如何检查hashmap中的值

Question

I wanted to make a method to check if I can see if each of my piles have 6 cards in it. This is my method

public boolean checkIfPileHasSixCards() {

        map.put("tpile1", tpile1);
        map.put("tpile2", tpile2);
        map.put("tpile3", tpile2);
        for (ArrayList<Card> value : map.values()) {
              int size=value.size();
              if(size==6) {
                  return true;
              }
        }
        return false;

    }

Is my logic correct, is there a more efficient way I can iterate over the values and check if each value (ArrayList) size is 6?

Answer 1

Returning true inside the loop is not correct - this way, your method will return true if any list in the map has six elements, not if all of them do. Instead, you should return false if a list doesn't have six elements, and only return true after you're done iterating the values:

for (List<Card> value : map.values()) {
      int size = value.size();
      if(size != 6) {
          return false;
      }
}
return true;

Note, by the way, that using Java 8's stream could make this snippet a lot cleaner. It won't be more efficient (it's still an O(n) operation in the worst case), but it will definitely be more concise:

return map.values().stream().allMatch(l -> l.size() == 6);