In the below example I have described how to get data from assets folder. Firstly I have created txt.json file in assets folder. In txt.json file I have added JSON data. Now See In MainActivity code I have created loadJSONFromAsset() method, in this method getAssets()method returns an AssetManager instance.

Step(1)- Created a txt.json file in assets folder and added below JSON data in txt.json file-
 

{
  "domain":"Java",
  "employee": {
    "name":       "sachin",
    "salary":      76000,
    "married":    true
  }
}

Step(2)MainActivity-

public class MainActivity extends ActionBarActivity {
    TextView text1, text2,text3,text4;
    String json = null;
    public static final String JSON_STRING = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        text1 = (TextView) findViewById(R.id.domain);

        text2 = (TextView) findViewById(R.id.emp_name);
        text3 =(TextView)findViewById(R.id.salary);
        text4=(TextView)findViewById(R.id.married);

        String json = loadJSONFromAsset();

        JSONObject jsonObject = null;
        try {
            jsonObject = new JSONObject(json);


            text1.setText(jsonObject.getString("domain"));


              //employee description
            JSONObject empObject = jsonObject.getJSONObject("employee");

            //employee name
            text2.setText(empObject.getString("name"));
            //employee salary
            text3.setText(empObject.getString("salary"));
            //employee married status
            text4.setText(empObject.getString("married"));

        } catch (JSONException e) {
            e.printStackTrace();
        }

    }

    public String loadJSONFromAsset() {
        try {
            InputStream is = getAssets().open("txt.json");

            int size =is.available();
            // Read the entire asset into a local byte buffer.
            byte[]buffer= new byte[size];

            is.read(buffer);
            is.close();
            json=new String(buffer,"UTF-8");

        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        return json;
    }


    }