JsonParseException is subclass of JsonProcessingException. This exception occurred because parsing issues or non-well-formed content because of not fulling JSON syntax specification.

JsonParserException Example

Here JSonParserException occurred because not fulfilling the syntax specification because two curly brackets ({) used continuously

public class StudentDetail {
	private int rollNumber;
	private String firstName;
	private String lastName;

	//getter and setter of class
}

public static void main(String[] args) {

	    String json="{{\"rollNumber\":21 , \"firstName\":\"Saurabh\" , \"lastName\":\"Gupta\"}} ";

	    System.out.println(json);
		try
		{
	    ObjectMapper mapper = new ObjectMapper();
	    StudentDetail student= mapper.readValue(json, StudentDetail.class);
	    System.out.println(student);
		}
		catch(IOException ex)
		{
			ex.printStackTrace();
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}

JsonParserException Stacktrace

 {{"rollNumber":21 , "firstName":"Saurabh" , "lastName":"Gupta"}} 
com.fasterxml.jackson.core.JsonParseException: Unexpected character ('{' (code 123)): was expecting double-quote to start field name
 at [Source: (String)" {{"rollNumber":21 , "firstName":"Saurabh" , "lastName":"Gupta"}} "; line: 1, column: 4]
    at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1804)
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:693)
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportUnexpectedChar(ParserMinimalBase.java:591)
    at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._handleOddName(ReaderBasedJsonParser.java:1767)
    at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.nextToken(ReaderBasedJsonParser.java:692)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:155)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3004)
    at com.fiot.json.jackson.exceptions.TestJacksonExample2.main(TestJacksonExample2.java:23)

Solutions

To fix this issue remove one level of the curly bracket from start and end so that fulfill JSON specification. The correct JSON for this example would be :

 String json="{\"rollNumber\":21 , \"firstName\":\"Saurabh\" , \"lastName\":\"Gupta\"}";

As per JSON specification after curly bracket ({) only allow double quote for showing properties name or square bracket ([) if need to show set of objects or values.

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References

https://fasterxml.github.io/jackson-core/javadoc/2.2.0/com/fasterxml/jackson/core/JsonParseException.html