PackageManager packageManager = getPackageManager();
        try {
            PackageInfo packageInfo = packageManager.getPackageInfo(getPackageName(), 0);
            Log.d("version", packageInfo.versionName);//獲取版本 name
            Log.d("version", packageInfo.getLongVersionCode()+"");//獲取版本 Code
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }

getPackageName() 不僅僅只能寫本app, 也可以寫第三方app的包名, 以此獲取其他app的版本號！