methods corresponding to the events in a rewarded video ad's lifecycle.

MainActivity.java

mRewardedVideoAd.setRewardedVideoAdListener(new RewardedVideoAdListener() {
            @Override
            public void onRewarded(RewardItem rewardItem) {
                Toast.makeText(getBaseContext(), "You get reward of : "+rewardItem.getAmount(), Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onRewardedVideoAdLoaded() {
                Toast.makeText(getBaseContext(), "Ad loaded.", Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onRewardedVideoAdOpened() {
                Toast.makeText(getBaseContext(), "Ad opened.", Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onRewardedVideoStarted() {
                Toast.makeText(getBaseContext(), "Ad started.", Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onRewardedVideoAdClosed() {
                Toast.makeText(getBaseContext(), "Ad closed.", Toast.LENGTH_SHORT).show();
                mRewardedVideoAd.loadAd(getString(R.string.ad_unit_id), new AdRequest.Builder().build());

            }

            @Override
            public void onRewardedVideoAdLeftApplication() {
                Toast.makeText(getBaseContext(), "Ad left application.", Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onRewardedVideoAdFailedToLoad(int i) {
                Toast.makeText(getBaseContext(), "Ad failed to load.", Toast.LENGTH_SHORT).show();
            }
        });