can i use from jdk, Map 1key to multi value?

Question

i want use map have multi value

ex)

HashMap<String, ArrayList<String>> 

but it seems too bad

may be jdk have map, this role?

thank so read this question

Answer 1

It is perfectly valid to define the mutimap the way you have done. JDK does not prvoide a collection called multimap. Althtough apache commons has defined a MultiMap interface with implentation classes such as MultiHashMap and MultiValueMap .

If you don't want to use apache commons MultiMap then here is the tutorial to help you learn how you can create your own multimap using java HashMap:

http://docs.oracle.com/javase/tutorial/collections/interfaces/map.html

Answer 2

Try Map

Map<String, ArrayList<String>> sampleMap = new HashMap<String, ArrayList<String>>();

        ArrayList<String> sampleList = new ArrayList<String>();
        sampleList.add("Value1");
        sampleList.add("Value2");
        sampleList.add("Value3");

        sampleMap.put("Key1", sampleList);
        sampleMap.put("Key2", sampleList);
        sampleMap.put("Key3", sampleList);

        System.out.println("SampleMap : "+sampleMap);