How i save data from android game to a local json file

i want to save the user's data in json file in a internel memory but it doesn't work what's the problem ???? this is the code ...................................................................................................................

public JSONObject addToJson(Context context, String email,String password)throws Exception{
    String id_P = UUID.randomUUID().toString();
    JSONObject jsonObject = new JSONObject();

    jsonObject.put("id_P",id_P);
    jsonObject.put("Email",email);
    jsonObject.put("password",password);

    
    String j = jsonObject.toString();
    System.out.println(j);
    File file = new File(context.getFilesDir(),"dbApp.json");
    FileWriter fileWriter = new FileWriter(file);
    BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
    bufferedWriter.write(j);
    bufferedWriter.close();

    return jsonObject;
}

You can use different of local database like Room, Realm etc. But for

Writing:  you need to convert your JSON into String or Model class and then you can store into Database. 
Reading  : convert string into JSON or Model Class and use the same.

Take more look at
https://realm.io/docs/java/latest/

Example of Realm Database in Android You can option of choose this :

Writing

User user = realm.createObject(User.class); // Create a new object
user.setName("John");
user.setEmail("john@corporation.com");
realm.commitTransaction();

Reading

RealmQuery<User> query = realm.where(User.class);

// Add query conditions:
query.equalTo("name", "John");
query.or().equalTo("name", "Peter");

// Execute the query:
RealmResults<User> result1 = query.findAll();

// Or alternatively do the same all at once (the "Fluent interface"):
RealmResults<User> result2 = realm.where(User.class)
                              .equalTo("name", "John")
                              .or()
                              .equalTo("name", "Peter")
                              .findAll();

well I am not an expert in this matter but I think here is what you should do:

first add this JSON converter library to your build.gradle:

implementation 'com.google.code.gson:gson:2.8.6'

after that you need to create a model class in which you should categorize your data in different maps , NOTE: use maps all the time array list won't work properly:

Class Model{
Map<String ,String> userData;

 public Model(Map<String, String> setUserdata) {
    this.setUserdata = setUserdata;
}


         public void setSetUserdata(Map<String, String> setUserdata) {
          this.setUserdata = setUserdata;
          }


}  

okay , and then for setting data you should create a Map and then initialize the class and pass it the Map similar to this:

Map<String ,String> userData=new HashMap<>();
        setUserdata.put("username","something");
        setUserdata.put("password","something");
Model model=new Model(userData);

and now you can easily convert this to a JSON :
Gson gson = new Gson();
String json = gson.toJson(model);

and you can easily save this in file with text format.