Writing to an object and reading from an object in Android.

Utilities.java

 public static void writeFile(Context context){
        teamMap = generateHashMap();
        try{
            FileOutputStream outputStream = context.openFileOutput(FILENAME, Context.MODE_PRIVATE);
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
            objectOutputStream.writeObject(teamMap);
            System.out.println(teamMap.size());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            Toast.makeText(context, "File not found.", Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            e.printStackTrace();
            Toast.makeText(context, "IO Exception.", Toast.LENGTH_SHORT).show();
        }

    }

    public static void readFile(Context context){

        teamMap = new HashMap<>();
        try{
            InputStream inputStream = context.openFileInput(FILENAME);
            if(inputStream != null){
                ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);
                HashMap<String, Integer> map = (HashMap<String, Integer>) objectInputStream.readObject();
                teamMap = map;
                System.out.println(map.size());
                System.out.println(teamMap.size());
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }