Writer not working for json file using Gson ,json file is blank after code execution

Question

I'm trying to write json data to a json file.

After code execution no errors are thrown but the .json file is empty.

Please find below code and help on this

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;

public class Test {
    public static void main(String[] args) throws JSONException {
        try {
            List<String> foo = new ArrayList<String>();
            foo.add("1");
            foo.add("2");
            foo.add("3");
            System.out.println("values :: "+foo);

            Writer writer = new FileWriter("operatorList.json");
            Gson gson = new GsonBuilder().create();
            gson.toJson(foo, writer);
        }
        catch(Exception e) {
            e.printStackTrace();            
        }
    }   
}

Answer 1

You are in the right way, just flush() and close() the writer, like this:

import java.io.BufferedWriter;

import java.io.FileWriter;

import java.io.IOException;

import java.io.Writer;

import java.util.ArrayList;

import java.util.List;

import com.google.gson.Gson;

import com.google.gson.GsonBuilder;

import com.google.gson.JsonObject;

public class Test {

public static void main(String[] args) throws JSONException {    
    try{
        List<String> foo = new ArrayList<String>();
        foo.add("1");
        foo.add("2");
        foo.add("3");
        System.out.println("values :: "+foo);
        Writer writer = new FileWriter("operatorList.json");
        Gson gson = new GsonBuilder().create();
        gson.toJson(foo, writer);
        writer.flush(); //flush data to file   <---
        writer.close(); //close write          <---
    }catch(Exception e){
        e.printStackTrace();
    }    
}