org.json.JSONArray may be what you want.
String message;
JSONObject json = new JSONObject();
json.put("name", "student");
JSONArray array = new JSONArray();
JSONObject item = new JSONObject();
item.put("information", "test");
item.put("id", 3);
item.put("name", "course1");
array.put(item);
json.put("course", array);
message = json.toString();
// message
// {"course":[{"id":3,"information":"test","name":"course1"}],"name":"student"}
Answer from srain on Stack OverflowVideos
org.json.JSONArray may be what you want.
String message;
JSONObject json = new JSONObject();
json.put("name", "student");
JSONArray array = new JSONArray();
JSONObject item = new JSONObject();
item.put("information", "test");
item.put("id", 3);
item.put("name", "course1");
array.put(item);
json.put("course", array);
message = json.toString();
// message
// {"course":[{"id":3,"information":"test","name":"course1"}],"name":"student"}
In contrast to what the accepted answer proposes, the documentation says that for JSONArray() you must use put(value) no add(value).
https://developer.android.com/reference/org/json/JSONArray.html#put(java.lang.Object)
(Android API 19-27. Kotlin 1.2.50)
I looked at Google's Gson as a potential JSON plugin. Can anyone offer some form of guidance as to how I can generate Java from this JSON string?
Google Gson supports generics and nested beans. The [] in JSON represents an array and should map to a Java collection such as List or just a plain Java array. The {} in JSON represents an object and should map to a Java Map or just some JavaBean class.
You have a JSON object with several properties of which the groups property represents an array of nested objects of the very same type. This can be parsed with Gson the following way:
package com.stackoverflow.q1688099;
import java.util.List;
import com.google.gson.Gson;
public class Test {
public static void main(String... args) throws Exception {
String json =
"{"
+ "'title': 'Computing and Information systems',"
+ "'id' : 1,"
+ "'children' : 'true',"
+ "'groups' : [{"
+ "'title' : 'Level one CIS',"
+ "'id' : 2,"
+ "'children' : 'true',"
+ "'groups' : [{"
+ "'title' : 'Intro To Computing and Internet',"
+ "'id' : 3,"
+ "'children': 'false',"
+ "'groups':[]"
+ "}]"
+ "}]"
+ "}";
// Now do the magic.
Data data = new Gson().fromJson(json, Data.class);
// Show it.
System.out.println(data);
}
}
class Data {
private String title;
private Long id;
private Boolean children;
private List<Data> groups;
public String getTitle() { return title; }
public Long getId() { return id; }
public Boolean getChildren() { return children; }
public List<Data> getGroups() { return groups; }
public void setTitle(String title) { this.title = title; }
public void setId(Long id) { this.id = id; }
public void setChildren(Boolean children) { this.children = children; }
public void setGroups(List<Data> groups) { this.groups = groups; }
public String toString() {
return String.format("title:%s,id:%d,children:%s,groups:%s", title, id, children, groups);
}
}
Fairly simple, isn't it? Just have a suitable JavaBean and call Gson#fromJson().
See also:
- Json.org - Introduction to JSON
- Gson User Guide - Introduction to Gson
Bewaaaaare of Gson! It's very cool, very great, but the second you want to do anything other than simple objects, you could easily need to start building your own serializers (which isn't that hard).
Also, if you have an array of Objects, and you deserialize some json into that array of Objects, the true types are LOST! The full objects won't even be copied! Use XStream.. Which, if using the jsondriver and setting the proper settings, will encode ugly types into the actual json, so that you don't loose anything. A small price to pay (ugly json) for true serialization.
Note that Jackson fixes these issues, and is faster than GSON.
Google GSON does this; I've used it on several projects and it's simple and works well. It can do the translation for simple objects with no intervention, but there's a mechanism for customizing the translation (in both directions,) as well.
Gson g = ...;
String jsonString = g.toJson(new Customer());
You can use Gson for that:
Maven dependency:
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.0</version>
</dependency>
Java code:
Customer customer = new Customer();
Product product = new Product();
// Set your values ...
Gson gson = new Gson();
String json = gson.toJson(customer);
Customer deserialized = gson.fromJson(json, Customer.class);