To detect a fall

Question

I am developing an app which accesses accelerometer in order to detect a fall by measuring the values of acceleration in x,y and z directions. Below is my code, I have applied algorithm which uses two threshold values(min and max) rest of the algo you can see in the code itself. The problem i am facing is that the app is not displaying toast i have done some mild experiments with my friend's phone. After dropping my phone from a certain height(approximately 30 cm.) and catching it. But no toast appear on the screen.I am unable to identify whether there is a problem in my ALGO or TOAST. I don't know what to do next please help.

@Override
public void onSensorChanged(SensorEvent event) {
    if (started) {
        double x = event.values[0];
        double y = event.values[1];
        double z = event.values[2];
        long timestamp = System.currentTimeMillis();
        Data data = new Data(timestamp, x, y, z);
        sensorData.add(data);
    }

    if(event.sensor.getType()==Sensor.TYPE_ACCELEROMETER){
        double gacc=SensorManager.STANDARD_GRAVITY;
        double a=event.values[0];
        double b=event.values[1];
        double c=event.values[2];
        long mintime=System.currentTimeMillis();
        boolean min = false;
        boolean max = false;
        int m = 0;
        double xyz=Math.round(Math.sqrt(Math.pow(a,2)+Math.pow(b,2)+Math.pow(c,2)));

        if(xyz<=3.0){
            min = true;
        }
        if(min==true){
            m++;
            if(xyz>=14){
                max=true;
            }
        }
        if(min && max==true){
            Toast.makeText(MainActivity.this,"FALL DETECTED!",Toast.LENGTH_LONG).show();
            m=0;
            min=false;
            max=false;
        }
        if (m>4) {
            m=0;
            min=false;
            max=false;
        }
    }
}