Is it possible to return a HashMap object in Java?

Question

I have a method that maps keywords to a certain value. I want to return the actual hashmap so I can reference its key/value pairs

Can you add some code to your question please? Then we will have a look to see if what you want to do is correct. — mdewit
– mdewit, Commented Jun 22, 2016 at 14:50
Why would you think you can't do this? Have you tried doing it? — azurefrog
– azurefrog, Commented Jun 22, 2016 at 14:51

Community · Accepted Answer · 2017-05-23 12:07:16Z

11

Yes. It is easily possible, just like returning any other object:

public Map<String, String> mapTheThings(String keyWord, String certainValue)
{
    Map<String, String> theThings = new HashMap<>();
    //do things to get the Map built
    theThings.put(keyWord, certainValue); //or something similar
    return theThings;
}

Elsewhere,

Map<String, String> actualHashMap = mapTheThings("keyWord", "certainValue"); 
String value = actualHashMap.get("keyWord"); //The map has this entry in it that you 'put' into it inside of the other method.

Note, you should prefer to make the return type Map instead of HashMap, as I did above, because it's considered a best practice to always program to an interface rather than a concrete class. Who's to say that in the future you aren't going to want a TreeMap or something else entirely?

edited May 23, 2017 at 12:07

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answered Jun 22, 2016 at 14:51

Cache Staheli

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3 Comments

Grayson Over a year ago

Better to make return type the interface Map. This is done so that if the implementation changes from HashMap to TreeMap, for example, the calling code does not necessarily have to be changed.

Cache Staheli Over a year ago

@Grayson Good point. That's what I would have done, the OP just asked for HashMap. However, I changed it, because that is my sentiment as well.

Grayson Over a year ago

@ Cache Staheli -- if we are going to teach, we should encourage best practices. ;-)

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