How to check if Location Services are enabled?

I'm developing an app on Android OS. I don't know how to check if Location Services are enabled or not.

I need a method that returns "true" if they are enabled and "false" if not (so in the last case I can show a dialog to enable them).

You can use the below code to check whether gps provider and network providers are enabled or not.

LocationManager lm = (LocationManager)context.getSystemService(Context.LOCATION_SERVICE);
boolean gps_enabled = false;
boolean network_enabled = false;

try {
    gps_enabled = lm.isProviderEnabled(LocationManager.GPS_PROVIDER);
} catch(Exception ex) {}

try {
    network_enabled = lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
} catch(Exception ex) {}

if(!gps_enabled && !network_enabled) {
    // notify user
    new AlertDialog.Builder(context)
        .setMessage(R.string.gps_network_not_enabled)
        .setPositiveButton(R.string.open_location_settings, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface paramDialogInterface, int paramInt) {
                context.startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
            }
        })
        .setNegativeButton(R.string.Cancel,null)
        .show();    
}

And in the manifest file, you will need to add the following permissions

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>