I have a question on how would be the best way to get the information from a string but that has JSON format.
{
"internal_id":"1234",
"moreInformation":"Failed authentication for user."
}
In this case, I want to get the value of "internal_id" and I already did, with subtring, lastIndexOf and indexOf
public static String returnInternalCode(String json){
String internalCode = json.substring(json.lastIndexOf("\"internal_id\":\"") + "\"internal_id\":\"".length(), json.length() - 1);
if (json.lastIndexOf("\"internal_id\":\"") == -1) return null;
return internalCode.substring(0, internalCode.indexOf("\""));
}
I also tried several JSONs with order changes that don't have the data and it also worked. I leave the full class of tests I did:
public class Test {
public static void main(String[] args) {
// Original JSON
String json = "{\"internal_id\":\"999999\",\"moreInformation\":\"Failed authentication for user, 1 authentication attempt remaining.\"}";
// Other JSON order
String json2 = "{\"moreInformation\":\"Failed authentication for user. Invalid response.\", \"moreInformation2\":\"Failed authentication for user. \", \"internal_id\":\"45678\"}";
// JSON without the internal_id
String json3 = "{\"moreInformation\":\"Failed authentication for user. Invalid response.\"}";
// JSON without moreInformation
String json4 = "{\"internal_id\":\"999999\"}";
System.out.println("JSON: ".concat(json4));
System.out.println("internalId: " + returnInternalId(json4));
System.out.println("moreInformation: " + returnMoreInformation(json4));
}
public static String returnInternalId(String json){
String internalCode = json.substring(json.lastIndexOf("\"internal_id\":\"") + "\"internal_id\":\"".length(), json.length());
if (json.lastIndexOf("\"internal_id\":\"") == -1) return null;
return internalCode.substring(0, internalCode.indexOf("\""));
}
public static String returnMoreInformation(String json){
String moreInformation = (json.substring(json.lastIndexOf("\"moreInformation\":\"") + "\"moreInformation\":\"".length(), json.length()));
if (json.lastIndexOf("\"moreInformation\":\"") == -1) return null;
return moreInformation.substring(0, moreInformation.indexOf("\""));
}
}
I would like to know if there are better ways to do what I did, such as with StringBuilder or StringBuffer and also to find out which way uses less memory or is faster to run, how do I know that? How long does it take to execute a method?
Thank you very much!
You can extract the values this way; Using Simple-json library
JSONObject jobj = (JSONObject) parser.parse(yourJsonString); // Pass the Json formatted String
String internal_id = (String) jobj.get("internal_id"); // Extract the value from your key
System.out.println(internal_id); // 1234
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