Removing multiple objects from a HashMap

Question

I've created a HashMap facts, which holds key(className) and value(pojo).

I want to remove more than one class objects from that hashMap while sending it to a method, the code I've below only removes one Class object (response), what if I wanted to remove more then one, (say response & HULC). Also I don't want to remove the objects from facts hashMap, hence created another copy of it.

I would appreciate your inputs thanks in advance :)

public class TempAvengersTest {

    public static void main(String[] args) {

        TempAvengersTest test = new TempAvengersTest();

        //setting avengersVo
        AvengersVo avengersVo = new AvengersVo();
        avengersVo.setNumberOfSuperHeros("6");
        avengersVo.setReleaseDate("May6,2016");

        HulcVO hulcVo = new HulcVo();
        hulcVo.setweight("2000");
        hulcVo.setAggression("Max");

        IronManVo imVo = new IronManVo();
        imVo.setAttitude("Max");
        imVo.setNewGear(true);

        HashMap<String, Integer> positiveFeedback = new HashMap<String, Integer>();
        positiveFeedback.put("IMDB", 8);
        positiveFeedback.put("rottenTomatoes", 78);

        AudienceResponseVo responseVo = new AudienceResponseVo();
        responseVo.setNegativeFeedbackInd(true);
        responseVo.setPositiveFeedback(positiveFeedback);

        HashMap<String, Object> facts = new HashMap<String, Object>();
        facts.put("Movie", avengersVo);
        facts.put("HULC", hulcVo);
        facts.put("IronMan", imVo);
        facts.put("response", responseVo);

        sendToPostScreeningHandler(test.sendToPreScreeningHandler(facts));


        System.out.println("\n\n********************************************  END  ********************************************");
    }

    private HashMap<String, Object> sendToPreScreeningHandler (HashMap<String, Object> facts){

        //" facts needs to be unchanged, Hence creating tmpFacts " !!!
        HashMap<String, Object> tmpFacts = new HashMap<String, Object>();
        tmpFacts.putAll(facts);

        //Deleting response object map from tmpFacts.
           for (Object key : facts.keySet()) {
                if("response".equals(key)){
                    tmpFacts.remove(key);
                }
           }

        System.out.println("PreScreeningEngineVo: "+AvengersJSonConverter.convertToJSON(tmpFacts));
        System.out.println("****************************************************************************************************");
        System.out.println("PostScreeningEngineVo: "+AvengersJSonConverter.convertToJSON(facts));

        return facts;
    }
}

You neither need a loop or that if for that, just call tmpFacts.remove("response") and to delete more, create a separate method with a varargs private void removeFromMap(Map<....> map, String... keysToRemove) and call it like removeFromMap("response", "blub", "test");. — Tom
– Tom, Commented Oct 26, 2015 at 1:04

Software Engineer · Accepted Answer · 2015-10-26 01:00:07Z

1

You could use a list of elements to remove and the contains method.

So this:

   if("response".equals(key))

Would change to:

if(removables.contains(key))

But, you'd have to declare removables somewhere, like this:

private List<String> removables = new ArrayList("response", "HULC");

answered Oct 26, 2015 at 1:00

Software Engineer

16.3k8 gold badges87 silver badges109 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Tom Over a year ago

So you prefer to iterate the list for each key (which is O(n)) instead if just calling tmpFacts.remove(..) for each item of that list, which would be O(1)? ... ok.

Software Engineer Over a year ago

It depends. Given the loop I assumed that you'd want to add or remove things from the removable list dynamically. If it is a static list, and my code here creates a static list, then yeah you'd remove the loop and just have the remove statements, as you said in your comment to the question.

Collectives™ on Stack Overflow

Removing multiple objects from a HashMap

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related