How to compare two JSON Strings for equality using GSON?

Question

I am trying to compare two JSON Strings for equality. I found this solution which uses Jackson as shown below but in all my project I am using GSON so I need to do the same thing using GSON.

ObjectMapper mapper = new ObjectMapper();
JsonNode tree1 = mapper.readTree(jsonString1);
JsonNode tree2 = mapper.readTree(jsonString2);
if (tree1.equals(tree2)) { 
  // yes, contents are equal -- note, ordering of arrays matters, objects not
} else { 
  // not equal
}

Is there any way to compare two JSON String for equality using GSON?

In theory you just deserialize into Maps/Lists and compare the two roots. — Hot Licks, Sep 04 '14 at 00:06

score 10 · Answer 1 · edited May 23 '17 at 10:31

10

According to this answer you could use this:

JsonParser parser = new JsonParser();
JsonElement o1 = parser.parse("{a : {a : 2}, b : 2}");
JsonElement o2 = parser.parse("{b : 2, a : {a : 2}}");
assertEquals(o1, o2);

Unfortunately I'm guessing this isn't quite as clean as you were hoping, but it should work.

In any case it might be helpful to look through the other answers in that thread (although not all use GSON), so if this doesn't work out, perhaps one of those might.

edited May 23 '17 at 10:31

Community

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answered Sep 04 '14 at 00:08

Akshay

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Hi - tried this with the latest GSON 2.4 and this didn't work. Confirmed this returns false: new JsonParser().parse("{a : {a : 2}, b : 2}").equals(new JsonParser().parse("{b : 2, a : {a : 2}}")) – Will Glass Nov 19 '15 at 02:29

score 0 · Answer 2 · answered Apr 26 '20 at 14:54

I don't believe that Gson library makes any statements that the JSON output from two equal JSON elements will be the same, mostly due to the order of properties in objects, since the standard doesn't require any kind of order. Gson library itself doesn't offer a functionality to compare JSON elements or serialized representation thereof. One can write a function that will compare two JSON elements and properly descend into the underlying compound structures (i.e. arrays and objects).

I was able to find this article here that seems to contain a working comparison function.

How to compare two JSON Strings for equality using GSON?

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