【转】HashMap嵌套遍历

网上有好多关于HashMap嵌套遍历的讨论，但有些言之不祥，特此以如下示例进行演示。

import java.util.*;
public class mutil_hashmap {

    public static void main(String args[]) {

        Map<String, Map<String, int[]>> mutil_hashmap = new HashMap<String, Map<String, int[]>>();       
        Map<String, int[]> inserted_hashmap = new HashMap<String, int[]>();
        int nextInf[] = new int[8];

        for (int i = 0; i < 8; i++) {
            nextInf[i] = i * 10;
        }

        inserted_hashmap.put("0.0.0.100", nextInf);
        mutil_hashmap.put("R0", inserted_hashmap);



        //一般遍历方法
        Iterator out_iterator = mutil_hashmap.keySet().iterator();       
        while (out_iterator.hasNext()) {

            String router=(String)out_iterator.next();
           
            System.out.print(router);
           
            HashMap in_hashmap=(HashMap)mutil_hashmap.get(router);
           
            Iterator in_iterator = in_hashmap.keySet().iterator();
           
            while (in_iterator.hasNext()) {
               
                String dest=(String)in_iterator.next();
               
                System.out.println("->"+dest+":");
               
                               
                for(int nexthop_interface : (int[])in_hashmap.get(dest)){
                   
                    System.out.print(nexthop_interface+" ");
                }
                   
            }
           
            System.out.println();
           
        }      

        //利用Map.Entry进行遍历
        Iterator<Map.Entry<String, Map<String, int[]>>> it = mutil_hashmap
                .entrySet().iterator();
       
        while (it.hasNext()) {
           
            // entry.getKey() 返回与此项对应的键
            // entry.getValue() 返回与此项对应的值
           
            Map.Entry entry = (Map.Entry)it.next();
            System.out.print("\n"+entry.getKey());   
           
            HashMap tmp_in_hashmap=(HashMap)entry.getValue();
           
            Iterator<Map.Entry<String, int[]>> in_iterator = tmp_in_hashmap
            .entrySet().iterator();
           
            while(in_iterator.hasNext()){
                Map.Entry in_entry = (Map.Entry)in_iterator.next();
                System.out.println("->"+in_entry.getKey()+":");
                int[] array=(int[])in_entry.getValue();
                for(int each:array){
                    System.out.print(each+" ");
                }
            }          
           
        }       
    }
}