How to check if Hashtable contains specific key?

Question

I have a ArrayList<String> and a Hashtable<String, Double>. So when I compare the arraylist with hash table, if the key(string) is found I want to get the value(double) and find the total value at the end when all the arraylist is compared. But it's giving score 0 always.

There is the code

ArrayList<String> Trigram = Trigrams.GenerateTrigrams(extra, 3);

// System.out.print(Trigram);
Hashtable<String, Double> map = readModleFile("Models//EnglishModel.txt");

double score = 0;

for (String temKey : Trigram) {
  if (map.contains(temKey)) {
    Double value = map.get(temKey);
    score = score + value;
  } else {
    score = 0;

  }

}
System.out.print(score);

Answer 1

There are two problems in your code:

1. Using contains instead of containsKey.
2. The else block is resetting score to 0 whenever the specified key is not found. Remove the else block.

You can also simplify your code as follows:

The following 4 lines

if (map.containsKey(temKey)) {
    Double value = map.get(temKey);
    score = score + value;
}

can be replaced with just one line

score += map.getOrDefault(temKey, 0);