show ads that require activity context in service

Question

I want to show ads in a service. google admob works well because it needs context, but some other ad services like unity ads, adcolony, appodeal need activity context.

How can I provide activity context in a service. I think create an Activity will works but ads need some time to load the ad and then show so create a blank activity and show it.

For unity:

    UnityAds.initialize(this, "xxxxxxx", new IUnityAdsListener() {
      @Override
      public void onUnityAdsReady(String s) {
        Timber.e("onUnityAdsReady");
      }

      @Override
      public void onUnityAdsStart(String s) {
        Timber.e("onUnityAdsStart");
      }

      @Override
      public void onUnityAdsFinish(String s, UnityAds.FinishState finishState) {
        Timber.e("onUnityAdsFinish");
      }

      @Override
      public void onUnityAdsError(UnityAds.UnityAdsError unityAdsError, String s) {
        Timber.e("onUnityAdsError");
      }
    });

For adclony:

    AdColony.configure(this, "xxxx", "xxx");
    adColonyInterstitialListener = new AdColonyInterstitialListener() {
      @Override
      public void onRequestFilled(AdColonyInterstitial ad) {
        adColonyInterstitial = ad;
        /** Store and use this ad object to show your ad when appropriate */
      }
    };
    AdColony.requestInterstitial("xxx", adColonyInterstitialListener);

I want to show these ads from service how can I do it while they need activity context.