Updating JSON Key within Json File

Question

I have the following code to update the key "runTimeDate" within my json file.

`final LocalDate plus180Days = LocalDate.now().plusDays(180);
 DateTimeFormatter dateTimeFormatter = 
     DateTimeFormatter.ofPattern("yyyy-MM-dd");
 String substituteDate = plus180Days.format(dateTimeFormatter);
 String jsonFile = "src/examples/sample.json";

 public String Body_ValueDate()
 {
  return jsonFile.replaceAll("\"runTimeDate\"", "\"" + substituteDate + 
               "\"");
 }
 public String Body_KeyDate()
 {
  return Body_ValueDate().replaceAll("\"keyDate\"", "\"" + 
      substituteDate + "\"");
 }`

I used the code above from here: https://stackoverflow.com/questions/7463414/what-s-the-best-way-to-load-a-jsonobject-from-a-json-text-file#:~:text=23-,With%20java%208,-you%20can%20try

Thing is, the date is not getting updated. plus180Days is basically a function adding 180 days from current date. Can anyone share what I am missing here?

final LocalDate plus180Days = LocalDate.now().plusDays(180);

Sample Json

{
  "city": {
  "details": {
  "a1": "AUS",
  "a2": "AUS",
  "country": "AUS"
  }
},
 "detail": {
    "getCountryDetail": {
        "b1": "SYD",
        "b2": "MEL",
        "country": {
            "keyDate|AUS|1234|SYD|MEL": {
                "date1": "runTimeDate",
                "time1": "15:38",
                "date2": "runTimeDate",
                "time2": "19:13"
                 },
            "keyDate|AUS|1234|ADL|MEL": {
                "date1": "runTimeDate",
                "time1": "15:38",
                "date2": "runTimeDate",
                "time2": "19:13"
                 }
               }
             }
           }
         }

I am using the updated json method "Body_KeyDate" as body parameter for my rest assured method as per here:

@Test
public void UA_Avail_Cascading_Request()
  throws IOException
{
 Response response = RestAssured.given()
    .header(readConfigFile())
    .contentType("application/json")
    .body(Body_KeyDate())
    .when()
    .post(readBaseUrl() + "samplePage")
    .then().statusCode(200)
    .log().all()
    .extract().response();
   }

Following solution worked: with ObjectMapper

public JsonNode RequestBody_DynamicDate() throws Exception
  {
  String requestBodyJson = loadJson("Sample.json");
  String removeKeyDate = requestBodyJson.replace("keyDate", NEW_DATE);
  String removeValueDate = removeKeyDate.replace("runTimeDate", NEW_DATE);
  JsonNode processedNewDates = OBJECT_MAPPER.readTree(removeValueDate);
  System.out.println("New JSON Body: "
    + OBJECT_MAPPER
    .writerWithDefaultPrettyPrinter()
    .writeValueAsString(processedNewDates));
  return processedNewDates;
}

Here is the code for loadJson: BASEPATH is the folder location

String loadJson(String filePath)
  {
    try
    {
      return new String(Files.readAllBytes(Paths.get(BASEPATH + filePath)));
    }
    catch (Exception e)
    {
      Assertions.fail("unable to load test data, check file path, and format");
      throw new RuntimeException();
    }

Hope this helps someone. Also turns there was some restrictions and limitations on which library and packages can be used.