Android错误:无法恢复空对象引用的activity Adview

<com.google.android.gms.ads.AdView
    xmlns:ads="http://schemas.android.com/apk/res-auto"
    android:id="@+id/adView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    ads:adSize="BANNER"
    ads:adUnitId="YOUR_AD_UNIT_ID">
</com.google.android.gms.ads.AdView>

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

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

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    // 保存必要的状态信息
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    // 恢复必要的状态信息
}

@Override
protected void onResume() {
    super.onResume();
    AdView adView = findViewById(R.id.adView);
    if (adView != null) {
        adView.resume();
    }
}

@Override
protected void onPause() {
    super.onPause();
    AdView adView = findViewById(R.id.adView);
    if (adView != null) {
        adView.pause();
    }
}