如何在没有onCreate方法的其他类中添加Interstitial AdMob out MainActivity？

// AdManager.java

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.InterstitialAd;

public class AdManager {
    private InterstitialAd interstitialAd;

    public void loadInterstitialAd() {
        interstitialAd = new InterstitialAd(context);
        interstitialAd.setAdUnitId("YOUR_AD_UNIT_ID");
        
        AdRequest adRequest = new AdRequest.Builder().build();
        interstitialAd.loadAd(adRequest);
    }

    public void showInterstitialAd() {
        if (interstitialAd != null && interstitialAd.isLoaded()) {
            interstitialAd.show();
        }
    }
}

// OtherClass.java

public class OtherClass {
    private AdManager adManager;

    public void showAd() {
        adManager = new AdManager();
        adManager.loadInterstitialAd();
        adManager.showInterstitialAd();
    }
}