Android Example Sensor Application

In this example data from the accelerometer is written to a TextView (Android TextArea), this example could easily be altered to use anyone of the other sensors (temperature, light, pressure, etc).

package hejp.AccelerometerExample;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;
import android.hardware.SensorManager;
import android.hardware.SensorEventListener;
import android.hardware.SensorEvent;
import android.hardware.Sensor;
import java.util.List;

public class AccelerometerExample extends Activity {
	SensorManager sm = null;
	TextView accText = null;
	List list;

	/* This responds to sensor events */
	SensorEventListener sel = new SensorEventListener(){
		public void onAccuracyChanged(Sensor sensor, int accuracy) {
			/* Isn't required for this example */

		}
		public void onSensorChanged(SensorEvent event) {
			/* Write the accelerometer values to the TextView */
			float[] values = event.values;
			accText.setText("x: "+values[0]+"\ny: "+values[1]+"\nz: "+values[2]);
		}

	};

    /* Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        /* Get a SensorManager instance */
        sm = (SensorManager)getSystemService(SENSOR_SERVICE);

        /* This corresponds to a TextView element in main.xml with android:id="@+id/accText" */
        accText = (TextView)findViewById(R.id.accText);

        /* Get list of accelerometers */
        list = sm.getSensorList(Sensor.TYPE_ACCELEROMETER);

        /* If there are any accelerometers register a listener to the first else
           print a little error message */
        if(list.size()>0){
        	sm.registerListener(sel, list.get(0), SensorManager.SENSOR_DELAY_NORMAL);
        }else{
        	Toast.makeText(getBaseContext(), "Error: No Accelerometer.", Toast.LENGTH_LONG);
        }
    }

	@Override
	protected void onStop() {
		/* Always a good idea to unregister, disconnect, close, etc things */
		if(list.size()>0){
			/* This actually unregisters a listener for all sensors, but it can be done
			   on a sensor by sensor basis */
			sm.unregisterListener(sel);
		}
		super.onStop();
	}

}

Personally I think that Android is the most interesting and significant mobile platform ever. The fact that it’s open and it’s level of functionality, not to mention it’s backed by Google, make it like nothing else.

Having had written mobile applications (in Java) before and enduring the seemingly endless interoperability problems and senseless security restrictions (for example bluetooth PSM restrictions making to impossible to connect to a wiimote) makes this a real excitement.