Java 我的createFragment方法应该如何返回我的片段？

底部的返回值应该是多少？通过设置null，我可以使我的应用程序正常工作。然而，我想在不抑制它的情况下消除Android Studio中的警告

Android Studio显然在告诉我“'null'由声明为@NonNull的方法返回”

有没有更好的办法归还我的碎片

@NonNull
@Override
public Fragment createFragment(int position) {
    String className = mContext.getClass().getSimpleName();

    // Check which Activity is using the ViewHolder and return the appropriate Fragments.
    switch (className) {
        case "VancouverActivity":
            if (position == 0) {
                return new VancouverMainFragment();
            } else if (position == 1) {
                return new VancouverAttractionsFragment();
            } else if (position == 2) {
                return new VancouverCoffeeFragment();
            } else if (position == 3) {
                return new VancouverRestaurantFragment();
            } else {
                return new VancouverActivitiesFragment();
            }
        case "SaskatoonActivity":
            if (position == 0) {
                return new SaskatoonMainFragment();
            } else if (position == 1) {
                return new SaskatoonAttractionsFragment();
            } else if (position == 2) {
                return new SaskatoonCoffeeFragment();
            } else if (position == 3) {
                return new SaskatoonRestaurantFragment();
            } else {
                return new SaskatoonActivitiesFragment();
            }
        case "TorontoActivity":
            if (position == 0) {
                return new TorontoMainFragment();
            } else if (position == 1) {
                return new TorontoAttractionsFragment();
            } else if (position == 2) {
                return new TorontoCoffeeFragment();
            } else if (position == 3) {
                return new TorontoRestaurantFragment();
            } else {
                return new TorontoActivitiesFragment();
            }
        case "StJohnsActivity":
            if (position == 0) {
                return new StJohnsMainFragment();
            } else if (position == 1) {
                return new StJohnsAttractionsFragment();
            } else if (position == 2) {
                return new StJohnsCoffeeFragment();
            } else if (position == 3) {
                return new StJohnsRestaurantFragment();
            } else {
                return new StJohnsActivitiesFragment();
            }
    }
    return null;
}

---

您需要涵盖所有可能的退货案例，所以这是应该的。只需在使用此返回值的位置添加一个null检查，并将该方法标记为@Nullable。如果您确定已涵盖所有情况，您的方法可以通过抛出

IllegalArgumentException

来结束。