Fastest way to find certain value of variable of object in object array

Question

I have an ArrayList of custom objects I called Questions. These Questions contain the question, a unique ID, and an ArrayList of Answers. Now I'm trying to search for the question with a specific unique ID. This is what I'm currently doing but I'm worried this might take too long for a big list, so I was wondering if there was a faster way to do this.

public Question getQuestion(String idLookingFor) {
    for (Question question : questions) {
        if (question.getId().equals(idLookingFor))
            return question;
    }
    return null;
}

YoungHobbit · Accepted Answer · 2015-09-12 18:13:15Z

5

You can use HashMap for storing the information about ID as key and Question as value. I am assuming, ID is stored as Interger.

Map<Integer, Question> map = new HashMap<>();

The Map will provide you O(1) time complexity for searching the question.

edited Sep 12, 2015 at 18:13

answered Sep 12, 2015 at 18:09

YoungHobbit

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2 Comments

silverAndroid Over a year ago

Thanks! I can't believe I forgot about Map!

Jacek Cz Over a year ago

Yes, storing in both containers, surprising (List and Map) at first look, but give fast information: order what item was added (list) and fast search by key via Map. Use such pattern once in a month, id works goog.

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