accelerometer code in class

Question

I'm writing an app that show accelerometer readings, I was able yesterday to write all the accelerometer code in the main activity and it works fine on emulator and my device.

But today I was trying to make a class that contains all the accelerometer code and return the three integers X,Y,Z in integer array only, so I make a code that I think it`s right but every time I run the project on the emulator and it always give me 0 ,0,0 . So I wish any help , please .

activity code ::

package com.example.accelerometer_sensor;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;

public class MainActivity extends Activity {

    int [] AccVal = new int[3];

    TextView acceleration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        AccelerometerClass acc = new AccelerometerClass();
        acc.AccelerometerInit(this);
         AccVal =acc.Vals;

         acceleration = (TextView)findViewById(R.id.acceleration);


         acceleration.setText("X: "+acc.Vals[0]+
                    "\nY: "+acc.Vals[1]+
                    "\nZ: "+acc.Vals[2]);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }


}

accelerometerClass :

package com.example.accelerometer_sensor;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

public class AccelerometerClass implements SensorEventListener 
{
    int [] Vals = new int[3];
    Sensor accelerometer;
    SensorManager sm;

    public void AccelerometerInit(Context context)
    {

        sm = (SensorManager)context.getSystemService(Context.SENSOR_SERVICE);       
        accelerometer=sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        sm.registerListener(this, accelerometer,SensorManager.SENSOR_DELAY_NORMAL); 
    }

    protected void onResume() {

        sm.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);

    }

    protected void onPause() {

        sm.unregisterListener(this);
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // TODO Auto-generated method stub

        Vals[0]=(int)event.values[0];
        Vals[1]=(int)event.values[1];
        Vals[2]=(int)event.values[2];
    }


}

please i stuck in this problem for along time , any help will be appreciate .

Answer 1

I suspect that the text is being written before the onSensorChanged event is being fired. So it goes like this...

1. Register listener
2. Write text (all 0s at this point)
3. Event fires and changes the x,y,z values

The text is already written though so the values aren't updating. I could be wrong but you could test this by stopping the thread for a few seconds before writing the values to the text field with a Thread.sleep(2000); 2000 is in milliseconds.

It could also be that the event isn't firing. You can check for this by adding a line inside the onSensorChanged() method that logs to your logcat.

Log.d(TAG, "onSensorChanged method has been invoked");

Edit: I just ran it. Everything works fine, but you're not getting the results you want because the text is being written before the event is firing. You need to update your UI when the onSensorChanged() method is called.

Answer 2

Implement getter method for object Vals in AccelerometerClass

public class AccelerometerClass implements SensorEventListener 
{
    int [] Vals = new int[3];
    Sensor accelerometer;
    SensorManager sm;
public AccelerometerClass(Context context)
{

    sm = (SensorManager)context.getSystemService(Context.SENSOR_SERVICE);       
    accelerometer=sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    sm.registerListener(this, accelerometer,SensorManager.SENSOR_DELAY_NORMAL); 
}

...

// getter method
public int getValue(int index) {
    return this.Vals[index];
}

}

Access it from MainActivity :

public class MainActivity extends Activity {

    int [] AccVal = new int[3];

    TextView acceleration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // this one will call constructor of AccelerometerClass and initialise sensors
        AccelerometerClass acc = new AccelerometerClass(getApplicationContext());



         acceleration = (TextView)findViewById(R.id.acceleration);

         // access like this here
         acceleration.setText("X: "+acc.getValue(0)+
                    "\nY: "+acc.getValue(1)+
                    "\nZ: "+acc.getValue(2));
    }
}

This will solve your problem