Question

我有一个列表视图，当单击ListView上的按钮时，它应该更改ListView外部的TextView文本。

我试过了：

初始化ViewHolder中的TextView

并在主类中具有一个函数，当单击ListView中的按钮时将调用该函数。

无论采用哪种方法，我都会在按钮上获得空引用。

public class ItemOrderActivity : BaseActivity <ItemOrderViewModel>
        {
            TextView estimatedTotal;
            Button continueButton;
            ListView itemList;
            int count = 0;
            static public int[] itemCount = new int[8] { 0, 0, 0, 0, 0, 0, 0, 0 };

        protected override void OnCreate (Bundle bundle)
        {
            base.OnCreate (bundle);

            // Setting layout
            SetContentView (Resource.Layout.ItemOrderLayout);

            estimatedTotal = FindViewById<TextView> (Resource.Id.estimatedTotal);

            // Initializing button view items
            continueButton = FindViewById<Button> (Resource.Id.continueButton);
            garmentList = FindViewById<ListView> (Resource.Id.itetListView);
            ItemListAdapter adapter = new ItemListAdapter(this, getItems());
            itemList.Adapter = adapter;

            // Button event for OnContinue
            continueButton.Click += OnContinue;

        }

        void total()
        {
            estimatedTotal.Text = "tet";
        }

        private class ItemListAdapter : BaseAdapter<Item>
        {
            private Activity activity;
            public List<Item> data;

            public ItemListAdapter(Activity activity, List<Item> data)
            {
                this.activity = activity;
                this.data = data;
            }

            public override Item this[int position]
            {
                get { return this.data [position]; }
            }

            public override int Count
            {
                get { return this.data.Count(); }
            }

            public override long GetItemId(int position)
            {
                return 0;
            }

            public override View GetView(int position, View convertView, ViewGroup parent)
            {
                Holder holder;
                holder = new Holder ();
                if (convertView == null) 
                {
                    convertView = this.activity.LayoutInflater.Inflate (Resource.Layout.ItemLayout, null);
                    //holder = new Holder ();
                    holder.Initialize (convertView);
                    convertView.Tag = holder;
                }

                //convertView.Tag = holder;
                Item item = this.data [position];
                holder = (Holder)convertView.Tag;
                holder.Bind (this.activity, item.itemName, position);

                return convertView;

            }

            public class Holder : Java.Lang.Object
            {
                public TextView ItemName;
                public Button removeItem;
                public Button addItem;
                public TextView itemQty;
                public int pos;
                //TextView estimatedTotal;

                public void Initialize(View view)
                {
                    itemName = view.FindViewById<TextView> (Resource.Id.itemTextView);
                    itemGarment = view.FindViewById<Button> (Resource.Id.removeItemButton);
                    itemGarment = view.FindViewById<Button> (Resource.Id.addItemButton);
                    itemQty = view.FindViewById<TextView> (Resource.Id.ItemQtyTextView);
                    //estimatedTotal = view.FindViewById<TextView> (Resource.Id.estimatedTotal);

                    addItem.Click += addItemClick;
                    removeItem.Click += removeItemClick;
                }

                public void Bind(Activity context, string gn, int position)
                {
                    garmentName.Text = gn;
                    garmentQty.Text = ItemOrderActivity.ItemCount[position].ToString();
                    pos = position;
                }

                public void addButtonClick(object sender, EventArgs e)
                {
                    poa.addItem (pos);

                    ItemOrderActivity.itemCount [pos]++;
                    itemQty.Text = ItemOrderActivity.itemCount [pos].ToString ();
                    //estimatedTotal.Text = "test";
                   poa.total();
                }
       }
}

Answer 1

从按钮获取回调的方式是错误的。去做这个：在适配器中创建一个事件以单击按钮。如果要设置listview适配器，请为更改textview文本的事件添加回调。在GetView内部或在活页夹中（或绑定视图的任何位置），将事件的处理程序添加到按钮单击事件中。所以在你的活动中：

protected override void OnCreate (Bundle bundle)
    {
        //Anything before it

        ItemListAdapter adapter = new ItemListAdapter(this, getItems());
        adapter.ItemButtonClick += delegate {//Anything you want to do};
        itemList.Adapter = adapter;

    }

和你的适配器：

private class ItemListAdapter : BaseAdapter<Item>
    {
       //Anything
       public override View GetView(int position, View convertView, ViewGroup parent)
        {
           //Your code for initializing
           if(ItemButtonClick!=null)
           theButton.Click += ItemButtonClick;
        }
    public event EventHandler ItemButtonClick;
    }

单击ListView中的按钮时，在ListView外部更改TextView文本

1 个答案: