Parse Json from Java properties file using gson library

Question

I need to read and parse a json array from java properties file. I'm able to read the properties file and get the json array String. But I'm unable to parse the json array and get the values. I'm using gson library. Here is the data from properties file

jsonarray = [ { key1 : value1, key2 : value2 } ]

Code:

Properties properties = new Properties();
properties.load(new FileInputStream(filePath));
String jsonArray = properties.getProperty("jsonarray")
JsonElement element = new JsonPrimitive(jsonArray);
JsonArray array = element.getAsJsonArray();

I'm getting IllegalStateException

java.lang.IllegalStateException: Not a JSON Array: "[ { key1 : value1, key2 : value2 } ]"

The problem is it is taking extra double quotes at the beginning and at the end.

I have tried adding quotes to keys and values, but with no success. I need to use gson library itself, so please don't suggest other libraries. I cannot create a POJO class for it and use new Gson().fromJson(jsonArray), so kindly please don't suggest that also.

I've searched and tried a lot without success. The method I referred is given here

Thanks in advance

Edit 1: I've tried the following in properties file

jsonarray = [ { "key1" : "value1", "key2" : "value2" } ]

and I got same exception like

java.lang.IllegalStateException: Not a JSON Array: "[ { \"key1\" : \"value1\", \"key2\" : \"value2\" } ]"

I tried to create a JsonArray object in code and print it

JsonArray array = new JsonArray();
JsonObject object = new JsonObject();
object.addProperty("key1", "value1");
object.addProperty("key2", "value2");
array.add(object);
System.out.println(array.toString());

The output was as below

[{"key1":"value1","key2":"value2"}]

this is not a valid json format . it should be like [{"key1": "valu1","key2":"value2"}] — cool
– cool, Commented Mar 22, 2018 at 14:40
Yes, I've tried that also. Does space matter? I had put spaces before and after colon — Nagabhushan S N
– Nagabhushan S N, Commented Mar 22, 2018 at 14:43
No space will not make any difference but quotation marks will — cool
– cool, Commented Mar 22, 2018 at 14:46
you should send an input like this [{\"key1\":\"value1\",\"key2\":\"value2\"]} as java string — cool
– cool, Commented Mar 22, 2018 at 14:48
Your data should be like { "key1" : "value1", "key2" : "value2" } Check here jsoneditoronline.org/?id=d8410952f64e88bd8296f0808c25ed50 — Alpesh Jikadra
– Alpesh Jikadra, Commented Mar 22, 2018 at 14:49

Sotirios Delimanolis · Accepted Answer · 2018-03-22 15:01:26Z

1

The Javadoc of JsonPrimitive you've used here

JsonElement element = new JsonPrimitive(jsonArray);

states

Create a primitive containing a String value.

When you then do

JsonArray array = element.getAsJsonArray();

it'll obviously fail because element is a JSON String, not a JSON array. Just parse the JSON directly

JsonArray array = new Gson().fromJson(jsonArray, JsonArray.class)

This is all after you've changed your properties file content to be actual JSON

jsonarray = [ { "key1" : "value1", "key2" : "value2" } ]

answered Mar 22, 2018 at 15:01

Sotirios Delimanolis

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