Question

I am trying to iterate only the first “n” values in my Map, is there any method available or i need to control it only with a count variable.

Below is an example, i have sorted a group of names belong to the same city. Now i only want the first 10 city and the person names in it.

for (Map.Entry<String, List<String>> entry : map.entrySet()) {
    List<String> list = entry.getValue();
    // Display list of people in City
}

Is there a Map implementation that can hold fixed number of key,value pairs?
Please get some directions.

Thanks,

-Vijay Selvaraj

Answer 1

How to fetch first 10 key value pairs in HashMap

HashMap is unordered. This makes the question ill-posed (unless by “first” you mean “arbitrary”).

If you want a consistent ordering of keys, you need to change the type of your map to a SortedMap, such as TreeMap.

Alternatively, if it’s the oldest elements you’re after (i.e. the ones you’ve inserted first), then LinkedHashMap is the answer.

As to actually getting the first n elements, a loop with a counter is a pretty reasonable way to do it.