public class APITester {
   public static void main(String[] args) {
      String stringJSON = "{\r\n" 
         + "\"Name\" : \"Mahesh\"," 
         + "\"RollNO\" : \"32\"\r\n" 
         + "}";  
      System.out.println(stringJSON);
       String textBlockJSON = """{"name" : "Mahesh", \"RollNO" : "32"}""";
      System.out.println(textBlockJSON);
       System.out.println("Contains: " + textBlockJSON.contains("Mahesh"));
       System.out.println("indexOf: " + textBlockJSON.indexOf("Mahesh"));
       System.out.println("Length: " + textBlockJSON.length());
   }
}

$javac APITester.java
$java APITester

{
   "Name" : "Mahesh","RollNO" : "32"
}
{
   "name" : "Mahesh",   "RollNO" : "32"
}
Contains: true
indexOf: 15
Length: 45