Convert object to JSON in Android

Question

Is there a simple method to convert any object to JSON in Android?

Solution 1

Most people are using gson : check this

Gson gson = new Gson();
String json = gson.toJson(myObj);

Solution 2

public class Producto {

int idProducto;
String nombre;
Double precio;



public Producto(int idProducto, String nombre, Double precio) {

    this.idProducto = idProducto;
    this.nombre = nombre;
    this.precio = precio;

}
public int getIdProducto() {
    return idProducto;
}
public void setIdProducto(int idProducto) {
    this.idProducto = idProducto;
}
public String getNombre() {
    return nombre;
}
public void setNombre(String nombre) {
    this.nombre = nombre;
}
public Double getPrecio() {
    return precio;
}
public void setPrecio(Double precio) {
    this.precio = precio;
}

public String toJSON(){

    JSONObject jsonObject= new JSONObject();
    try {
        jsonObject.put("id", getIdProducto());
        jsonObject.put("nombre", getNombre());
        jsonObject.put("precio", getPrecio());

        return jsonObject.toString();
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        return "";
    }

}

Solution 3

Might be better choice:

@Override
public String toString() {
    return new GsonBuilder().create().toJson(this, Producto.class);
}

Solution 4

download the library Gradle:

implementation 'com.google.code.gson:gson:2.9.0'

To use the library in a method.

Gson gson = new Gson();

//transform a java object to json
System.out.println("json =" + gson.toJson(Object.class).toString());

//Transform a json to java object
String json = string_json;
List<Object> lstObject = gson.fromJson(json_ string, Object.class);

Solution 5

Spring for Android do this using RestTemplate easily:

final String url = "http://192.168.1.50:9000/greeting";
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
Greeting greeting = restTemplate.getForObject(url, Greeting.class);

View more solutions

Comments

[Klaus Groenbaek]

You don't need to add MappingJackson2HttpMessageConverter to RestTemplate, if the Jackson Jar is in the classpath it is added automatically.

[Neria Nachum]

Why is this a better choice?

[Thizzer]

Wanting to be able to convert an object to a JSON string does not necessarily mean you want the object's string representation to always be JSON.

[Hesam]

@NeriaNachum, The thing was in my mind when I answered having a class with a lot of attributes. Overriding its toString() method creates many String objects when you print in default way - generated by Android Studio or IntelliJ Idea - however, this is one line of code and using power of GsonBuilder.

[Hesam]

@Thizzer, You are absolutely right. I was thinking it is good to be shared and seen by developers (those who aren't familiar with approach at least). Then they will use whenever they need.

[adnaan.zohran]

I too feel this as better choice as the conversion can be handled from the model itself, abstracting out the implementation.

[M at]

Why we have no embedded method for toJson? But we have for fromJson ?

[Bhimbim]

i prefer this way, each object has their own stringify method, thank you for the insight !.

[Matthew Read]

This is the opposite of what was asked.

[gumuruh]

try to use gson they have it.

[Frank Gue]

But it is very complicated if you want to offuscate your code