Get Application version number from AndroidManifest.xml

  public static String getAppVersionName(Context mContext, Class cls) {

    try {

      ComponentName comp = new ComponentName(mContext, cls);

      PackageInfo pinfo = mContext.getPackageManager().getPackageInfo(comp.getPackageName(), 0);

      return "Version: " + pinfo.versionName;

    } catch (Exception e) {

      return null;

    }

  }