如何预载插页式广告-Android Studio

Question

用户进入主要活动后如何预加载插页式广告。在显示插页式广告之前，我该怎么做？

公共类Screen4扩展了AppCompatActivity实现的View.OnClickListener {

private Button button;
public View view;
private AdView mAdView;

Button play,pause;
MediaPlayer mediaPlayer;
int pausePosition;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_screen4);

    MobileAds.initialize(this, "ca-app-pub-7487211571427928~288076597");

    //   --- Admob ---
    view=getWindow().getDecorView().getRootView();

    Admob.createLoadBanner(getApplicationContext(), view);
    Admob.createLoadInterstitial(getApplicationContext(),null);
    //   --- *** ---


    mAdView = findViewById(R.id.adView);
    AdRequest adRequest = new AdRequest.Builder().build();
    mAdView.loadAd(adRequest);

    play=(Button)findViewById(R.id.play);
    pause=(Button)findViewById(R.id.pause);

    play.setOnClickListener(this);
    pause.setOnClickListener(this);

    button = (Button) findViewById(R.id.button5);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            openScreen5();
        }
    });


}

public void openScreen5() {
    Intent intent = new Intent(this, Screen5.class);
    startActivity(intent);
}

}

我希望该应用在显示插页广告之前预加载插页广告。