获取HashMap的所有子级 <Integer, ArrayList<String> &gt;

Question

I use this code for add to hashmap :

static HashMap<Integer, ArrayList<String>> arrayMap = new HashMap<Integer, ArrayList<String>>();

ArrayList<String> list = new ArrayList<String>();
list.add("t");
list.add("b");
arrayMap.put(12, list);

ArrayList<String> list = new ArrayList<String>();
list.add("y");
list.add("x");
arrayMap.put(18, list);

this code work correct

but i cant get child of arrayMap in foreach

for(arrayMap .... ){
     return // 12:t,b   18:y,x
}

My try :

for (int a = 0; a < arrayMap.size(); a++)
        {
            HashMap<String, Integer> tmpData = (HashMap<String, Integer>) arrayMap.get(a);
            Set<String> key = tmpData.keySet();
            Iterator it = key.iterator();
            while (it.hasNext()) {
                String hmKey = (String) it.next();
                Integer hmData = (Integer) tmpData.get(hmKey);

                System.out.println("Key: " + hmKey + " & Data: " + hmData);
                it.remove(); // avoids a ConcurrentModificationException
            }

        }

Answer 1

You need to iterate over the entrySet()

https://developer.android.com/reference/java/util/Map.html#entrySet()

Answer 2

You'll want to iterate over the each entry in the HashMap in a nested loop like this:

for(Map.Entry<Integer, ArrayList<String>> entry : arrayMap.entrySet()){
   //entry.getKey() will be each key in the HashMap
    for(String str : entry.getValue()){
         // str is one entry of the ArrayList for that Key
    }
}