device speed in android GPS

package com.example.devicespeeddemo;

import java.math.BigDecimal;

import java.math.RoundingMode;

import android.app.Activity;

import android.app.AlertDialog;

import android.content.DialogInterface;

import android.content.DialogInterface.OnClickListener;

import android.location.Location;

import android.os.Bundle;

import android.text.Spannable;

import android.text.SpannableString;

import android.text.style.AbsoluteSizeSpan;

import android.view.LayoutInflater;

import android.view.Menu;

import android.view.MenuInflater;

import android.view.MenuItem;

import android.view.View;

import android.widget.TextView;

public class DeviceSpeedDemoActivity extends Activity implements GPSCallback{

    private GPSManager gpsManager = null;

    private double speed = 0.0;

    private int measurement_index = Constants.INDEX_KM;

    private AbsoluteSizeSpan sizeSpanLarge = null;

    private AbsoluteSizeSpan sizeSpanSmall = null;

@Override

public void onCreate(Bundle savedInstanceState)

{

    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

     

    gpsManager = new GPSManager();

     

    gpsManager.startListening(getApplicationContext());

    gpsManager.setGPSCallback(this);

     

    ((TextView)findViewById(R.id.info_message)).setText(getString(R.string.info));

     

    measurement_index = AppSettings.getMeasureUnit(this);

}

    @Override

    public void onGPSUpdate(Location location)

    {

            location.getLatitude();

            location.getLongitude();

            speed = location.getSpeed();

             

            String speedString = "" + roundDecimal(convertSpeed(speed),2);

            String unitString = measurementUnitString(measurement_index);

             

            setSpeedText(R.id.info_message,speedString + " " + unitString);

    }

    @Override

    protected void onDestroy() {

            gpsManager.stopListening();

            gpsManager.setGPSCallback(null);

             

            gpsManager = null;

             

            super.onDestroy();

    }

             

    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

            MenuInflater inflater = getMenuInflater();

        inflater.inflate(R.menu.menu, menu);

         

            return true;

    }

    @Override

    public boolean onOptionsItemSelected(MenuItem item) {

            boolean result = true;

     

            switch(item.getItemId())

            {

                    case R.id.menu_about:

                    {

                            displayAboutDialog();

                             

                            break;

                    }

                    case R.id.unit_km:

                    {

                            measurement_index = 0;

                             

                            AppSettings.setMeasureUnit(this, 0);

                             

                            break;

                    }

                    case R.id.unit_miles:

                    {

                            measurement_index = 1;

                             

                            AppSettings.setMeasureUnit(this, 1);

                             

                            break;

                    }

                    default:

                    {

                            result = super.onOptionsItemSelected(item);

                             

                            break;

                    }

            }

             

            return result;

    }

    private double convertSpeed(double speed){

            return ((speed * Constants.HOUR_MULTIPLIER) *
Constants.UNIT_MULTIPLIERS[measurement_index]);

    }

     

    private String measurementUnitString(int unitIndex){

            String string = "";

             

            switch(unitIndex)

            {

                    case Constants.INDEX_KM:                string = "km/h";        break;

                    case Constants.INDEX_MILES:     string = "mi/h";        break;

            }

             

            return string;

    }

     

    private double roundDecimal(double value, final int decimalPlace)

    {

            BigDecimal bd = new BigDecimal(value);

             

            bd = bd.setScale(decimalPlace, RoundingMode.HALF_UP);

            value = bd.doubleValue();

             

            return value;

    }

     

    private void setSpeedText(int textid,String text)

    {

            Spannable span = new SpannableString(text);

            int firstPos = text.indexOf(32);

             

            span.setSpan(sizeSpanLarge, 0, firstPos,Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

            span.setSpan(sizeSpanSmall, firstPos + 1,
text.length(),Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

             

            TextView tv = ((TextView)findViewById(textid));

             

            tv.setText(span);

    }

     

    private void displayAboutDialog()

    {

            final LayoutInflater inflator = LayoutInflater.from(this);

            final View settingsview = inflator.inflate(R.layout.about, null);

            final AlertDialog.Builder builder = new AlertDialog.Builder(this);

             

            builder.setTitle(getString(R.string.app_name));

            builder.setView(settingsview);

                             

            builder.setPositiveButton(android.R.string.ok, new OnClickListener() {

                    @Override

                    public void onClick(DialogInterface dialog, int which) {

                             

                    }

            });

                             

            builder.create().show();

    }

}