从选项卡 1 中选择 ListView 后切换到选项卡 2

问题描述

这是一个完整的项目:Google 云端硬盘.

Here is a complete project: Google Drive.

关注代码:

Frag_Home_1_Tab.cs:

public class Frag_Home_1_Tab : Fragment
    {
        public override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
        }

        public static Frag_Home_1_Tab NewInstance()
        {
            return new Frag_Home_1_Tab { Arguments = new Bundle() };
        }


        public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
        {
            View inflate = inflater.Inflate(Resource.Layout.frag_tab1, container, false);

            ListView mListView = inflate.FindViewById<ListView>(Resource.Id.listView);

            ViewPager viewPager = inflate.FindViewById<ViewPager>(Resource.Id.viewPager);

            mListView.ItemClick += (sender, e) =>
            {
                mListView.SetItemChecked(e.Position, true);

                // ** Here, how to navigate to tab 2 and refresh gridview **
            };

            ArrayAdapter<string> adapter = new ArrayAdapter<string>(Activity, Android.Resource.Layout.SimpleListItemActivated1, List());

            mListView.Adapter = adapter;

            // Set the ChoiceMode
            mListView.ChoiceMode = ChoiceMode.Single;

            // Select default
            mListView.SetItemChecked(0, true);

            return inflate;
        }

        private List<string> List()
        {
            List<string> list = new List<string>
            {
                "List 1",
                "List 2",
                "List 3",
                "List 4",
                "List 5",
                "List 6",
                "List 7",
                "List 8",
                "List 9"
            };

            return list;
        }
    }

frag_tab1:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <ListView
        android:minWidth="25px"
        android:minHeight="25px"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listView" />
</LinearLayout>

如果您从选项卡 1 的List5"列表中选择，则在选项卡 2 的网格视图中加载 5 行并导航到选项卡 2.

If you select from the "List5" list in tab 1, load 5 rows in the gridview of tab 2 and navigate to tab 2.

如果从选项卡 1 的List9"列表中选择，则在选项卡 2 的网格视图中加载 9 行并导航到选项卡 2.

If you select from the "List9" list in tab 1, load 9 rows in the gridview of tab 2 and navigate to tab 2.

如果您从选项卡 1 的List2"列表中选择，则在选项卡 2 的网格视图中加载 2 行并导航到选项卡 2.

If you select from the "List2" list in tab 1, load 2 rows in the gridview of tab 2 and navigate to tab 2.

就这样……

我想说的是:当您点击标签按钮 1 时导航到标签 2.就这么简单.

What I'm trying to say is: navigate to tab 2 when you click on tab button 1. Simple like that.

有什么解决办法吗?

推荐答案

Frag_Home_1:

public class Frag_Home_1 : Fragment
{
    TabLayout tabLayout;
    private static class SingletonHolder
    {
        public static Frag_Home_1 INSTANCE = new Frag_Home_1();
    }
    public static Frag_Home_1 getInstance()
    {
        return SingletonHolder.INSTANCE;
    }


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

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        View inflate = inflater.Inflate(Resource.Layout.frag_home_1, container, false);

        ViewPager viewPager = inflate.FindViewById<ViewPager>(Resource.Id.viewPager);
        MyFragmentPagerAdapter adapter = new MyFragmentPagerAdapter(ChildFragmentManager);
        viewPager.Adapter = adapter;

        //TabLayout
        tabLayout = inflate.FindViewById<TabLayout>(Resource.Id.sliding_tabs);
        tabLayout.SetupWithViewPager(viewPager);

        return inflate;
    }

    public void toTab2()
    {
        TabLayout.Tab tab = tabLayout.GetTabAt(1);
        tab.Select();
    }

    public class MyFragmentPagerAdapter : FragmentPagerAdapter
    {
        public string[] titles = new string[] { "Tab1", "Tab2" };
        List<Fragment> fgls = new List<Fragment>();
        public MyFragmentPagerAdapter(FragmentManager fm) : base(fm)
        {
            fgls.Add(Frag_Home_1_Tab.NewInstance());
            fgls.Add(Frag_Home_2_Tab.getInstance());
        }

        public override Fragment GetItem(int position)
        {
            return fgls[position];
        }

        public override ICharSequence GetPageTitleFormatted(int position)
        {

            return new String(titles[position]);
        }

        public override int Count
        {
            get { return titles.Length; }
        }
    }

}

Frag_Home_1_Tab 的 OnCreateView 方法:

mListView.ItemClick += (sender, e) =>
{
    mListView.SetItemChecked(e.Position, true);
    Frag_Home_1.getInstance().toTab2();
    Frag_Home_2_Tab.getInstance().updateGrid(e.Position);
    // ** Here, how to navigate to tab 2 and refresh gridview **
};

Frag_Home_2_Tab:

public class Frag_Home_2_Tab : Fragment,adapterUpdate
{
    ArrayAdapter<string> adapter;
    List<string> numbers = new List<string>();
    GridView grid;
    public override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
    }
    private static class SingletonHolder
    {
        public static Frag_Home_2_Tab INSTANCE = new Frag_Home_2_Tab();
    }
    public static Frag_Home_2_Tab getInstance()
    {
        return SingletonHolder.INSTANCE;
    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {

        initData(9);
        View view = inflater.Inflate(Resource.Layout.frag_tab2, container, false);
        grid = (GridView)view.FindViewById(Resource.Id.gridview);

        grid.ChoiceMode = ChoiceMode.Single;

        grid.ItemClick += (sender, e) =>
        {
            grid.SetItemChecked(e.Position, true);
        };

        adapter = new ArrayAdapter<string>(Activity, Resource.Layout.item_tab_2, numbers);

        grid.Adapter = adapter;

        return view;
    }

    private void initData(int count)
    {
        numbers.Clear();
        for (int i = 0; i < count; i++)
        {
            numbers.Add((i + 1).ToString());
        }
    }

    public void updateGrid(int count)
    {
        initData(count+1);
        adapter = new ArrayAdapter<string>(Activity, Resource.Layout.item_tab_2, numbers);
        grid.Adapter = adapter;
    }
}

public interface adapterUpdate
{
    void updateGrid(int count);
}

在Frag_Home_1 和Frag_Home_2_Tab 中，我使用单个实例来避免NullPointException.

In Frag_Home_1 and Frag_Home_2_Tab, I use single instance to avoid NullPointException.

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