Mono For Android 实现索引分段器效果

时间：2023-03-09 03:29:22
Mono For Android 实现索引分段器效果

这两天看了个Demo，自己也动手写了下，觉得效果还不错，分享一下！

主要是利用ListActivity中自带了一个ListView和ListAdapter来实现的，当然也可以在一般的Activity中添加ListView和ListAdapter来实现。具体代码如下：

显示自定义的适配器的实现：

//HomeScreenAdapter.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using Android.App;

using Android.Content;

using Android.OS;

using Android.Runtime;

using Android.Views;

using Android.Widget;

namespace ListViewAdapter

{

    [Activity(Label = "ListViewAdapter")]

    public class HomeScreenAdapter : BaseAdapter<string>

    {

        private string[] items;

        private Activity context;

        public HomeScreenAdapter(Activity context, string[] items)

            : base()

        {

            this.context = context;

            this.items = items;

        }

        public override string this[int position]

        {

            get { return items[position]; }

        }

        public override int Count

        {

            get { return items.Length; }

        }

        public override long GetItemId(int position)

        {

            return position;

        }

        public override View GetView(int position, View convertView, ViewGroup parent)

        {

            View view = convertView;

            if (view == null)

            {

                view = context.LayoutInflater.Inflate(Android.Resource.Layout.SimpleListItem1, null);

            }

            view.FindViewById<TextView>(Android.Resource.Id.Text1).Text = items[position];

            return view;

        }

    }

}

自定义适配器实现之后，只要将它赋给ListActivity中ListAdapter成员就可以了。

下面看看主类HomeScreen.cs的实现：

using System;

using System.Collections.Generic;

using System.IO;

using System.Text;

using Android.App;

using Android.Content;

using Android.Runtime;

using Android.Views;

using Android.Widget;

using Android.OS;

namespace SectionIndex

{

    [Activity(Label = "SectionIndex", MainLauncher = true, Icon = "@drawable/icon")]

    public class HomeScreen : ListActivity

    {

        private string[] items;

        protected override void OnCreate(Bundle bundle)

        {

            base.OnCreate(bundle);

            //用于存放文本文件的List

            List<string> veges = new List<string>();

            //利用流来打开文本文件

            Stream seedDataStream = Assets.Open(@"VegeData.txt");

            //将文本文件内容读入veges中

            //StringBuilder sb = new StringBuilder();

            using (StreamReader reader = new StreamReader(seedDataStream))

            {

                while (!reader.EndOfStream)

                {

                    veges.Add(reader.ReadLine());

                }

            }

            //将veges中的元素进行排序,比较器为匿名函数构成的委托

            veges.Sort((x,y)=>{ return x.CompareTo(y); } );

            //将列表中的元素存入数组中

            items = veges.ToArray();

        }

        protected override void OnListItemClick(ListView l, View v, int position, long id)

        {

            var t = items[position];

            Toast.MakeText(this, t, ToastLength.Short).Show();

            Console.WriteLine("Clicked on: " + t);

        }

    }

}

　　其中VegesData.txt为要读取的文本文件：其内容如下：

Beet greens

Bitterleaf

Bok choy

Broccoli Rabe

Brussels sprout

Cabbage

Catsear

Celery

Celtuce

Ceylon spinach

Chard

Chaya

Chickweed

Chicory

Chinese cabbage

Chinese Mallow

Chrysanthemum leaves

Collard greens

Corn salad

Cress

Dandelion

Endive

Epazote

Fat hen

Fiddlehead

Fluted pumpkin

Garden Rocket

Golden samphire

Good King Henry

Greater Plantain

Kai-lan

Kale

Komatsuna

Kuka

Lagos bologi

Lamb's lettuce

Land cress

Lettuce

Lizard's tail

Melokhia

Mizuna greens

Mustard

Napa cabbage

New Zealand Spinach

Orache

Pak choy

Paracress

Pea sprouts/leaves

Poke

Radicchio

Samphire

Sea beet

Sea kale

Sierra Leone bologi

Soko

Sorrel

Spinach

Summer purslane

Swiss chard

Tatsoi

Turnip greens

Watercress

Water spinach

Winter purslane

Yarrow

Avocado

Bell pepper

Bitter melon/Bitter gourd

Courgette

Cucumber

Ivy Gourd

Eggplant/Aubergine/Brinjal

Pumpkin

Squash

Sweet corn aka corn; aka maize

Sweet pepper

Tinda

Tomatillo

Tomato

Winter melon

West Indian gherkin

Zucchini

Artichoke

Broccoli

Cauliflower

Courgette flowers

Squash blossoms

American groundnut

Azuki bean

Black-eyed pea

Chickpea

Common bean

Drumstick

Dolichos bean

Fava bean

Garbanzo

Green bean

Guar

Gumbo

Horse gram

Indian pea

Lentil

Lima Bean

Moth bean

Mung bean

Okra

Pea

Peanut

Pigeon pea

Ricebean

Runner bean

Snap pea

Snow pea

Soybean

Tarwi

Tepary bean

Urad bean

Velvet bean

Winged bean

Yardlong bean

Asparagus

Cardoon

Celeriac

Celery

Elephant Garlic

Florence fennel

Garlic

Kohlrabi

Kurrat

Leek

Lotus root

Nopal

Onion

Spring Onion/Scallion

Prussian asparagus

Shallot

Welsh onion

Wild leek

Ahipa

Arracacha

Bamboo shoot

Beetroot

Burdock

Broadleaf arrowhead

Camas

Canna

Carrot

Cassava

Chinese artichoke

Daikon

Earthnut pea

Elephant Foot yam

Ensete

Ginger

Gobo

Hamburg parsley

Jerusalem artichoke

Jícama

Manioc

Mooli

Parsnip

Pignut

Plectranthus

Potato

Prairie turnip

Radish

Horseradish

Rutabaga

Salsify

Scorzonera

Skirret

Swede

Sweet Potato or Kumara

Taro

Ti

Tigernut

Turnip

Ulluco

Water chestnut

Yacón

Yam

　　关键部分就是如何实现ISectionIndexer这个接口。

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