Best design/coding to accomplish the below requirement?

Question

I am using Java 1.7. I have below map.

Map<String, String> keyValues = new HashMap<>();

But map can contain values as below.

keyValues.put("one", "value1");
keyValues.put("two", "value2");

OR

keyValues.put("four", "value1");
keyValues.put("two", "value2");
keyValues.put("seven", "value3");

OR

keyValues.put("one", "value1");
keyValues.put("two", "value2");
keyValues.put("three", "value3");

Basically the map can contain N values where is N is generic it can contain any number of values.

I have one more value for group of keys as below.

keys one, two belongs to 12345SRT
keys one, two, three, four belongs to 12345SRTSSS
keys four, two, seven belongs to 764RTYL87

Now map can contain any one of above key sets.

In that case based on the key set in the map it has to return corresponding value.

Ex:

If map contains one and two then it should return 12345SRT.
     If map contains four,two and seven then logic should return 764RTYL87.

What is the best place to keep above key sets and corresponding values? Shall i consider enum? The logic has to take map and return value.

What is the best way to do that?

Maybe it just me but your example makes me think about binary representation :) — BobTheBuilder, Jan 02 '14 at 07:49
Not sure I got your requirements correctly but it seems you just have to exchange key and value in your map. — Henry, Jan 02 '14 at 08:12

score 1 · Accepted Answer · edited May 23 '17 at 12:11

1

You can use Apache MultiKeyMap

Example

 MultiKeyMap multiKeyMap = new MultiKeyMap();
 multiKeyMap.put("New York","IBM","Sam");
 multiKeyMap.put("Sydney","Infosys","Honey");
 multiKeyMap.put("Prague","JP Morgan","Peter");
 multiKeyMap.put("Scotland","RBS","Deny");
 multiKeyMap.put("Paris","Nomura","Lily");
 multiKeyMap.put("Melbourne","Citi Bank","Sandy");
 multiKeyMap.put("Aukland","Bank of America","Tommy");

Resultant map

enter image description here

Similar question: How to implement a Map with multiple keys?

EDIT :

You can have a custom key class which can have N number of keys. Something like

Class MyKey{
  List<String> keys;
}

Map<MyKey, String> keyValues = new HashMap<>();

Also override appropriate methods of Map like equals,hashcode,get etc.

edited May 23 '17 at 12:11

Community

1
1

answered Jan 02 '14 at 07:43

Ajinkya

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1

That doesn't help OP at all. Can you provide some code with it. – Narendra Pathai Jan 02 '14 at 07:43
Karna, thanks for ur answer.But i here i have not two keys. it can contain one or two or three keys. Still can i use multikeymap? – user755806 Jan 02 '14 at 07:55

venkat530 · Answer 2 · 2014-01-02T08:17:49.327

0

You can use as below :

Map<String, ArrayList<String>> keyValues = new HashMap<String, ArrayList<String>();
keyValues.put("12345SRT",["one","two"]);
keyValues.put("12345SRTSSS",["one", "two", "three", "four"]);
keyValues.put("764RTYL87",["four", "two", "seven"]);

Ex:if you have a map object with keys as "one" and "two"

String getKey(map){
    for (Map.Entry<String, Object> e : keyValues.entrySet()) {
        String key = e.getKey();
        ArrayList<string> value = e.getValue();
        if(value.containsAll(map.keySet())){
            return key;
        }
    }
}

edited Jan 02 '14 at 08:17

answered Jan 02 '14 at 08:00

venkat530

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2
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venkat, but using this approach i cannot get key based on values right? – user755806 Jan 02 '14 at 08:01

score 0 · Answer 3 · answered Jan 02 '14 at 08:12

Maybe this?

HashMap<Set<String>, String> multiMap = new HashMap<Set<String>, String>();
Set<String> mk1 = new HashSet<String>();
mk1.add("one");
mk1.add("two");
mk1.add("three");
multiMap.put(mk1, "derp");

Set<String> checker = new HashSet<String>();
checker.add("two");
checker.add("three");
checker.add("one");

if(multiMap.containsKey(checker))
    System.out.println(multiMap.get(checker));

Try running this and see if it's the behavior you're wanting.

Best design/coding to accomplish the below requirement?

3 Answers3