Given a key, how to display the ArrayList stored as the value?

Question

i have a hashmap where every key has many values(stored in a arraylist). How to display the arraylist i.e the values for a particular key in a hashmap in java??

Your question is pretty unclear. What are you trying to achieve? What have you tried so far? — Jason Hall
– Jason Hall, Commented Apr 13, 2010 at 18:15
Your question is a little vague. Do you want to use an ArrayList as a key in a Java HashMap? Maybe a few more sentences to clarify your question would be good. — Rob Heiser
– Rob Heiser, Commented Apr 13, 2010 at 18:16

OscarRyz · Accepted Answer · 2010-04-13 18:32:06Z

6

import java.util.*;

public class PrintListFromHashMap {

    public static void main( String [] args ) {

        Map<String,List<String>> hashMap = new HashMap<String,List<String>>();

        hashMap.put( "list",       new ArrayList<String>(Arrays.asList("A","B","C")));

        System.out.println( hashMap.get("list") );

    }

}

$ javac PrintListFromHashMap.java 
$ java PrintListFromHashMap
[A, B, C]

edited Apr 13, 2010 at 18:32

answered Apr 13, 2010 at 18:20

OscarRyz

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2 Comments

matt b Over a year ago

you know you could just do hashMap.put( "list", Arrays.asList("A","B","C"));

OscarRyz Over a year ago

@matt b Yeah, but that wouldn't be an ArrayList ( as the OP needed )

BalusC · Accepted Answer · 2010-04-13 18:20:33Z

1

So, you want to be able to associate multiple values with one key? If so, then just use either a Map<K, Collection<V>>, or Google Collections MultiMap<K, V>

answered Apr 13, 2010 at 18:20

BalusC

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