How to convert the following json string to java object?

JavaJsonJackson

Java Problem Overview


I want to convert the following JSON string to a java object:

String jsonString = "{
  "libraryname": "My Library",
  "mymusic": [
    {
      "Artist Name": "Aaron",
      "Song Name": "Beautiful"
    },
    {
      "Artist Name": "Britney",
      "Song Name": "Oops I did It Again"
    },
    {
      "Artist Name": "Britney",
      "Song Name": "Stronger"
    }
  ]
}"

My goal is to access it easily something like:

(e.g. MyJsonObject myobj = new MyJsonObject(jsonString)
myobj.mymusic[0].id would give me the ID, myobj.libraryname gives me "My Library").

I've heard of Jackson, but I am unsure how to use it to fit the json string I have since its not just key value pairs due to the "mymusic" list involved. How can I accomplish this with Jackson or is there some easier way I can accomplish this if Jackson is not the best for this?

Java Solutions


Solution 1 - Java

No need to go with GSON for this; Jackson can do either plain Maps/Lists:

ObjectMapper mapper = new ObjectMapper();
Map<String,Object> map = mapper.readValue(json, Map.class);

or more convenient JSON Tree:

JsonNode rootNode = mapper.readTree(json);

By the way, there is no reason why you could not actually create Java classes and do it (IMO) more conveniently:

public class Library {
  @JsonProperty("libraryname")
  public String name;

  @JsonProperty("mymusic")
  public List<Song> songs;
}
public class Song {
  @JsonProperty("Artist Name") public String artistName;
  @JsonProperty("Song Name") public String songName;
}

Library lib = mapper.readValue(jsonString, Library.class);

Solution 2 - Java

Check out Google's Gson: http://code.google.com/p/google-gson/

From their website:

Gson gson = new Gson(); // Or use new GsonBuilder().create();
MyType target2 = gson.fromJson(json, MyType.class); // deserializes json into target2

You would just need to make a MyType class (renamed, of course) with all the fields in the json string. It might get a little more complicated when you're doing the arrays, if you prefer to do all of the parsing manually (also pretty easy) check out http://www.json.org/ and download the Java source for the Json parser objects.

Solution 3 - Java

Gson gson = new Gson();
JsonParser parser = new JsonParser();
JsonObject object = (JsonObject) parser.parse(response);// response will be the json String
YourPojo emp = gson.fromJson(object, YourPojo.class); 

Solution 4 - Java

Gson is also good for it: http://code.google.com/p/google-gson/

" Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of. "

Check the API examples: https://sites.google.com/site/gson/gson-user-guide#TOC-Overview More examples: http://www.mkyong.com/java/how-do-convert-java-object-to-from-json-format-gson-api/

Solution 5 - Java

Underscore-java (which I am the developer of) can convert json to Object.

import com.github.underscore.U;

    String jsonString = "{\n" +
            "        \"libraryname\":\"My Library\",\n" +
            "                \"mymusic\":[{\"Artist Name\":\"Aaron\",\"Song Name\":\"Beautiful\"},\n" +
            "        {\"Artist Name\":\"Britney\",\"Song Name\":\"Oops I did It Again\"},\n" +
            "        {\"Artist Name\":\"Britney\",\"Song Name\":\"Stronger\"}]}";
    Map<String, Object> jsonObject = U.fromJsonMap(jsonString);
    System.out.println(jsonObject);

    // {libraryname=My Library, mymusic=[{Artist Name=Aaron, Song Name=Beautiful}, {Artist Name=Britney, Song Name=Oops I did It Again}, {Artist Name=Britney, Song Name=Stronger}]}

    System.out.println(U.<String>get(jsonObject, "mymusic[0].Artist Name"));
    // Aaron

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionRolandoView Question on Stackoverflow
Solution 1 - JavaStaxManView Answer on Stackoverflow
Solution 2 - JavajpalmView Answer on Stackoverflow
Solution 3 - JavaPraveen KokkulaView Answer on Stackoverflow
Solution 4 - Javauser1352498View Answer on Stackoverflow
Solution 5 - JavaValentyn KolesnikovView Answer on Stackoverflow