java - json file not being read

Question

I have an app that is supposed to read a json file and inset its contents into a list view, I know this question was asked tons of times here but I can't understand why it's not working. I managed to narrow my problem to 1 line so far, JSONObject object = new JSONObject(readJSON());. This is all of my code:

public class MainActivity extends AppCompatActivity {
    ListView listView;
    ArrayList<Post> arrayList;
    private static final String TAG = "MyActivity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = (ListView) findViewById(R.id.lvPosts);
        arrayList = new ArrayList<>();

        try {
            JSONObject object = new JSONObject(readJSON());
            JSONArray array = object.getJSONArray("data");
            for (int i = 0; i < array.length(); i++) {

                JSONObject jsonObject = array.getJSONObject(i);
                String productName = jsonObject.getString("productName");
                String locationName = jsonObject.getString("locationName");
                String price = jsonObject.getString("price");
                String date = jsonObject.getString("date");
                String description = jsonObject.getString("description");
                String comment = jsonObject.getString("comment");
                Log.i(TAG, price);
                Post post = new Post();
                post.setItemName(productName);
                post.setLocationName(locationName);
                post.setPrice(price);
                post.setDate(date);
                post.setDescription(description);
                post.setExistingComment(comment);
                arrayList.add(post);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        PostAdapter adapter = new PostAdapter(this, arrayList);
        listView.setAdapter(adapter);
    }

    public String readJSON() {
        String json = null;
        try {
            // Opening data.json file
            InputStream inputStream = getAssets().open("MOCK_DATA.json");
            int size = inputStream.available();
            byte[] buffer = new byte[size];
            // read values in the byte array
            inputStream.read(buffer);
            inputStream.close();
            // convert byte to string
            json = new String(buffer, "UTF-8");
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        return json;
    }
}

My problem is that once I run the app my listView will remain empty and wont be populated with data.

Answer 1

if you are using java version >jdk1.7 then I would recommend you use Files class from "java.nio.file" package . you can easily read JSON file in a single line code.

 public String readJSON() {
    String jsontext="";
 try{
 jsontext= new String(Files.readAllBytes(Paths.get("<file path>"),StandardCharset.UTF_8);
 }
catch(Exception ex){
ex.printStackTrace();
}
return jsontext;
}

after that you can use JSONObject to parse string like below:---

JSONObject object = new JSONObject(readJSON());