CODEWITHSUNDEEP
javajson
Rahul Ramamoorthy
Rahul Ramamoorthy

Reputation: 31

Java: Merging two JSON objects without iterating

I have two JSON objects like 

{  
   "key1":"value1",
   "key2":"value2",
   "key3":"value3",
   "key4":"value4"
}

and 

{
   "key2":"value1",
   "key4":"value2",
   "key6":"value3",
   "key8":"value4"
}

I want to merge these two JSON objects into single Json object without iterating through each key and the final result should be 

{
   "key1":"value1",
   "key2":"value1",
   "key3":"value3",
   "key4":"value2",
   "key6":"value3",
   "key8":"value4"
}

Upvotes: 0

Views: 138

Answers (2)

Oswaldo Junior
Oswaldo Junior

Reputation: 136

Consider using a library that does this job for you, like JSON Merge, available at Maven Central.

You will get the desired result with a single line of code:

JSONObject result = new JsonMerger<>(JSONObject.class).merge(json2, json1);

Note: the first JSON parameter passed to the merge method will always have more precedence/importance than the second one in case of key collisions.

This library works with Jackson, Gson, and other JSON providers as well.

Upvotes: 0

Amit Phaltankar
Amit Phaltankar

Reputation: 3424

Use any Json Mapper (e.g Jackson) convert json to Map.

ObjectMapper mapper = new ObjectMapper();
Map<String, Object> map = mapper.readValue(json, new TypeReference<Map<String, String>>(){})

once you get two maps like this you can merge them 

Map<String, Object> mergedMap = new HashMap<>();
mergedMap.putAll(map1);
mergedMap.putAll(map2);
String json = mapper.writeValueAsString(mergedMap);

Upvotes: 2

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