i found many examples to parse java object to Json.
Thanks for that.But i have one issue, i want Json in following format
{
"parent":
{
"sub-parent-1":
{
"child-1": 1,
"child-2": 2
},
"sub-parent-2":
{
"child-2": 3
}
}
}
Is it possible with java.
Please answer.Thanks in advanced..
Create Current Json String as in Java :
JSONObject parent = new JSONObject();
JSONObject subparentone = new JSONObject();
JSONObject subparenttwo = new JSONObject();
subparentone.put("child-1", "1");
subparentone.put("child-2", "2");
subparenttwo.put("child-2", "3");
parent.put("sub-parent-1", subparentone);
parent.put("sub-parent-2", subparenttwo);
JSONObject finalparent = new JSONObject();
finalparent.put("parent", parent);
and finalparent JsonObject output as:
{
"parent": {
"sub-parent-1": {
"child-1": 1,
"child-2": 2
},
"sub-parent-2": {
"child-2": 3
}
}
}
I have created class for parent and pass child to it. And convert that parent class into Json using Gson.
Related
So, I tried something with java which looks like this, but the output does not look nice.
One of the code-examples I tried to make a json file with:
String name = "usericals.json";
JSONObject jsonObj = new JSONObject();
JSONArray scene = new JSONArray();
JSONArray element = new JSONArray();
jsonObj.put("scene", scene);
for (int i = 0; i < 1; i++) {
for (int ii = 0; ii < 1; ii++) {
element.put(write);
}
jsonObj.put("element", element);
}
scene.put(element);
try (PrintWriter writer = new PrintWriter("new.json", "UTF-8")) {
writer.write(jsonObj.toString(4));
} catch (Exception ex) {
System.out.println("exception " + ex);
}
I wanted to make a json file which looks like this but I cannot get it right. I am creating with my code above only arrays. Does anyone have an idea or suggestion?
The JSON File I want:
{
"scene": [
{
"id": 0,
"calendar_event": "urlaub",
"element": [
{
"anything": ""
},
{
"anything": ""
}
]
},
{
"id": 1,
"calendar_event": "urlauburlaub",
"element": [
{
"anything": ""
},
{
"anything": ""
}
]
},
{
"id": 2,
"calendar_event": "urlauburlauburlaub",
"element": [
{
"anything": ""
},
{
"device": "",
"anything": ""
}
]
},
{
"id": 3,
"calendar_event": "urlauburlauburlauburlaub",
"element": [
{
"anything": ""
},
{
"anything": ""
}
]
}
]
}
I suggest using library for that. Jackson or GSON would be a good choice.
Instead of manually creating json field by field you could create POJOs and then use Jackson's ObjectMapper. Example:
public class Car {
private String color;
private String type;
// standard getters setters
}
and then
ObjectMapper objectMapper = new ObjectMapper();
Car car = new Car("yellow", "renault");
objectMapper.writeValue(new File("target/car.json"), car);
Which will give
{"color":"yellow","type":"renault"}
Google has a lot of jackson tutorials!
Use JSONObject recursively. Try something like this (I add some extra indentation so it can be readed easily, but on real projects better use functions instead):
JSONObject json = new JSONObject();
JSONArray scene = new JSONArray();
JSONObject node = new JSONObject();
node.put("id", 0);
node.put("calendar_event", "urlaub");
JSONArray element = new JSONArray();
JSONObject enode = new JSONObject();
enode.put("anything", "");
element.add(enode);
//...
node.put("element", element);
scene.add(node);
json.put("scene", scene);
//...
Note like this you generate manually the JSONs, but there are other libraries that scan objects to generate jsons. Depending on your needs, it could be easer, but remember that making so you are going to overhead everything because you are going to need to hold in memory two copies of the same tree. Also dealing with hierarchical structures maybe a problem using plain java objects.
I have this JSON object that I've created using GSON:
{
"data": {
"isDeleted": false,
"period": 201601,
"columnMap": {
"1c49eb80-7b53-11e6-bc4b-afbeabb62718": "5000",
"1c49eb80-7b52-11e6-bc4b-afbeabb62718": "hello",
"03a534c0-a7f1-11e6-9cde-493bf5c47f4": "AUS",
"03a534c0-a7fa-11e6-9cde-493bf5c47f4": "123"
}
}
}
But my requirement is for it to look like
{
"data": {
"isDeleted": false,
"period": 201601,
"1c49eb80-7b53-11e6-bc4b-afbeabb62718": "5000",
"1c49eb80-7b52-11e6-bc4b-afbeabb62718": "hello",
"03a534c0-a7f1-11e6-9cde-493bf5c47f4": "AUS",
"03a534c0-a7fa-11e6-9cde-493bf5c47f4": "123"
}
}
}
How do I solve this, because all the values in "columnMap" are generated dynamically.
You need to create instance updateJsonObj of JsonObject to update key and value of columnMap using for each loop. Following code snippet is the solution :
String json = "{ \"data\": {\"isDeleted\": false,\"period\": 201601,"
+ "\"columnMap\": {\"1c49eb80-7b53-11e6-bc4b-afbeabb62718\": \"5000\","
+ "\"1c49eb80-7b52-11e6-bc4b-afbeabb62718\": \"hello\","
+ "\"03a534c0-a7f1-11e6-9cde-493bf5c47f4\": \"AUS\", "
+ "\"03a534c0-a7fa-11e6-9cde-493bf5c47f4\": \"123\"}}}";
Gson gson = new Gson();
JsonObject root = new JsonParser().parse(json).getAsJsonObject();
JsonElement dataElement = root.get("data");
// cobj has value of colummMap of json data
JsonObject cobj = (JsonObject) root.get("data").getAsJsonObject().get("columnMap");
JsonObject updateJsonObj = root;
// remove columnMap node as you wanted !
updateJsonObj.get("data").getAsJsonObject().remove("columnMap");
for (Entry<String, JsonElement> e : cobj.entrySet()) {
//update updateJsonObj root node with key and value of columnMap
updateJsonObj.get("data").getAsJsonObject().addProperty(e.getKey(), e.getValue().getAsString());
}
String updateJson = gson.toJson(updateJsonObj);
System.out.println(updateJson);
I want to make an array of product objects from a json file which is currently a String.
{
"invoice": {
"products": {
"product": [
{
"name": "Food",
"price": "5.00"
},
{
"name": "Drink",
"price": "2.00"
}
]
},
"total": "7.00"
}
}
...
String jsonString = readFile(file);
JsonParser parser = new JsonParser();
JsonObject jsonObject = parser.parse(jsonString).getAsJsonObject();
JsonArray jsonArray = jsonObject.getAsJsonArray("product");
the line below give me: java.lang.NullPointerException
for(JsonElement element: jsonArray) {
//do stuff
System.out.println(element);
}
some code goes here...
product = new Product(name, price);
List<Product> products = new ArrayList<Product>();
products.add(product);
You have to traverse the whole JSON string to get to the "product" part.
JsonArray jsonArray = jsonObject.get("invoice").getAsJsonObject().get("products").getAsJsonObject().get("product").getAsJsonArray();
I would recommend that you create a custom deserializer as described in the second answer to this question: How do I write a custom JSON deserializer for Gson? This will make it a lot cleaner, and let you handle improper JSON and make it easier in case your JSON ever changes.
I think you can use Gson library for this
You can find the project and the documentation at : https://github.com/google/gson/blob/master/README.md
try
String jsonString = readFile(file);
JsonParser parser = new JsonParser();
JsonObject invoice = parser.parse(jsonString).getAsJsonObject();
JsonObject products = invoice.getAsJsonObject("products");
JsonArray jsonArray = products.getAsJsonArray("product");
I am try to decode a JSON string as below
{
"id_value": [
{
"id": "1.1.1.1",
"value": "v1"
},
{
"id": "1.1.1.2",
"value": "v2"
}
]
}
Which is basically a list of id_value object. IdValue is a POJO class with a string variable of id and value.
I am able to decode the JSON string , when I passed in JSON without the list name , as below.
[
{
"id": "1.1.1.1",
"value": "v1"
},
{
"id": "1.1.1.2",
"value": "v2"
}
]
My JAVA code is as below :
String jsonString1 = "{\"id_value\": [{\"id\": \"1.1.1.1\",\"value\": \"v1\"},{\"id\": \"1.1.1.2\",\"value\": \"v2\"}]}";
String jsonString2 = "[{\"id\": \"1.1.1.1\",\"value\": \"v1\"},{\"id\": \"1.1.1.2\",\"value\": \"v2\"}]";
List<IdValue> idValues = null;
try {
Gson gson = new Gson();
idValues = gson.fromJson(jsonString2, new TypeToken<List<IdValue>>(){}.getType());
}
catch (Exception e) {
e.printStackTrace();
}
System.out.println(idValues);
My code works well with jsonString2 , but I am getting the below exception with jsonString1. Both of them are lists , but why it is failing for one and working for other.
com.google.gson.JsonParseException: The JsonDeserializer com.google.gson.DefaultTypeAdapters$CollectionTypeAdapter#67ac19 failed to deserialize json object {"id_value":[{"id":"1.1.1.1","value":"v1"},{"id":"1.1.1.2","value":"v2"}]} given the type java.util.List<com.something.json.IdValue>
Any inputs would be helpful.
Thanks !!
jsonString2 represents a List<IdValue>
jsonString1 represents a Map<String, List<IdValue>>
So, to process jsonString1 you need:
Map<String, List<IdValue>> map = gson.fromJson(json, new TypeToken<Map<String, List<IdValue>>>(){}.getType());
List<idValue> idValues = map.get("id_value");
Here is more general way to get your IdValues from jsonString1 even if there are another entries in it:
Gson gson = new Gson();
JsonParser parser = new JsonParser();
String jsonString1 = "{\"id_value\": [{\"id\": \"1.1.1.1\",\"value\": \"v1\"},{\"id\": \"1.1.1.2\",\"value\": \"v2\"}]}";
JsonElement e = parser.parse(jsonString1);
JsonArray idValueArray = e.getAsJsonObject().getAsJsonArray("id_value");
List<IdValue> idValues = gson.fromJson(idValueArray, new TypeToken<List<IdValue>>(){}.getType());
id_value isn't part of your IdValue POJO. So the TypeToken of List does not know how to map the id_value piece of the JSON string.
Because jsonString1's deserializing type is not same with jsonString2's. If you want to use same deserializing type, you should first do substring.
jsonString1 = jsonString1.substring(s.indexOf("["));
jsonString1 = jsonString1.substring(0, s.lastIndexOf("]") + 1);
I am facing issue in looping in the following code,i am passing a list of forms to it,i am not sure what is going wrong,i need the output as but i am getting only the last form_id.I have this code to get this output as ,here i am passing a list of forms and getting the json as output. Please let me know where am i going wrong.
output :
{
"forms": [
{ "form_id": "1", "form_name": "test1" },
{ "form_id": "2", "form_name": "test2" }
]
}
code :
public class MyFormToJSONConverter {
public JSONObject getJsonFromMyFormObject(List<Form> form) {
JSONObject responseDetailsJson = new JSONObject();
JSONArray jsonArray = null;
List<JSONArray> list = new ArrayList<JSONArray>();
System.out.println(form.size());
for (int i = 0; i < form.size(); i++) {
JSONObject formDetailsJson = new JSONObject();
formDetailsJson.put("form_id", form.get(i).getId());
formDetailsJson.put("form_name", form.get(i).getName());
formDetailsJson.put("desc",
form.get(i).getFormDescription());
jsonArray = new JSONArray();
jsonArray.add(formDetailsJson);
list.add(jsonArray);
}
for (JSONArray json : list) {
responseDetailsJson.put("form", json);
}
return responseDetailsJson;
}
Your problem is here:
for (JSONArray json : list) {
responseDetailsJson.put("form", json);
}
will overwrite all of the previous values with the next value (a single JSON object). You want
responseDetailsJson.put("form", list);
You probably should also get rid of this:
jsonArray = new JSONArray();
jsonArray.add(formDetailsJson);
list.add(jsonArray);
That will give you:
{
"forms": [
[{ "form_id": "1", "form_name": "test1" }],
[{ "form_id": "2", "form_name": "test2" }]
]
}
All told, I think you want:
JSONObject responseDetailsJson = new JSONObject();
List<JSONObject> list = new ArrayList<JSONObject>();
System.out.println(form.size());
// List.get will be very inefficient if passed a LinkedList
// instead of an ArrayList.
for (Form formInstance:form) {
JSONObject formDetailsJson = new JSONObject();
formDetailsJson.put("form_id", formInstance.getId());
formDetailsJson.put("form_name", formInstance.getName());
formDetailsJson.put("desc",
formInstance.getFormDescription());
list.add(formDetailsJson);
}
responseDetailsJson.put("form", list);
JSON objects are essentially key/value pairs. In your code you are doing:
for (JSONArray json : list)
{
responseDetailsJson.put("form", json);
}
You're overwriting the same key each time.