Reading application's versionCode and versionName

When versioning your application, you use the AndroidManifest.xml to specify the versionCode and versionName.

You can read your application’s versionCode and versionName from you activity using the following code:

PackageInfo packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
int versionNumber = packageInfo.versionCode;
String versionName = packageInfo.versionName;

To know more about versioning your app read de documentation.