Create class from json with Gson

Question

I am using:

Gson gson = new Gson();
return gson.fromJson(jsonstr,cls);

Where jsonstr is:

{"title": "ttl","data": "dta"}

And cls is:

public class GSONTest {

public String title;
public String data;

public String getTitle() {
    return title;
}

public String getData() {
    return data;
}

}

But I with do to something more complicated, here is example of my json:

{
  "Some1": {
    "data": "dta",
    "title": "ttl"
  },
  "Some3": {
    "data": "dta2",
    "title": "ttl2"
  }
}

How should my class look like for this type of json?

Possible duplicate of [Generate Java class from JSON?](http://stackoverflow.com/questions/1957406/generate-java-class-from-json) — Nithinlal, Dec 05 '16 at 11:06

score 0 · Answer 1 · answered Dec 05 '16 at 11:04

0

    Type type = new TypeToken<Map<String, GSONTest>>(){}.getType();
    Map<String, GSONTest> gsonTestMap = gson.fromJson(jsonstr, type);

answered Dec 05 '16 at 11:04

John O'Reilly

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score 0 · Answer 2 · answered Dec 05 '16 at 11:27

As you can see every JSON Object is like a class in java so you should create a Java class for the root of your JSON something like this:

public class GSONTest {

    GSONTest2 element1;
    GSONTest2 element2;

    //constructor, getters and setters here

}

You see that I used another object so it can stored the "level2" of your JSON this class will be something like this:

public class GSONTest2{
    String element1; //This will stored "dta and dta2"
    String element2; //This will stored "ttl1 and ttl2"
    //constructor, getters and setters here

}

So when you are calling GSON you should just do:

Gson gson = new Gson();
return gson.fromJson(jsonstr,GSONTest.class);

Syed Raza Mehdi · Accepted Answer · 2016-12-05T11:23:08.407

-1

Example {

 @SerializedName("Some1")
 @Expose
 private Some1 some1;
 @SerializedName("Some3")
 @Expose
 private Some3 some3;


 public Some1 getSome1() {
  return some1;
 }

 public void setSome1(Some1 some1) {
  this.some1 = some1;
 }


 public Some3 getSome3() {
  return some3;
 }


 public void setSome3(Some3 some3) {
  this.some3 = some3;
 }

}

-----------------------------------com.example.Some1.java----------------

 import com.google.gson.annotations.Expose;
 import com.google.gson.annotations.SerializedName;

 public class Some1 {

  @SerializedName("data")
  @Expose
  private String data;
  @SerializedName("title")
  @Expose
  private String title;

 public String getData() {
   return data;
 }


 public void setData(String data) {
  this.data = data;
 }


 public String getTitle() {
   return title;
 }


 public void setTitle(String title) {
   this.title = title;
 }

}

-----------------------------------com.example.Some3.java----------------

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class Some3 {

@SerializedName("data")
@Expose
private String data;
@SerializedName("title")
@Expose
private String title; 

public String getData() {
return data;
}


public void setData(String data) {
 this.data = data;
}


public String getTitle() {
 return title;
}


public void setTitle(String title) {
 this.title = title;
}

}

This is activity code for you, ENJOY!!!

 public class MainActivity extends AppCompatActivity {

 String json = "{\n" +
        "  \"Some1\": {\n" +
        "    \"data\": \"dta\",\n" +
        "    \"title\": \"ttl\"\n" +
        "  },\n" +
        "  \"Some3\": {\n" +
        "    \"data\": \"dta2\",\n" +
        "    \"title\": \"ttl2\"\n" +
        "  }\n" +
        "}";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Example mExample = new Gson().fromJson(json, Example.class);

    Toast.makeText(this, mExample.toString(), Toast.LENGTH_SHORT).show();
}
}

You can also use this website to generate class link

edited Dec 05 '16 at 11:23

answered Dec 05 '16 at 10:57

Syed Raza Mehdi

4,067
1
31
47

don't down vote if you don't know the answer yourself, this is workable solution. – Syed Raza Mehdi Dec 05 '16 at 11:00
1

no, it is not. The OP has already the pojo to parse the inner json. – Blackbelt Dec 05 '16 at 11:03
it is so see my edited answer before thought class for this {"title": "ttl","data": "dta"} json is needed post the JAVA code too for further guidance. – Syed Raza Mehdi Dec 05 '16 at 11:07
1

it is still wrong, Op has a json with variable keys name. – Blackbelt Dec 05 '16 at 11:08
share me the code the one you are using to parse it with GSON don't miss to use @SerializedName notation. – Syed Raza Mehdi Dec 05 '16 at 11:09
I have shared the activity code as well and this is working in the sample project I made on my PC. – Syed Raza Mehdi Dec 05 '16 at 11:21
2

what if have 1000 entries named `Some0...Some1000`? Would you create 1000 different pojos ? – Blackbelt Dec 05 '16 at 11:22
yes in that case use json array this json structure is not preferable to use, make a json object for SomeOne and in that you must have array of object, first object represent SomeOne1 and so on so forth good luck and accept the answer please one you test it your self. – Syed Raza Mehdi Dec 05 '16 at 11:26
who is down voting this question please see the attached screen shot as a proof it is working. Do not mess the stackover flow like this be professional. – Syed Raza Mehdi Dec 05 '16 at 12:46

score -1 · Answer 4 · answered Dec 05 '16 at 11:00

Your class is like this

package com.example;

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class Example {

@SerializedName("Some1")
@Expose
private Some1 some1;
@SerializedName("Some3")
@Expose
private Some3 some3;


public Some1 getSome1() {
return some1;
}

public void setSome1(Some1 some1) {
this.some1 = some1;
}

public Some3 getSome3() {
return some3;
}

public void setSome3(Some3 some3) {
this.some3 = some3;
}}

Next Some1.class

package com.example;

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class Some1 {

@SerializedName("data")
@Expose
private String data;
@SerializedName("title")
@Expose
private String title;


public String getData() {
return data;
}

public void setData(String data) {
this.data = data;
}


public String getTitle() {
return title;
}


public void setTitle(String title) {
this.title = title;
}

}

next Some3.class

package com.example;

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

public class Some3 {

@SerializedName("data")
@Expose
private String data;
@SerializedName("title")
@Expose
private String title;

/**
* 
* @return
* The data
*/
public String getData() {
return data;
}

/**
* 
* @param data
* The data
*/
public void setData(String data) {
this.data = data;
}

/**
* 
* @return
* The title
*/
public String getTitle() {
return title;
}

/**
* 
* @param title
* The title
*/
public void setTitle(String title) {
this.title = title;
}

}

Create class from json with Gson

4 Answers4