Question

I have a ArrayList of object as below:

Object:

String country;
String languages;
String number;

The list is as below:

India, Hindi, 500
India, English, 600
India, Bengali, 800
US, French, 700
Germany, German, 800

Above list is present in my code as:

List<MyObject> myList;  // this is the list I want to query

So there are 5 MyObject objects in the myList with values as mentioned before.

language and country properties of the object makes a unique key in my case.

So I want to fetch the corresponding number based on the language and country.

e.g. something like:

getNumber(India, Hindi) should return 500
getNumber(India, Bengali) should return 800

How to query the list in this manner ? Is it possible through Iterator ?

Thanks for reading.

Answer 1

language and country properties of the object makes a unique key in my case.

That sounds like you should quite possibly by using a map then…

How to query the list in this manner ? Is it possible through Iterator ?

Absolutely – it’ll be O(N) but it’s easy enough to do:

// TODO: Revisit the decision to make a field called "number"
// a string...
String getNumber(String language, String country) {
    for (MyObject candidate : list) {
        if (candidate.getLanguage().equals(language) &&
            candidate.getCountry().equals(country)) {
            return candidate.getNumber();
        }
    }
    // Or throw an exception, depending on what semantics are expected
    return null;
}