Android detect phone lifting action

Question

I want to perform some activity when the user lifts the phone from a flat surface. The method I am using right now is detect shake motion using phone's Accelerometer using the following code:

sensorMan = (SensorManager) getSystemService(SENSOR_SERVICE);
        accelerometer = sensorMan.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);

sensorMan.registerListener(this, accelerometer, SensorManager.SENSOR_STATUS_ACCURACY_HIGH);

public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
            mGravity = event.values.clone();
            // Shake detection
            float x = mGravity[0];
            float y = mGravity[1];
            float z = mGravity[2];

            mAccelLast = mAccelCurrent;
            mAccelCurrent = FloatMath.sqrt(x * x + y * y + z * z);
            float delta = mAccelCurrent - mAccelLast;
            mAccel = mAccel * 0.9f + delta;

            if (mAccel > 0.9) {
                //Perform certain tasks.
            }
        }

The issue I am facing with this code is the 0.9f threshold is reached sometimes even if the phone is still on the flat surface. I tried logging the mAccel value and found it to be rannging from 9.0 to 0.4 even when the phone is not even touched. Is there any guaranteed way to detect the phone's lift movement?

Answer 1

Solved the issue. All I wanted to do was to check for the "Y" value stated in the question and check if the value was greater than 1.0.

Note that, if the phone is kept in vertical position the Y is always around 9.8 but in such cases you can check for X instead. In my case user had to lift the phone and somewhen he will tilt the phone so I put a check for if(y >= 1.0 && y <= 2.0);

EDIT : UPDATED CODE

    @Override
public void onSensorChanged(SensorEvent event) {
    try {
        if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
            mGravity = event.values.clone();
            // Shake detection
            float x = mGravity[0];
            float y = mGravity[1];
            float z = mGravity[2];

            float yAbs = Math.abs(mGravity[1]);

            mAccelLast = mAccelCurrent;
            mAccelCurrent = FloatMath.sqrt(x * x + y * y + z * z);
            float delta = mAccelCurrent - mAccelLast;
            mAccel = mAccel * 0.9f + delta;

            if (yAbs > 2.0 && yAbs < 4.0 && !isAlerted() && !isCallActive()) {
                alert();
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}