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I need advice into how to work out a method in Android which has to pick a string loaded with JSON data and then convert it back to JSON.
For the time being, I have programmed the following but I'm not sure if I'm on the right track or not.
private void convert_JSON()
{
String json;
//funcions per a cridar el string amb JSON i convertir-lo de nou a JSON
JSONArray jsas = new JSONArray();
for (int i =0; i < jsas.length(); i++)
{
JSONObject message = jsas.getJSONObject(i);
String content = message.getString("content");
}
}
The JSON is loaded into a String in this other method:
private void read_JSON(String json)
{
JSONObject jObject = new JSONObject(json);
JSONArray jso3 = new JSONArray (jObject.getString("Nombres_Hijos"));
String name = jso3.getString("Nombre");
System.out.println(name);
String surname = jso3.getString("Apellidos");
System.out.println(surname);
int date = jso3.getInt("Año_nacimiento");
System.out.println(date);
JSONArray jsa2 = jso3.getJSONArray ("Nombres_Hijos");
String names = jsa2.toString();
for (int i=0; i < jsa2.length(); i++)
{
System.out.println(jsa2.getString(i));
}
jso3.toString(json);
}
And, lastly, the JSON is created within the MainActivity.java, not as a split file yet that does work correctly:
private void create_JSON(String json)
{
JSONObject jso = new JSONObject();
try {
jso.put("Nombre","Miguel");
jso.put("Apellidos", "Garcia");
jso.put("Año_nacimiento", 1990);
JSONArray jsa = new JSONArray();
jsa.put("Blur");
jsa.put("Clur");
jso.put("Nombres_Hijos", jsa);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return jso.toString();
In short: what I want to know is if my method convert_JSON is on the right track or I'm misunderstanding how it's supposed to work like.
Thank you very much for your help.
Yours sincerely,
Mauro.
You can convert a jsonstring back to json using the following JSONObject(String json) constructor:
JSONObject jsonObject = new JSONObject(jsonString);
Just, put it inside a try catch block and you should be good to go :)
You can create a JSONObject from a String using the constructor:
JSONObject json = new JSONObject(myString);
And to convert your JSONObject to a String, just use the toString() method:
String myString = json.toString();
Additionally, if you are trying to get a specific String value from the JSONObject, you can do this:
if (json.has("content"))
{
String content = json.getString("content");
//do something with content string
}
Finally, if you aren't very comfortable using JSONObject, I recommend using the tools provided by droidQuery to help you parse, such as:
Object[] array = $.toArray(myJSONArray);
and
Map<String, ?> map = $.map(myJSONObject);
If you want a pure copy/paste example have a look here
Alternatively I would suggest using one of the many well documented libraries. My personal favourite is GSON
Plenty of examples on the net on how to use this.
Related
I'm learning how to work with JSON's in java and I'm having a problem using getString for one of my keys. My code is here:
public static void getJSON(String matchID){
String s = "";
String test = "{\"employees\":[{\"firstName\":\"John\", \"lastName\":\"Doe\"}]}";
try {
JSONObject hi = new JSONObject(test);
JSONArray stuff = hi.getJSONArray("employees");
String[] items = new String[stuff.length()];
items[0] = stuff.getString("firstName");
} catch (JSONException e) {
e.printStackTrace();
}
}
The "getString" is underlined in red, and the "The method getString(int) in the type JSONArray is not applicable for the arguments (String)" I was following an answer to another question word for word almost, and this happens, any advice? Thanks!
EDIT:
I need to get the specifics by name ie. "firstName" because I will be working with thousands of JSONs that each have hundreds of lines.
You need to get the JSOnObject first from the JSONArray(stuff) before you can call getString().
if you want to get the first element in the jsonarray and get its string this is how you would do it
JsonObject obj = stuff.getJsonObject(0);
String name = obj.getString("firstname");
So I figured out my problem, I didn't realize I had an JSONObject first, my apologies. Fixed like this:
JSONObject hi = new JSONObject(test);
JSONArray stuff = hi.getJSONArray("employees");
JSONObject name = stuff.getJSONObject(0);
String[] items = new String[hi.length()];
items[0]=name.getString("firstName");
System.out.println(items[0]);
you can try the simplest way to Parse in JSON
JSONParser parser=new JSONParser();
String s = "{\"employees\":[{\"firstName\":\"John\", \"lastName\":\"Doe\"}]}";
try{
Object obj = parser.parse(s);
JSONArray array = (JSONArray)obj;
System.out.println(array.get(1));
}catch(ParseException pe){
}
I have created a java server which gets HTTP GET request url as
/Star/getDetails?sentMsg=data.requestorName:ABC,data.companyName:EFG,portfolios:
[{name:,placeholder:Portfolio 1,positions:[{ticker:T1234,weight:29.85},
{ticker:T2345,weight:70.15}],active:false}],analyticsDate:20140630}
I have to parse sentMsg parameter such as I am able to read each variable individually. For eg, i should be able to read data.requestorName, companyName. I am not able to find a way to do it.
request.getParameter("sentMsg") always return String.
Tried parsing it through json-simple
JSONParser jp = new JSONParser();
try {
Object obj = jp.parse(sentMsg);
JSONArray ja = (JSONArray)obj;
} catch (ParseException e) {
e.printStackTrace();
}
But this gives parse exception. I have limitation to use json-simple jar only. Any suggestion on how to do it?
Get the paramter sentMsg from HttpRequest object store it into a string. Split from comma i.e. "," and the last second token would be the json string. You can now parse it using Json simple lib and extract values from it.
Provided you have valid JSON like:
private static String jsonString = "[{name : \"stackOverFlow\"}]";
Convert it to JSONArray like:
JSONArray jsonArray = new JSONArray(jsonString );
Then you can get value out of JSONArray by looping through it:
for (int i = 0; i < jsonArray.length(); i++) { //Iterating over mediaArray
JSONObject media = jsonArray.getJSONObject(i);
String nameFromJSON = media.getString("name");
System.out.println("Name = " + nameFromJSON);
}
Output will be:
//Name = stackOverFlow
I would like to seek help on how to parse this string
{"success":false,"error":{"code":500,"message":"No keyword found."}}
I would want to be able to get the error code and the error message. The only problem I have is finding a regex that could capture the values I'm stuck at
Pattern pattern = Pattern.compile(REGEX?);
Matcher matcher = pattern.matcher(result);
You need to parse it to json and get value not regex as your response is in JSON.
JSONObject message = new JSONObject(yourResponse);
// use myJson as needed, for example
JSONObject error = message.getJSONObject(“error”);
int code = error.getInt(“code”);
String message2 = error.getString(“message”);
In Java, we do not often compile Patterns for such trivial tasks.
Quick Answer
code = Integer.parseInt(result.split("\"")[6].split(",")[0].substring(1));
msg = result.split("\"")[9].split(",")[0];
This won't work if result has commas.
if you want regex, this is it
s = s.replaceAll(".*\"code\":(.+?),.*", "$1");
The org.json library is easy to use. Example code is as below:
JSONObject obj = new JSONObject(" .... ");
int errCode= obj.getJSONObject("error").getInt("code");
This string is in json format, better use a json parser. Try this:
String s = "{\"success\":false,\"error\":{\"code\":500,\"message\":\"No keyword found.\"}}";
JSONObject jsonObject;
try {
jsonObject = new JSONObject(s);
JSONObject error = (JSONObject) jsonObject.get("error");
System.out.println(error.get("message"));
System.out.println(error.get("code"));
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Also have a look at this site.
I am currently writing some code in a servlet that gets data from the database and returns it to the client. What I am having problems with is inserting the array of dates I have collected and adding them to my JSON object that I will return to the client.
Here is the code I'm trying but it keeps giving errors
dates = ClassdatesDAO.getdate(dates);
ArrayList<String> ClassDates = new ArrayList<String>();
ClassDates = dates.getClassdates();
response.setContentType("application/json");
JSONObject Dates = new JSONObject();
Dates.put("dates", new JSONArray(ClassDates));
In my IDE I get this error over the ClassDates in the JSONArray
The constructor JSONArray(ArrayList) is undefined
You are passing ArrayList instance instead of an Array. So, convert the list into an array and then pass it as an argument like this
Dates.put("dates", new JSONArray(ClassDates.toArray(new String[ClassDates.size()])));
Note : json API has a method signature accepting java.util.Collection. So, you are using some other library or older version
JSONObject Dates = new JSONObject();
JSONArray datesJSONArray = new JSONArray();
for (String date : ClassDates)
datesJSONArray.put(date);
try {
Dates.put("dates", datesJSONArray);
} catch (JSONException e) {
e.printStackTrace();
}
I'm trying to convert this JSON string into an array:
{"result":"success","source":"chat","tag":null,"success":{"message":"%message%","time":%time%,"player":"%player%"}}
I would like to output it like this:
<%player%> %message%
I'm very new to java, I came from PHP where you could just do somthing along the lines of:
$result = json_decode($jsonfile, true);
echo "<".$result['success']['player']."> ".$result['success']['message'];
Output: <%player%> %message%
Is there an easy way to do this in java?
I searched for some similar topics but I didn't really understand them. Could someone explain this to me like I'm 5?
Why reinvent the wheel, use GSON - A Java library that can be used to convert Java Objects into their JSON representation and vice-versa
JSON-lib is a good library for JSON in Java.
String jsonString = "{message:'%message%',player:'%player%'}";
JSONObject obj = JSONObject.fromObject(jsonString);
System.out.println("<" + obj.get("message") + ">" + obj.get("player") );
You can also use xStream for doing it which has got a very simple API. Just Google for it.
You can always use the following libraries like:
- Jackson
- GSON
Ok here is the right way to do it Without using any library:
Eg:
JSONArray jarr = api.giveJsonArr();
// giveJsonArr() method is a custom method to give Json Array.
for (int i = 0; i < jarr.length(); i++) {
JSONObject jobj = jarr.getJSONObject(i); // Taking each Json Object
String mainText = new String(); // fields to hold extracted data
String provText = new String();
String couText = new String();
String fDatu = new String();
try {
mainText = jobj.getString("Overview"); // Getting the value of fields
System.out.println(mainText);
} catch (Exception ex) {
}
try {
JSONObject jProv = jobj.getJSONObject("Provider");
provText = jProv.getString("Name");
System.out.println(provText);
} catch (Exception ex) {
}
try {
JSONObject jCou = jobj.getJSONObject("Counterparty");
couText = jCou.getString("Value");
System.out.println(couText);
} catch (Exception ex) {
}
try {
String cloText = jobj.getString("ClosingDate");
fDatu = giveMeDate(cloText);
System.out.println(fDatu);
} catch (Exception ex) {
}
}
As you see you have many alternatives. Here is a simple one from json.org where you find lots of other alternatives. The one they supply them selves is simple. Here is your example:
String json = "{\"result\":\"success\",\"source\":\"chat\",\"tag\":null,\"success\":{\"message\":\"%message%\",\"time\":%time%,\"player\":\"%player%\"}}";
JSONObject obj = new JSONObject(json);
JSONObject success = obj.getJSONObject("success");
System.out.println("<" + success.get("player") + "> "
+ success.get("message"));