com.fasterxml.jackson.databind.exc.MismatchedInputException: Can not deserialize instance of object out of START_ARRAY token - JAVA

Getting the MismatchedInputException. Searched a lot of questions here but havent found a solution yet.

Code:

import /path/to/file/Bars;
List<Bars> barResults = null;
public boolean validateData() throws IOException {
		boolean flag = false;
		try {
			if (Data.read() != -1) {
				BufferedReader reader = new BufferedReader(new InputStreamReader(Data));
				String line;
				while ((line = reader.readLine()) != null) {
					line = "[{" + line;
					System.out.println(line);
					ObjectMapper om = new ObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
					Bars ms = om.readValue(line, Bars.class);
					System.out.println(ms);
					break;
				}
				reader.close();
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		return flag;
	}

Json: //shorten for example

[{"createdOn":1601058721310,"lastUpdated":null,"lastUpdatedBy":null,"createdBy":null,"appId":null,"logical":"N","calculationDateTime":1601058721310,"mtaVersionNumber":null,"storageRegionName":"texas","createdOnDate":1601058721310,"lastUpdatedDate":0}]

Output:

[{"createdOn":1601058721310,"lastUpdated":null,"lastUpdatedBy":null,"createdBy":null,"appId":null,"logical":"N","calculationDateTime":1601058721310,"mtaVersionNumber":null,"storageRegionName":"texas","createdOnDate":1601058721310,"lastUpdatedDate":0}]
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `object` out of START_ARRAY token
 at [Source: (StringReader); line: 1, column: 1]

I am not sure what is causing this exception. When I start the application, i runs and reads the JSON fine..but throws exception.

In your call to readValue you are passing Bars.class as the second argument, which tells Jackson that the first argument (line) is a JSON representation of a Bars instance and that's what it should return.

JSON objects start with a {, and because you've asked Jackson to deserialize an object, it expects the input to start with a {. But the JSON that you're passing in, line, isn't a Bars instance: it's an array containing a Bars instance, and it starts with a [.

So it throws an error message that says "I was told an object would be here, but instead I found the start of an array".

To fix it, you can either ask Jackson to deserialize an array of "Bar" objects by changing the second argument of readValue to Bars[].class and then extract the bar instance from the array, or you could stop adding a "[" to the start of the line and chop the "]" off the end of it so that it's just a single object and not an array containing that single object.