I'm requesting data from a server which returns data in the JSON format. The JSON response looks like this:. Luckily you can accomplish it with a custom deserializer. The messiness inside the handlePrimitive method is for making sure you only ever get a Double or an Integer or a Long, and probably could be better, or at least simplified if you're okay with getting BigDecimals, which I believe is the default.
I'm not sure why this is not the default behavior in gson, since it is in most other semi-structured serialization libraries With google's Gson 2. Which returns a Map of type com. LinkedTreeMap and works recursively on nested objects, arrays, etc.
I ran the OP example like so simply replaced double- with single-quotes and removed whitespace :. To fix this, just declare the result as LinkedTreeMap type.
Kotlin – Convert object to/from JSON string using Gson
Example below:. I had the exact same question and ended up here. I had a different approach that seems much simpler maybe newer versions of gson? Replace KioskStatusResource to your class and Integer to your key class. I have overcome a similar problem with a Custom JsonDeSerializer. I tried to make it a bit generic but still not enough. It is a solution though that fits my needs. The con with this solution, is that my Map's key is always of Type "String". However by chaning some things someone can make it generic.
In addition, i need to say, that the value's class should be passed in the constructor. So the method getMyType in my code returns the type of the Map's values, which was passed in the constructor.Welcome back to another blog post in our Gson series.
After reviewing the basics of Gson, model annotations and mapping of nested objects, we'll go on to a core feature: mapping of Arrays and Lists. Almost every data model out there utilizes some form of list. Fortunately, Gson makes it really easy to deal with them. As you know, we're publishing a whole series about Gson. If you're interested in another topic, check out our series outline:. Mapping of Nested Objects. Mapping of Arrays and Lists of Objects. Multiple Deserialization Names with SerializedName.
Cant parse simple json string (android) [closed]
How to Ignore Fields with Expose. Force Serialization of null Values. Relax Gson with Lenient. Mapping of Circular References. Custom Serialization for Simplification Part 1. Custom Deserialization Basics. Custom Instance Creator. Customizing De Serialization via JsonAdapter. Custom Deserialization for Calculated Fields.
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I am using Google Gson. To make the use more generic - you will find that Gson's javadocs are pretty clear and helpful. In my first gson application I avoided using additional classes to catch values mainly because I use json for config matters. Adding getters and setters is pointless for basic data containers.
You can create corresponding java classes for the json objects. The integer, string values can be mapped as is. Json can be parsed like this.
You can use a separate class to represent the JSON object and use SerializedName annotations to specify the field name to grab for each data member:. With this approach, you can reuse the Response class to add any other additional fields to pick up other data members you might want to extract from JSON -- in case you want to make changes to get results for, say, multiple translations in one call, or to get an additional string for the detected source language.
Using Gson to Solve I would create a class for individual parameter in the json String. Alternatively you can create one main class called "Data" and then create inner classes similarly. I created separate classes for clarity. In the class JsonParsing the method "parse" we call gson. Some good examples and articles.
You can use a JsonPath query to extract the value. And with JsonSurfer which is backed by Gson, your problem can be solved by simply two line of code! Learn more.Go to Maven Repository and download. Because the object we want to parse JSON to is an array-like object.
To get Type of an Arraywe use TypeToken. For example, to create a type literal for Arraywe create an empty anonymous inner class like this:. The major difference among these Type is that: — Array has a fixed size, but it is mutable.
If you want to get pretty JSON, you can use an additional package called com. GsonBuilder with setPrettyPrinting and create method. Hi, thank you for pointing out the error. This is just a typo when using code syntax highlight plugin. I fixed it, now you can check it again. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Necessary cookies are absolutely essential for the website to function properly.
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Gson – Serialize and deserialize HashMap containing custom objects
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These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may have an effect on your browsing experience.Tag: javaphpandroidjson. Sorry for my English. I can't send json to server. I think this is error, but I can fix it. Below is my error:. Then we use realpath which conveniently returns false if file does not exist.
All you have to do is specify a relative Don't do that. It's effectively forging the from address and will fail SPF checks. Instead, use your own address as the From address, and add the submitted address as a reply-to address. Ok, so i tried to decypher what you meant with your Question. To Clarify: He has this one page setup.
When clicked, he wants the About Section to be shown. All in all it is impossible for Correct me if I'm wrong. Then it's just a matter You done need to do anything with your controller. In your MainActivity. That;s why you are geting nullpointerexception. No, we cannot by definition.Also, it can used to convert the JSON string into equivalent java object. There are some other java libraries also capable of doing this conversion, but Gson stands among very few which does not require any pre-annotated java classes OR sourcecode of java classes in any way.
Gson also support the old java classes which had not support of generics in them for type information. It just work with these legacy classes smoothly. In this gson tutorialI am giving few examples of very common tasks you can perform with Gson. Gson object can be created in two ways. First way gives you a quick Gson object ready for faster coding, while second way uses GsonBuilder to build a more sophisticated Gson object. When using GsonBuilderthere are plenty of other useful options you can provide to Gson object.
Go ahead and check them out. In most of the cases, Gson library is smart enough to create instances even if any class does not provide default no-args constructor. But, if you found any problem using a class having no-args constructor, you can use InstanceCreator support.
You need to register the InstanceCreator of a java class type with Gson first before using it. To use Department class correctly, we need to register an InstanceCreator for Department as below:. In that case, we need to write custom serializer and deserializer of that java type.
In our example, I am writing serializer and deserializer for java. Now you can register these serializer and deserializer with GsonBuilder as below:. This means that there will not be any white-space in the output JSON structure. This is excellent feature you can use, if the class file you are working has been modified in different versions and fields has been annotated with Since.
All you need to do is to use setVersion method of GsonBuilder. Drop a comment is you have any query or feedback. A family guy with fun loving nature. Love computers, programming and solving everyday problems.
Find me on Facebook and Twitter. Some great code examples on various usage of Gson! Nice article! I have a basic question if anyone can please answer — What is the advantage of having corresponding Java classes for JSON response? When we can read and write using JSON libraries. Im not able to figure out exactly why it is needed. Any example or link along will be helpful Thanks. All such libraries do one common thing — they convert between java classes and JSON.
In fact, you asked the opposite question — in any java program, you have java classes anyway whether you have JSON or not … question should be why you need JSON??
Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Is there a way to convert a String containing json to a HashMap, where every key is a json-key and the value is the value of the json-key?
The json has no nested values. I am using the Gson lib. Learn more. Gson to HashMap Ask Question. Asked 7 years, 1 month ago. Active 4 years, 1 month ago. Viewed 51k times. Matt Ball k 81 81 gold badges silver badges bronze badges. Daniel Amerbauer Daniel Amerbauer 1 1 gold badge 4 4 silver badges 7 7 bronze badges.
MattBall Seems a pretty unfriendly welcome to a new user. Looking at the answer, it is not at all obvious, and hardly simple. Who uses TypeToken for anything, ever? I'm not really sure what you mean by "a pretty unfriendly welcome. MattBall You had a comment about asking what had been tried with a link and saying that the question was pretty simple. Related stackoverflow. Active Oldest Votes. No unnecessary object creation.
Matt Ball Matt Ball k 81 81 gold badges silver badges bronze badges. What's the import for Type? It gives dozens of options.
This works, but your value type is not respected -- everything is treated as strings. XaeroDegreaz the question subtly suggests that the values should be strings as well, but sure.
Ricardo Fodra Ricardo Fodra 36 5 5 bronze badges.