Question

I have a Array list which contains Objects of Restaurants

ArrayList<Restaurants> array_sort = new ArrayList<Restaurants>();

Restaurant object is contain its name and Id. Beside of that there is a Alphabetical Index. I need to go for the specific letter in the array when user click on the index letter. This image will give you a good idea.

Thanks in advance !

Answer 1

Using an ArrayList for this task is not a good idea because it doesn’t provide any efficient solution to your problem. I’d suggest to use a TreeMap<String,Resturant>. The good thing of the TreeMap is that it has the method

public NavigableMap<K,V> subMap(K fromKey,
                            boolean fromInclusive,
                            K toKey,
                            boolean toInclusive)

which returns a portion of the map that contains just the items you need for the specific letter, already sorted. This submap is backed by the full one so it’s a light weight object.

You can easily do something like subMap("a", true, "b", false).