Question

我想知道如何创建一个包含多个视图持有者的回收站视图适配器，并且每次用该适配器实例化RecyclerView时，我只想查看特定类型，而不是混合类型。

我在Android活动中有2个不同的屏幕，每个屏幕都显示一个项目/卡片列表，一个是文本和数字，另一个是照片。现在，我为每个对象有2个不同的自定义适配器，而我想要实现的是一个适配器的灵活性，该适配器可以根据其显示的屏幕在对象类型之间进行延迟，并仅列出我需要的行。

我所看到的所有示例都是混合类型的对象，而这并不是我所追求的。

适配器代码附在下面。

rvalue

Answer 1

public class NotificationsAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private static final int VIEW_TYPE_REFERRAL_TRIGGER = 1;
    private static final int VIEW_TYPE_NOTIFICATION = 2;
    private static final int VIEW_TYPE_PROMOTION = 3;

    private List<Object> notificationObjectsList;
    private Activity mActivity;

    public NotificationsAdapter(Activity activity, List<Object> mNotificationList) {
        mActivity = activity;
        notificationObjectsList = new ArrayList<>(mNotificationList);
    }


    // Used to avoid the duplicate items recycling
    @Override
    public long getItemId(int position) {
        return position;
    }

    // Used to avoid the duplicate items recycling
    @Override
    public int getItemViewType(int position) {

        if ((notificationObjectsList.get(position) != null) && (notificationObjectsList.get(position) instanceof ReferralData)) {
            return VIEW_TYPE_REFERRAL_TRIGGER;
        } else if (notificationObjectsList.get(position) instanceof Promotion) {
            return VIEW_TYPE_PROMOTION;
        } else {
            return VIEW_TYPE_NOTIFICATION;
        }

    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        switch (viewType) {
            case VIEW_TYPE_REFERRAL_TRIGGER:
                return new NotificationsAdapter.ReferralTriggerViewHolder(inflater.inflate(R.layout.row_referral_trigger, parent, false));
            case VIEW_TYPE_NOTIFICATION:
                return new NotificationsAdapter.UserNotificationViewHolder(inflater.inflate(R.layout.row_layout_user_notification, parent, false));
            case VIEW_TYPE_PROMOTION:
                return new NotificationsAdapter.PromotionViewHolder(inflater.inflate(R.layout.row_layout_app_promotions, parent, false));
            default:
                return new NotificationsAdapter.UserNotificationViewHolder(inflater.inflate(R.layout.row_layout_user_notification, parent, false));
        }

    }

    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder viewHolder, final int position) {

        if (viewHolder instanceof PromotionViewHolder) {
            final PromotionViewHolder promotionViewHolder = (PromotionViewHolder) viewHolder;
            //populate data of promotion view holder

        } else if (viewHolder instanceof UserNotificationViewHolder) {
            final UserNotificationViewHolder notificationViewHolder = (UserNotificationViewHolder) viewHolder;
            //populate data of UserNotificationViewHolder view holder

        } else if (viewHolder instanceof ReferralTriggerViewHolder) {
            final ReferralTriggerViewHolder referralTriggerViewHolder = (ReferralTriggerViewHolder) viewHolder;
            //populate data of ReferralTriggerViewHolder view holder
        }
    }

    @Override
    public int getItemCount() {
        return notificationObjectsList.size();
    }


    private class UserNotificationViewHolder extends RecyclerView.ViewHolder {

        private UserNotificationViewHolder(View itemView) {
            super(itemView);

        }


    }

    private class PromotionViewHolder extends RecyclerView.ViewHolder  {

        private PromotionViewHolder(View itemView) {
            super(itemView);
        }


    }

    private class ReferralTriggerViewHolder extends RecyclerView.ViewHolder {
        ReferralTriggerView referralTriggerView;

        private ReferralTriggerViewHolder(View itemView) {
            super(itemView);
            referralTriggerView = itemView.findViewById(R.id.rtv_notification_adapter);
        }
    }

}

Answer 2

我不明白您的问题在哪里？您能否提供更多说明以实现您的目标？

//编辑

在您的代码中，您确定只有第一个项目将是VIEW0类型的项目，而其他项目将是VIEW1类型。这在getItemViewType(int position)函数中。

如果要确定选择哪种ViewHolder，则必须先选择它，然后再填充列表。在适配器中创建枚举：

enum TYPE {
    VIEW0,
    VIEW1
}

然后创建枚举变量：

private TYPE itemType;

并将其传递给您的构造函数：

public Test(ArrayList<MyDataProvider> _arrayList, TYPE itemType) {
    this.arrayList = new ArrayList<>();
    this.arrayList = _arrayList;
    this.itemType = itemType;
}

，然后在itemType函数中检查您的类型是什么（基于onCreateViewHolder变量）。请注意，switch中的变量是“ itemType”，而不是覆盖方法中的viewType。

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (itemType) {
    case VIEW0:
        return new NotificationsAdapter.ReferralTriggerViewHolder(inflater.inflate(R.layout.row_referral_trigger, parent, false));
    case VIEW1:
        return new NotificationsAdapter.UserNotificationViewHolder(inflater.inflate(R.layout.row_layout_user_notification, parent, false));
    default:
        return new NotificationsAdapter.UserNotificationViewHolder(inflater.inflate(R.layout.row_layout_user_notification, parent, false));
}

}

如何为多个视图持有者创建一个与所选视图持有人匹配的视图持有者视图适配器，而不是在同一回收者视图列表中

2 个答案: