从Android内部存储读取JSON错误

Question

This is my code of saving json:

    public void saveCrimes (ArrayList<Crime> crimes) throws JSONException, FileNotFoundException, IOException {
            JSONArray jsonArray = new JSONArray();
            for (Crime c:crimes)
            {
                jsonArray.put(c.convertToJson());
            }
            Writer writer = null;
            OutputStream out = context.openFileOutput(fileName, Context.MODE_PRIVATE);
            writer = new OutputStreamWriter(out);
            writer.write(jsonArray.toString());
            writer.close();
            out.close();
        }
And this is my code of reading json :

public ArrayList<Crime> loadCrimes () throws IOException, JSONException {
        ArrayList<Crime> crimes = new ArrayList<Crime>();
        BufferedReader reader = null;
        StringBuilder builder = new StringBuilder();
        String line = null;
        try {
            InputStream in = context.openFileInput(fileName);
            reader = new BufferedReader(new InputStreamReader(in));
            while((line = reader.readLine()) != null)
                builder.append(line);
            JSONArray array = (JSONArray)new JSONTokener(builder.toString()).nextValue();
            for(int i = 0; i < array.length(); i++)
            {
                crimes.add(new Crime(array.getJSONObject(i)));
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        finally {
            if (reader != null)
                reader.close();
        }
        return crimes;
    }

The question is: code of saving json is correct, but when I run my application on my phone, create new crime, and restart the app, json stored before cannot be read. What makes me more confused is that when I run it on an emulator, it works well. Why?

Answer 1

I know what is wrong. Android Studio 2.0 cannot save the changes you have made in your codes if the change is very small. The solution is that building apk before running your application.