How to improve the performance of the BufferedWriter in Android?

Question

I am developing in Android , and I try to record the Sensor value of Android phone into .csv file via BufferedWriter.

The code is like the following:

//recordData
private float ACCELEROMETER_Gx = 0 , ACCELEROMETER_Gy = 0 , ACCELEROMETER_Gz = 0;
private float GRAVITY_X = 0 , GRAVITY_Y = 0 , GRAVITY_Z = 0;
private float GYROSCOPE_X = 0 , GYROSCOPE_Y = 0 , GYROSCOPE_Z = 0;
private float ACCELERATION_X = 0 , ACCELERATION_Y = 0 , ACCELERATION_Z = 0;
private float MAGNETIC_FIELD_X = 0 , MAGNETIC_FIELD_Y = 0 , MAGNETIC_FIELD_Z = 0;
private float PRESSURE = 0;
private float ROTATION_VECTOR_X = 0 , ROTATION_VECTOR_Y = 0 , ROTATION_VECTOR_Z = 0;

When the Sensor has change , it will write into .csv file.

    @Override
        public void onSensorChanged(SensorEvent event) {
            if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {

                ACCELEROMETER_Gx = event.values[0];
                ACCELEROMETER_Gy = event.values[1];
                ACCELEROMETER_Gz = event.values[2];

            }else if (event.sensor.getType() == Sensor.TYPE_GRAVITY) {
                GRAVITY_X = event.values[0];
                GRAVITY_Y = event.values[1];
                GRAVITY_Z = event.values[2];


            }else if (event.sensor.getType() == Sensor.TYPE_GYROSCOPE) {
                GYROSCOPE_X = event.values[0];
                GYROSCOPE_Y = event.values[1];
                GYROSCOPE_Z = event.values[2];


            }else if (event.sensor.getType() == Sensor.TYPE_LINEAR_ACCELERATION) {
                ACCELERATION_X = event.values[0];
                ACCELERATION_Y = event.values[1];
                ACCELERATION_Z = event.values[2];


            }else if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {

                MAGNETIC_FIELD_X = event.values[0];
                MAGNETIC_FIELD_Y = event.values[1];
                MAGNETIC_FIELD_Z = event.values[2];

            }else if (event.sensor.getType() == Sensor.TYPE_PRESSURE) {
                PRESSURE = event.values[0];

            }else if (event.sensor.getType() == Sensor.TYPE_ROTATION_VECTOR) {

                ROTATION_VECTOR_X = event.values[0];
                ROTATION_VECTOR_Y = event.values[1];
                ROTATION_VECTOR_Z = event.values[2];
            }


            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss.SSS");
            String SensorChangeTime = sdf.format(new Date(System.currentTimeMillis()));

            String SensorValue =
                    SensorChangeTime + "," +
                    appendcomma(ACCELEROMETER_Gx) + appendcomma(ACCELEROMETER_Gy) + appendcomma(ACCELEROMETER_Gz) +
                    appendcomma(GRAVITY_X) + appendcomma(GRAVITY_Y) + appendcomma(GRAVITY_Z) +
                    appendcomma(GYROSCOPE_X) + appendcomma(GYROSCOPE_Y) + appendcomma(GYROSCOPE_Z) +
                    appendcomma(ACCELERATION_X) + appendcomma(ACCELERATION_Y) + appendcomma(ACCELERATION_Z) +
                    appendcomma(MAGNETIC_FIELD_X) + appendcomma(MAGNETIC_FIELD_Y) + appendcomma(MAGNETIC_FIELD_Z) +
                    appendcomma(PRESSURE) +
                    appendcomma(ROTATION_VECTOR_X) + appendcomma(ROTATION_VECTOR_Y) + appendcomma(ROTATION_VECTOR_Z) + '\n';

            writeData(SensorValue);
        }

        private String appendcomma(float value){
            return String.valueOf(value) + ",";
        }

        private void writeData(String Data){
            try {

                fw = new FileWriter(path+"/" + FileRecordName, true);
                BufferedWriter bw = new BufferedWriter(fw);
                bw.write(Data);
                bw.close();

            }catch (IOException e){
                Log.d(TAG,"writeData---e = " + e.toString());
            }
        }

When the sensor value change , it will write to the .csv file via following code every time:

            fw = new FileWriter(path+"/" + FileRecordName, true);
            BufferedWriter bw = new BufferedWriter(fw);
            bw.write(Data);
            bw.close();

Is it correct or not for creating the new FileWriter and the coles every time?

How to improve the performance of the BufferedWriter in Android ?

Check [this](https://stackoverflow.com/questions/1062113/fastest-way-to-write-huge-data-in-text-file-java). It explains well. — Kruti Parekh, May 04 '18 at 04:52

score 0 · Answer 1 · answered May 04 '18 at 04:29

Yes, that is a correct behavior, for every write operation you have to create a new FileWriter and close it. However since API 19 you can do it with try-with-resources for simplicity:

try (BufferedWriter bw = new BufferedWriter(new FileWriter(FILENAME))) {

    bw.write(data);

    // no need to close it.
    //bw.close();

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

How to improve the performance of the BufferedWriter in Android?

1 Answers1