃", 22);
		hm1.put("李杰", 20);
		HashMap<String,Integer> hm2=new HashMap<String,Integer>();
		hm2.put("方乐", 24);
		hm2.put("贾芳", 23);
		//存储元素
		sumMap.put("一年级", hm1);
		sumMap.put("二年级", hm2);
		
		
		//遍历元素
		Set<String> sumMapSet=sumMap.keySet();
		for(String key:sumMapSet) {
			System.out.println(key);
			HashMap<String,Integer> subMapValue=sumMap.get(key);
			//遍历键值(HashMap结构)
			Set<String> subMapValueSet = subMapValue.keySet();
			for(String key2:subMapValueSet) {
				Integer subMapValueSetValue=subMapValue.get(key2);
				System.out.println("\t"+key2+"---"+subMapValueSetValue);
			}
		}
		
		
 
	}
 
}

运行结果为：

一年级
    高跃---22
    李杰---20
二年级
    贾芳---23
    方乐---24