Question

I have an ArrayList of objects where each object contains a string ‘word’ and a date. I need to check to see if the date has passed for a list of 500 words. The ArrayList could contain up to a million words and dates. The dates I store as integers, so the problem I have is attempting to find the word I am looking for in the ArrayList.

Is there a way to make this faster? In python I have a dict and mWords[‘foo’] is a simple lookup without looping through the whole 1 million items in the mWords array. Is there something like this in java?

    for (int i = 0;  i < mWords.size();  i++) {
        if ( word == mWords.get(i).word ) {
           return mWords.get(i);
        }
    }  

Answer 1

If the words are unique then use HashMap. I mean, {“a”, 1}, {“b”, 2}

Map<String, Integer> wordsAndDates = new HashMap<String, Integer>();
wordsAndDates.put("a", 1);
wordsAndDates.put("b", 2);

and wordsAndDates.get("a") return 1

If not you shouldn’t use HashMap because it overrides previous value. I mean

wordsAndDates.put("a", 1);
wordsAndDates.put("b", 2);
wordsAndDates.put("a", 3);

and wordsAndDates.get("a") return 3

In such case you can use ArrayList and search in it