Tuesday, September 20, 2022

[FIXED] How to convert List to Map?

Issue

Recently I have conversation with a colleague about what would be the optimal way to convert List to Map in Java and if there any specific benefits of doing so.

I want to know optimal conversion approach and would really appreciate if any one can guide me.

Is this good approach:

List<Object[]> results;
Map<Integer, String> resultsMap = new HashMap<Integer, String>();
for (Object[] o : results) {
    resultsMap.put((Integer) o[0], (String) o[1]);
}

Solution

List<Item> list;
Map<Key,Item> map = new HashMap<Key,Item>();
for (Item i : list) map.put(i.getKey(),i);

Assuming of course that each Item has a getKey() method that returns a key of the proper type.



Answered By - Jim Garrison
Answer Checked By - Terry (PHPFixing Volunteer)

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