AdMob Interstitial Ad Implementation with counter

    //Variable Declaration
    private InterstitialAd interstitialAd;
    int counter = 1;

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    //Prepare for load Interstitial Ad on Fragment
    //call the function loadInterstitialAd() in the onCreate method
    private void loadInterstitialAd() {
        interstitialAd = new InterstitialAd(getActivity());
        interstitialAd.setAdUnitId(getResources().getString(R.string.admob_interstitial_unit_id));
        interstitialAd.loadAd(new AdRequest.Builder().build());
        interstitialAd.setAdListener(new AdListener() {
            @Override
            public void onAdClosed() {
                interstitialAd.loadAd(new AdRequest.Builder().build());
            }
        });
    }

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    //Display Interstitial Ad
    //call the function showInterstitialAd() in the onItemClickListener or other method
    private void showInterstitialAd() {
        if (interstitialAd != null && interstitialAd.isLoaded()) {
            if (counter == 3) {
                interstitialAd.show();
                counter = 1;
            } else {
                counter++;
            }
        }
    }