How do I parse JSON in Android? [duplicate]
How do I parse a JSON feed in Android?
3 Answers 3
Android has all the tools you need to parse json built-in. Example follows, no need for GSON or anything like that.
Get your JSON:
Assume you have a json string
Create a JSONObject:
If your json string is an array, e.g.:
then you should use JSONArray as demonstrated below and not JSONObject
To get a specific string
To get a specific boolean
To get a specific integer
To get a specific long
To get a specific double
To get a specific JSONArray:
To get the items from the array
Writing JSON Parser Class
Parsing JSON Data
Once you created parser class next thing is to know how to use that class. Below i am explaining how to parse the json (taken in this example) using the parser class.
2.1. Store all these node names in variables: In the contacts json we have items like name, email, address, gender and phone numbers. So first thing is to store all these node names in variables. Open your main activity class and declare store all node names in static variables.
2.2. Use parser class to get JSONObject and looping through each json item. Below i am creating an instance of JSONParser class and using for loop i am looping through each json item and finally storing each json data in variable.
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Учебник по JSON для Android: создание и анализ данных JSON
В этом руководстве описывается, как использовать JSON с Android . JSON расшифровывается как (Java Script Object Notation). Это простой и легкий формат обмена данными, который может быть легко прочитан людьми и машинами. JSON — это текстовый формат, не зависящий от языка. Он представляет данные в текстовом формате, чтобы их можно было легко проанализировать.
Введение в JSON
JSON использует две разные структуры:
- Коллекция пары имя / значение
- массив
Первую структуру можно использовать для моделирования объекта, поскольку объект представляет собой набор атрибутов, которые содержат некоторые значения. Массив может использоваться для моделирования списка, массива объектов и так далее. Таким образом, используя эти две структуры, мы можем передавать данные между двумя машинами простым и эффективным способом. В последнее время JSON пользуется большим успехом, и большинство доступных API поддерживает формат JSON. Давайте посмотрим, как мы можем представлять данные в формате JSON.
Объект в JSON моделируется с помощью , а его атрибуты можно моделировать с помощью name: value pair.Value, в свою очередь, может быть объектом, массивом или «простым» значением, например, примитивным значением (int, Строка, логическое значение и т. Д.).
Так что если у нас есть, например, класс Java, как:
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Android — how to parse JsonArray from string?
I am trying to parse a json array from json string but it always throws the exception data of type java.lang.String cannot be converted to JSONArray .
Please tell me if I make any mistake.
Here is my codes to get Json from server:
here is codes to parse JsonArray:
Here is my json string:
3 Answers 3
This is how to initialize a JSON parser:
That will give you the entire string as a Json Object. From there, pull out an individual array as a JsonArray, like this:
To access each «LotPrizes» you can use for loop logic:
EDIT: Final code after your JSON edit:
This code is functional and I’m using an almost identical version in my code. Hope this (finally) works for you.
Hi @Caerulius, Harish, ρяσѕρєя K, Hot Licks , and all. Finally, after 2 days of headache and 2 sleepless nights, I solved the issue. And because you spend your valued time to discuss with me, I see that I have to tell you the root cause. That’s my responsibility.
First of all, I am a senior android developer. So, I at least know about JSON basic, I know how to parse data from JSON string, and I know many useful online tools to validate it. I confirm that the JSON string I got from server is valid.
As I told in my question, I used final String result = EntityUtils.toString(entity); to get JSON string from HttpEntity object. I have used this many times in the past and it worked. No problem. But, in this case, it’s not. The original JSON string like this:
But what I got like this:
This string is similar with the constant string which we may declare as below:
It’s a valid string, but not a valid JSON String.
To fix this issue, I change the way to get JSON string, and remove unnecessary characters like this:
Now, the json variable contain JSON string which I can parse correctly. I think this should a bug of HttpEntity library.
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How to convert HashMap to json Array in android?
I want to convert HashMap to json array my code is as follow:
I have tried this but it didn’t work. Any solution?
5 Answers 5
Creates a new JSONObject by copying all name/value mappings from the given map.
Parameters copyFrom a map whose keys are of type String and whose values are of supported types.
Throws NullPointerException if any of the map’s keys are null.
get the json array from the JSONObject
Edit:
Edit:(If found Exception then You can change as mention in comment by @krb686)
Since androiad API Lvl 19, you can simply do new JSONObject(new HashMap()) . But on older API lvls you get ugly result(simple apply toString to each non-primitive value).
I collected methods from JSONObject and JSONArray for simplify and beautifully result. You can use my solution class:
Then if you apply mapToJson() method to your Map, you can get result like this:
A map consists of key / value pairs, i.e. two objects for each entry, whereas a list only has a single object for each entry. What you can do is to extract all Map.Entry and then put them in the array:
Alternatively, sometimes it is useful to extract the keys or the values to a collection:
Note: If you choose to use the keys as entries, the order is not guaranteed (the keySet() method returns a Set ). That is because the Map interface does not specify any order (unless the Map happens to be a SortedMap ).
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How to Parse JSON Array with Gson
I want to parse JSON arrays and using gson. Firstly, I can log JSON output, server is responsing to client clearly.
Here is my JSON output:
I tried this structure for parsing. A class, which depends on single array and ArrayList for all JSONArray.
When I try to use gson no error, no warning and no log:
What’s wrong, how can I solve?
9 Answers 9
You can parse the JSONArray directly, don’t need to wrap your Post class with PostEntity one more time and don’t need new JSONObject().toString() either:
Hope that helps.
I was looking for a way to parse object arrays in a more generic way; here is my contribution:
To conver in Object Array
To convert as post type
To read it as List of objects TypeToken can be used
Some of the answers of this post are valid, but using TypeToken, the Gson library generates a Tree objects whit unreal types for your application.
To get it I had to read the array and convert one by one the objects inside the array. Of course this method is not the fastest and I don’t recommend to use it if you have the array is too big, but it worked for me.
It is necessary to include the Json library in the project. If you are developing on Android, it is included:
You can easily do this in Kotlin using the following code:
Basically, you only need to provide an Array of YourClass objects.
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