Using JDK 15

Text Blocks : Text blocks start with a “”” (three double-quote marks) followed by optional whitespaces and a newline.

Please find the solution below to convert json to string and vice-versa, it might help you in some way.

public class Test {
  public static void main(String[] args) throws JsonProcessingException {
    String s = """
        {
        "students":[{
        "name": "Albert",
        "code":"GE",
        "marks":[{"mark":"20"},{"mark":"40"}]},
        {
        "name": "Gert",
        "code":"LE",
        "marks":[{"mark":"26"}]},
        {
        "name": "John"
        },
        {
        "name": "John Doe",
        "code":"LP",
        "marks":[{"mark":"40"}]}
        ]
        }
        """;
    //JSON TO STRING
    ObjectMapper mapper = new ObjectMapper();
    String s2 = mapper.writeValueAsString(s);
    System.out.println("JSON TO STRING:" + s2);

    //STRING TO JSON
    String s3 = mapper.readValue(s2, new TypeReference<>() {});
    System.out.println("STRING TO JSON:" + s3);

  }
}

Output:

 JSON TO STRING:"{\n\"students\":[{\n\"name\": \"Albert\",\n\"code\":\"GE\",\n\"marks\":[{\"mark\":\"20\"},{\"mark\":\"40\"}]},\n{\n\"name\": \"Gert\",\n\"code\":\"LE\",\n\"marks\":[{\"mark\":\"26\"}]},\n{\n\"name\": \"John\"\n},\n{\n\"name\": \"John Doe\",\n\"code\":\"LP\",\n\"marks\":[{\"mark\":\"40\"}]}\n]\n}\n"
    STRING TO JSON:{
    "students":[{
    "name": "Albert",
    "code":"GE",
    "marks":[{"mark":"20"},{"mark":"40"}]},
    {
    "name": "Gert",
    "code":"LE",
    "marks":[{"mark":"26"}]},
    {
    "name": "John"
    },
    {
    "name": "John Doe",
    "code":"LP",
    "marks":[{"mark":"40"}]}
    ]
    }