Question

我在RecyclerView中遇到Cardview问题。卡包含ImageView和Textbox。开始时，所有卡都在屏幕上，但是在屏幕上向下滚动并向上滚动之后，它们之间都是空白。

cardview布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:cardview="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center_horizontal">
    <android.support.v7.widget.CardView
        android:layout_width="fill_parent"
        android:layout_height="245dp"
        android:layout_gravity="center_horizontal"
        android:id="@+id/eventCardView"
        cardview:cardCornerRadius="5dp">
        <RelativeLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical">
            <ImageView
                android:layout_width="fill_parent"
                android:layout_height="240dp"
                android:layout_alignParentLeft="true"
                android:layout_alignParentTop="true"
                android:id="@+id/eventImage"
                android:scaleType="centerCrop" />
        </RelativeLayout>
    </android.support.v7.widget.CardView>
</LinearLayout>

适配器

using System.Collections.Generic;
using Android.Content;
using Android.Content.Res;
using Android.Support.V7.Widget;
using Android.Views;
using Android.Widget;
using EVENTS_MOBILE.Activities;
using EVENTS_MOBILE.CORE.Models;
using EVENTS_MOBILE.Utilities;

namespace EVENTS_MOBILE.Adapters
{
    public class RecyclerAdapter : RecyclerView.Adapter
    {
        private readonly List<SimplestEventModel> _events;
        private readonly RecyclerView _recyclerView;
        private readonly Context _context;
        public RecyclerAdapter(List<SimplestEventModel> events, RecyclerView recyclerView, Context context)
        {
            _context = context;
            _events = events;
            _recyclerView = recyclerView;
        }
        public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
        {
            if (holder is MyView myHolder)
            {
                //myHolder.Name.Text = _events[position].Name;

                //myHolder.Image.SetImageBitmap(ImageHelper.GetImageBitmapFromUrl(_events[position].ImageLink)); 
                myHolder.Image.SetImageResource((int)typeof(Resource.Drawable).GetField("test_image").GetValue(null));

            if (!myHolder.Image.HasOnClickListeners)
            {
                myHolder.Image.Click += delegate
                {
                    var intent = new Intent(_context, typeof(SingleEventActivity));
                    intent.PutExtra("eventId", position);
                    _context.StartActivity(intent);
                };
            }
            }
        }

        public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
        {
            View row = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.card_layout, parent, false);

            //TextView txtName = row.FindViewById<TextView>(Resource.Id.eventTitle);
            ImageView image = row.FindViewById<ImageView>(Resource.Id.eventImage);

            MyView view = new MyView(row)
            {
                //Name = txtName,
                Image = image
            };
            return view;
        }

        public override int ItemCount => _events.Count;

        public class MyView : RecyclerView.ViewHolder
        {
            public View MainView { get; set; }
            //public TextView Name { get; set; }
            public ImageView Image { get; set; }

            public MyView(View view) : base(view)
            {
                MainView = view;
            }
        }

    }
}

EventsFragment

using System;
using Android.OS;
using Android.Views;
using EVENTS_MOBILE.Adapters;
using EVENTS_MOBILE.CORE.Models;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Android.App;
using Android.Support.V7.Widget;
using Android.Widget;
using EVENTS_MOBILE.CORE.Services;

namespace EVENTS_MOBILE.Fragments
{
    public class EventsFragment : Fragment
    {
        protected EventsService EventsService;
        protected List<SimplestEventModel> Events = new List<SimplestEventModel>();
        protected RecyclerView _recyclerView;
        protected RecyclerView.LayoutManager LayoutManager;
        protected RecyclerView.Adapter Adapter;
        private ProgressBar _progressBar;


        public override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
        }

        private void LoadAllEvents(string category)
        {
            EventsService = new EventsService(category);
        }
        public override void OnActivityCreated(Bundle savedInstanceState)
        {
            base.OnActivityCreated(savedInstanceState);
            FindViews();

            //Events = EventsService.GetAllEventsForCategory();

            Adapter = new RecyclerAdapter(MockSimpleEvents(), _recyclerView, this.Context);
            _recyclerView.SetAdapter(Adapter);

        }

        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            return inflater.Inflate(Resource.Layout.eventsFragment, container, false);
        }

        protected void FindViews()
        {
            _recyclerView = this.View.FindViewById<RecyclerView>(Resource.Id.recyclerView);
            _progressBar = this.View.FindViewById<ProgressBar>(Resource.Id.progressbar_view);

            LayoutManager = new LinearLayoutManager(this.Context);
            _recyclerView.SetLayoutManager(LayoutManager);
        }
}

EventsActivity

using System;
using Android.App;
using Android.OS;
using Android.Support.Design.Widget;
using Android.Support.V7.App;
using Android.Views;
using Android.Widget;
using EVENTS_MOBILE.Fragments;

namespace EVENTS_MOBILE.Activities
{
    [Activity(Label="EVENTS",Theme = "@style/Theme.AppCompat.Light.DarkActionBar")]
    public class EventsActivity : Activity
    {
        public string Email = String.Empty;
        public string Category = String.Empty;
        BottomNavigationView _bottomNavigation;
        protected override void OnCreate(Bundle savedInstanceState)
        {
            try
            {
                base.OnCreate(savedInstanceState);
                Email = Intent.GetStringExtra("email");
                Category = Intent.GetStringExtra("category");
                SetContentView(Resource.Layout.menu);

                _bottomNavigation = FindViewById<BottomNavigationView>(Resource.Id.bottom_navigation);
                _bottomNavigation.NavigationItemSelected += BottomNavigation_NavigationItemSelected;

                LoadFragment(Resource.Id.events);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                Console.WriteLine(e.StackTrace);
            }
        }

        private void BottomNavigation_NavigationItemSelected(object sender, BottomNavigationView.NavigationItemSelectedEventArgs e)
        {
            LoadFragment(e.Item.ItemId);
        }
        private void LoadFragment(int id)
        {
            FragmentTransaction fragmentTx = this.FragmentManager.BeginTransaction();

            switch (id)
            {
                case Resource.Id.events:
                    EventsFragment eventsFragment = new EventsFragment();
                    fragmentTx.Replace(Resource.Id.fragmentContainer, eventsFragment);
                    fragmentTx.AddToBackStack(null);
                    fragmentTx.Commit();
                    break;
                case Resource.Id.map:
                    var nearestEventsFragment = new NearestEventsFragment();
                    fragmentTx.Replace(Resource.Id.fragmentContainer, nearestEventsFragment);
                    fragmentTx.AddToBackStack(null);
                    fragmentTx.Commit();
                    break;
                case Resource.Id.observed:
                    WatchListFragment watchlistfragment = new WatchListFragment(Email);
                    fragmentTx.Replace(Resource.Id.fragmentContainer, watchlistfragment);
                    Bundle args = new Bundle();
                    args.PutString("Email", Email);
                    watchlistfragment.Arguments = args;
                    fragmentTx.AddToBackStack(null);
                    fragmentTx.Commit();
                    break;
            }
        }
    }
}

menu.axml（片段容器）

<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@drawable/gradient">
  <FrameLayout
    android:id="@+id/fragmentContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
  <android.support.design.widget.BottomNavigationView
    android:id="@+id/bottom_navigation"
    android:layout_width="match_parent"
    android:layout_height="70dp"
    android:layout_gravity="start"
    android:layout_alignParentBottom="true"
    app:elevation="16dp"
    android:background="@drawable/gradient"
    app:itemIconTint="@drawable/nav_item_color"
    app:itemTextColor="@drawable/nav_item_color"
    app:menu="@menu/bottom_navigation_bar" />
</RelativeLayout>

此视图的

eventsFragment.axml布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/recyclerView" />
</LinearLayout>

开始时一切正常： https://i.stack.imgur.com/9j7Pp.png

但是在滚动后看起来像这样：https://i.stack.imgur.com/gG6q5.png

有人知道这种奇怪的行为吗？

Answer 1

卡片视图xml中的根LinearLayout的宽度和高度都使用fill_parent：

android:layout_width="fill_parent"
android:layout_height="fill_parent"

将高度更改为wrap_content，这应该可以解决问题。

滚动时显示空白的Cardview

1 个答案: