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);
Answer from StaxMan on Stack OverflowNo 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);
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.
Parsing JSON Object in Java - Stack Overflow
How to parse JSON in Java - Stack Overflow
java - Parse json to object - Stack Overflow
Converting Json to Java object
Videos
I'm assuming you want to store the interestKeys in a list.
Using the org.json library:
JSONObject obj = new JSONObject("{interests : [{interestKey:Dogs}, {interestKey:Cats}]}");
List<String> list = new ArrayList<String>();
JSONArray array = obj.getJSONArray("interests");
for(int i = 0 ; i < array.length() ; i++){
list.add(array.getJSONObject(i).getString("interestKey"));
}
public class JsonParsing {
public static Properties properties = null;
public static JSONObject jsonObject = null;
static {
properties = new Properties();
}
public static void main(String[] args) {
try {
JSONParser jsonParser = new JSONParser();
File file = new File("src/main/java/read.json");
Object object = jsonParser.parse(new FileReader(file));
jsonObject = (JSONObject) object;
parseJson(jsonObject);
} catch (Exception ex) {
ex.printStackTrace();
}
}
public static void getArray(Object object2) throws ParseException {
JSONArray jsonArr = (JSONArray) object2;
for (int k = 0; k < jsonArr.size(); k++) {
if (jsonArr.get(k) instanceof JSONObject) {
parseJson((JSONObject) jsonArr.get(k));
} else {
System.out.println(jsonArr.get(k));
}
}
}
public static void parseJson(JSONObject jsonObject) throws ParseException {
Set<Object> set = jsonObject.keySet();
Iterator<Object> iterator = set.iterator();
while (iterator.hasNext()) {
Object obj = iterator.next();
if (jsonObject.get(obj) instanceof JSONArray) {
System.out.println(obj.toString());
getArray(jsonObject.get(obj));
} else {
if (jsonObject.get(obj) instanceof JSONObject) {
parseJson((JSONObject) jsonObject.get(obj));
} else {
System.out.println(obj.toString() + "\t"
+ jsonObject.get(obj));
}
}
}
}}
The org.json library is easy to use.
Just remember (while casting or using methods like getJSONObject and getJSONArray) that in JSON notation
[ … ]represents an array, so library will parse it toJSONArray{ … }represents an object, so library will parse it toJSONObject
Example code below:
import org.json.*;
String jsonString = ... ; //assign your JSON String here
JSONObject obj = new JSONObject(jsonString);
String pageName = obj.getJSONObject("pageInfo").getString("pageName");
JSONArray arr = obj.getJSONArray("posts"); // notice that `"posts": [...]`
for (int i = 0; i < arr.length(); i++)
{
String post_id = arr.getJSONObject(i).getString("post_id");
......
}
You may find more examples from: Parse JSON in Java
Downloadable jar: http://mvnrepository.com/artifact/org.json/json
For the sake of the example lets assume you have a class Person with just a name.
private class Person {
public String name;
public Person(String name) {
this.name = name;
}
}
Jackson (Maven)
My personal favourite and probably the most widely used.
ObjectMapper mapper = new ObjectMapper();
// De-serialize to an object
Person user = mapper.readValue("{\"name\": \"John\"}", Person.class);
System.out.println(user.name); //John
// Read a single attribute
JsonNode nameNode = mapper.readTree("{\"name\": \"John\"}");
System.out.println(nameNode.get("name").asText());
Google GSON (Maven)
Gson g = new Gson();
// De-serialize to an object
Person person = g.fromJson("{\"name\": \"John\"}", Person.class);
System.out.println(person.name); //John
// Read a single attribute
JsonObject jsonObject = new JsonParser().parseString("{\"name\": \"John\"}").getAsJsonObject();
System.out.println(jsonObject.get("name").getAsString()); //John
Org.JSON (Maven)
This suggestion is listed here simply because it appears to be quite popular due to stackoverflow reference to it. I would not recommend using it as it is more a proof-of-concept project than an actual library.
JSONObject obj = new JSONObject("{\"name\": \"John\"}");
System.out.println(obj.getString("name")); //John
Use some kind of JSON parser.
GSON
https://github.com/google/gson
or Jackson
http://www.mkyong.com/java/how-to-convert-java-object-to-from-json-jackson/
I hope it will help you...!
use Jackson-
JSONArray objects=new JSONObject(jsondata).getJSONArray("objects");
for(int i=0;i<objects.length();i++){
JSONObject object=objects.getJSONObject(i);
System.out.println("value of left=="+object.getString("left"));
System.out.println("value of top=="+object.getString("top"));
}
I want to convert the following text file into a java object list, HashMaps seem not complext enough as the text file is Json
info = [{"key":"1",
"request":"ok",
"group": "user"},{...},...{}]