AdMob Interstitial Ad Implementation

//Variable Declaration
private InterstitialAd interstitialAd;

//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_id));
        interstitialAd.loadAd(new AdRequest.Builder().build());
        interstitialAd.setAdListener(new AdListener() {
            @Override
            public void onAdClosed() {
                //your method here when the ad is closed
                interstitialAd.loadAd(new AdRequest.Builder().build());
            }
        });
    }

//Prepare for load Interstitial Ad on Activity
//call the function loadInterstitialAd() in the onCreate method
private void loadInterstitialAd() {
        interstitialAd = new InterstitialAd(getApplicationContext());
        interstitialAd.setAdUnitId(getResources().getString(R.string.admob_interstitial_id));
        interstitialAd.loadAd(new AdRequest.Builder().build());
        interstitialAd.setAdListener(new AdListener() {
            @Override
            public void onAdClosed() {
                //your method here when the ad is closed
                interstitialAd.loadAd(new AdRequest.Builder().build());
            }
        });
    }

//Display Interstitial Ad
//call the function showInterstitialAd() in the onItemClickListener or other method
private void showInterstitialAd() {
        if (interstitialAd.isLoaded()) {
            interstitialAd.show();
        }
    }