Develop Reference

How do i preserve the original order of json with JSONArray

I am using the JSONArray object and I am passing to the constructor of that object a string. The string that I'm passing is
[{\"x\":18.4300,\"y\":30.4700,\"w\":53.0900,\"fontSize\": 11,\"bold\": 0,\"charcount\": 22,\"id\": 349133}].
After out-printing the json object, I get the following:
[{"charcount":22,"w":53.09,"x":18.43,"y":30.47,"fontSize":11,"bold":0,"id":349133}].
Can I get an example in code of how I can preserve the order of the original json string?

You can use a an ordered collection to parse your json to keep it's order.
A sample for your json:
String json = "[{\"x\":18.4300,\"y\":30.4700,\"w\":53.0900,\"fontSize\": 11,\"bold\": 0,\"charcount\": 22,\"id\": 349133}]";
Gson gson = new Gson();
Type type = new TypeToken<Set<LinkedTreeMap<String, Object>>>() {}.getType();
Set<LinkedTreeMap<String, Object>> myMap = gson.fromJson(json, type);
System.out.println(json);
System.out.println(myMap);

How to convert JSON to HashMap and compare them?

I have a json stored in a DB like this,
"supported_iso_codes":[
{
"EUR": "978",
"USD": "840"
}
],
To access this in my app code, I do something like this..
getISOProfileDB.getSupportedISOCodes();
I have a string which the user inputs(provides input string like EUR, USD,etc). How can I convert the above json to a HashMap and compare it with another string? What I am trying to achieve is,
Compare Key part of json to user input string(EUR).
If both of them match,
Parse the value part of json and store it in a variable.
Below is what I'm trying to achieve,
tran.setCurrency(hashMapOfJson.get(currencyString));

Use Gson :
dependencies {
compile 'com.google.code.gson:gson:2.2.4'
}
And then :
Map<String, Object> supported_iso_codes = new Gson().fromJson(getISOProfileDB.getSupportedISOCodes(), new TypeToken<HashMap<String, Object>>() {}.getType());

You can do something like this
Gson gson = new Gson();
Type type = new TypeToken<List<Map<String, String>>>(){}.getType();
final ArrayList<HashMap<String,String>> isoCodesMapList = gson.fromJson(data, type);
System.out.println(arrayList);
then for getting the user selected currency you can do
isoCodesMapList.get(userSelectedCurrency);
Hope this helps:)

You should consider using JSONObject (Jsonobject.org) or Gson.

toString() changes the curly braces into square?

I have the following construct in my code for the following JSON
SomeVariable =
{
"FirstVar":{
"service1":"value1"
}
}
For this I have the following
code in Java
Map<String,String> internal_service_var = new HashMap<String,String>();
internal_service_endpoint.put("service1","value1");
Map<String, String> first_var = new HashMap<String,String>();
first_var.put("FirstVar", internal_service_var.entrySet().toString());
Map<String, String> some_var = new HashMap<String, String>();
some_var.put("SomeVariable", first_var.entrySet().toString());
Here is how I try to use it in the JSON to send over wire
Note that the value of the property in the JSON needs to be a String
JSONObject json = new JSONObject
json.put("var", some_var);
This sets the 'var' property in the json to be
[SomeVariable = [ "FirstVar":[ "service1":"value1"]]]
Instead of
SomeVariable = { "FirstVar":{ "service1":"value1"}}
What am I missing?

The toString() of HashMap does not return the data in JSON format. If you want JSON objects use only JSONObject.
Alternatively, use xstream:
XStream xstream = new XStream(new JettisonMappedXmlDriver());
xstream.setMode(XStream.NO_REFERENCES);
String jsonRepresentation = map.toXML();
jsonRepresentation will have your json. Yes, for reasons only known to ancient sages, xstream uses toXML for serialization. It's misnamed, and unlikely to change to anything else.

Json: Deserialization error while using Gson library

I have json string that should be converted back to a Map type.
Json used:
String jsonString = "{
"varA": "<math><mrow><mn>8</mn></mrow></math>",
"varB": "<math><mrow><mi>m</mi></mrow></math>",
"ans": "<math><mrow><mn>8</mn><mo>⁢</mo><mi>m</mi></mrow></math>"
}"
Code that converts json to Map:
Map<String, String> variableMap = gson.fromJson(jsonString, new TypeToken<Map<String,String>>(){}.getType());
Error:
[ERROR] The JsonDeserializer StringTypeAdapter failed to deserialize json object {"varA":"<math><mrow><mn>8</mn></mrow></math>","varB":"<math><mrow><mi>m</mi></mrow></math>","ans":"<math><mrow><mn>8</mn><mo>⁢</mo><mi>m</mi></mrow></math>"} given the type class java.lang.String
I know it has something to do with the type, but I have indicated that the type will be String explicitly in the type token.
The gson object is declared as follows:
Gson gson = new GsonBuilder().disableHtmlEscaping().create();

You have to escape the quotes that delimit the JSON string values contained within your Java string. In fact your example is not a valid Java program - Java lacks multi-line strings, for starters.
The following snippet runs just fine (angle brackets and the Unicode character turn out to be innocuous):
public static void main(String[] args) {
String jsonString = "{\"varA\": \"<math><mrow><mn>8</mn></mrow></math>\", \"varB\": \"<math><mrow><mi>m</mi></mrow></math>\", \"ans\": \"<math><mrow><mn>8</mn><mo>⁢</mo><mi>m</mi></mrow></math>\"}";
Map<String, String> variableMap = new Gson().fromJson(jsonString, new TypeToken<Map<String,String>>(){}.getType());
System.out.println("foo");
}

It is working when you use Map.class instead of new TypeToken<Map<String,String>>(){}.getType(). See my little example:
Gson gson = new GsonBuilder().disableHtmlEscaping().create();
Map<String, String> map = new HashMap<String, String>();
map.put("varA", "<math><mrow><mn>8</mn></mrow></math>");
map.put("varB", "<math><mrow><mi>m</mi></mrow></math>");
map.put("ans", "<math><mrow><mn>8</mn><mo>⁢</mo><mi>m</mi></mrow></math>");
String json = gson.toJson(map);
System.out.println(json);
System.out.println(gson.fromJson(json, Map.class));
It prints:
{
"varB":"<math><mrow><mi>m</mi></mrow></math>",
"ans":"<math><mrow><mn>8</mn><mo>⁢</mo><mi>m</mi></mrow></math>",
"varA":"<math><mrow><mn>8</mn></mrow></math>"
}
{varB=<math><mrow><mi>m</mi></mrow></math>, ans=<math><mrow><mn>8</mn><mo>⁢</mo><mi>m</mi></mrow></math>, varA=<math><mrow><mn>8</mn></mrow></math>}

Possibility of using Generic function to convert any Java Object to JSON

I would like to know if it is possible to convert any Java object to JSON object. Currently I have the following code.
JSONArray data = new JSONArray();
for (User user : users) {
JSONArray row = new JSONArray();
row.put(user.getId()).put(user.getUserName()).put(user.isEnabled());
data.put(row);
}
The current issue is different object (e.g. User and Admin) will have different property, thus the above code will work for other object. I am thinking of putting a similar code in my GenericHibernateDAO in order to automatically convert any list into a json list.

You can serialize your java object to json object. There are n number of library is available ex gson, jettyson, flexjson etc.
GSON example -
Gson gson = new Gson();
Collection<Integer> ints = Lists.immutableList(1,2,3,4,5);
(Serialization)
String json = gson.toJson(ints); ==> json is [1,2,3,4,5]

Here i exemplify the way of converting POJO to json using jackson
create your pojo : User user = new User();
you can set or get values to/from user
create ObjectMapper : ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(user);// object to json