PackageInfo pinfo;
try {
    pinfo = getPackageManager().getPackageInfo(getPackageName(), 0);
} catch (NameNotFoundException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
    pinfo = null;
}

appVersion = pinfo.versionCode;

public class NonActivityClass implements SensorListener{
Context mContext;
public NonActivtiyClass(Context context) {
this.mContext = context;
}
//Rest of your code
}

NonActivityClass nac = new NonActivityClass(this);

public int getAppVersionCode() {
    return BuildConfig.VERSION_CODE;
}