CODEWITHSUNDEEP
javahashmapcontains
Atwood Wang
Atwood Wang

Reputation: 201

Check whether a map contains all contents of another map

I am trying to check whether a map contains all contents of another map. For example, I have a mapA which is a Map<String, List<String>> and the elements are:

"1" -> ["a","b"]
"2" -> ["c","d"]

another mapB which is also a Map<String, List<String>>, the elements are:

"1" -> ["a"]
"2" -> ["c","d"],

I want to create a function compare(mapA, mapB) which will return false in this case.

What is the best way to do this?

Upvotes: 20

Views: 23421

Answers (4)

Aditya Aggarwal
Aditya Aggarwal

Reputation: 680

you can try this.

static boolean compare(Map<String, List<String>> mapA, Map<String, List<String>> mapB){
        return mapA.entrySet().containsAll(mapB.entrySet());
    }

As suppose, provided data is something like this:

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

            mapA.put("1", Arrays.asList("a","b"));
            mapA.put("2", Arrays.asList("c","d"));

            mapB.put("1", Arrays.asList("a"));
            mapB.put("2", Arrays.asList("c", "d"));

            System.out.println(compare(mapA, mapB));

In this case compare(mapA, mapB) method will return false. But suppose provided data is something like this:

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

            mapA.put("1", Arrays.asList("a","b"));
            mapA.put("2", Arrays.asList("c","d"));

            mapB.put("1", Arrays.asList("a", "b"));
            mapB.put("2", Arrays.asList("c", "d"));

            System.out.println(compare(mapA, mapB));

In this case, compare(mapA, mapB) method, which I have written will return true.

compare(mapA, mapB) method basically checking for all the entries in mapA with mapB, if same returning yes, else returning false;

Upvotes: 0

Tal Hakmon
Tal Hakmon

Reputation: 513

Try this code :

Assert.assertTrue(currentMap.entrySet().containsAll(expectedMap.entrySet()));

Upvotes: 1

user3699192
user3699192

Reputation: 25

The answer provided by @Jacob G wont work in your case. It will work only if there is an extra (key, value) pair in MapA. like

MapA = {"1" -> ["a","b"] "2" -> ["c","d"] }

and 

MapB = {"1" -> ["a","b"]  }.

What you need is this:

boolean isStrictlyDominate(LinkedHashMap<Integer, HashSet<Integer>> firstMap, LinkedHashMap<Integer, HashSet<Integer>> secondMap){
    for (Map.Entry<Integer, HashSet<Integer>> item : secondMap.entrySet()) {
        int secondMapKey = item.getKey();
        if(firstMap.containsKey(secondMapKey)) {
            HashSet<Integer> secondMapValue = item.getValue();
            HashSet<Integer> firstMapValue = firstMap.get(secondMapKey) ;
            if(!firstMapValue.containsAll(secondMapValue)) {
                return false;
            }

        }
    }
    return !firstMap.equals(secondMap);
}

(if you do not want to check strict domination then just return true at last return statement)

Upvotes: 0

Jacob G.
Jacob G.

Reputation: 29700

Inside your compare(mapA, mapB) method, you can simply use:

return mapA.entrySet().containsAll(mapB.entrySet());

Upvotes: 28

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