Question

我有两个片段和一个活动。 ChatFragment和UserListFragment。 ChatActivity是我写过代码的启动活动

protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            SetContentView(Resource.Layout.QChatLayout);

            var newFragment = new UserFragment(this, this);
            var ft = FragmentManager.BeginTransaction();
            ft.Add(Resource.Id.Frame_container, newFragment);
            ActionBar.NavigationMode = ActionBarNavigationMode.Tabs;
            var homeTab = ActionBar.NewTab();

            homeTab.SetTabListener(
                new TabListener<UserFragment>(newFragment));
            homeTab.SetText("Users");

            // Add the new tab to the action bar
            ActionBar.AddTab(homeTab);

            ft.Commit();
        }

它显示使用UserFragment的可用用户列表当我点击用户之一时，chatt窗口在新标签中打开，这只是ChatFragment 要打开新窗口，我在ActionBar中添加标签

User user = GetUserByName(userName);
                ChatFragment chatFragment = null;
                Fragment fragment = FragmentManager.FindFragmentByTag(user.Name);
                var ft = FragmentManager.BeginTransaction();
                if (fragment == null)
                {
                    chatFragment = new ChatFragment(context, activity);
                    chatFragment.User = user;
                    chatFragment.CurrentUser = Global.Host.Username;
                    Global.ChatWindows.Add(chatFragment);
                    ft.SetBreadCrumbTitle(user.Name);
                    ft.Add(Resource.Id.Frame_container, chatFragment, user.Name);
                   var homeTab = this.activity.ActionBar.NewTab();

        homeTab.SetTabListener(
            new TabListener<ChatFragment>(fragment));
        homeTab.SetIcon(Resource.Drawable.QChatOffline);
        homeTab.SetText(userName);

        // Add the new tab to the action bar
        this.activity.ActionBar.AddTab(homeTab);                    }
                else
                {
                    chatFragment = (ChatFragment)fragment;
                }


                ft.Commit();
                chatFragment.ShowMessage(String.Format("{0} is {1}.", user.Name, m_chatWindowManager.GetStatusText(user.Status)), MessageType.Status);

我使用了tablistner类：

public class TabListener<T> : Java.Lang.Object, ActionBar.ITabListener
        where T : Fragment, new()
    {
        private T _fragment;

        /// <summary>
        /// initializes a new instance of the tab listener
        /// </summary>
        public TabListener()
        {
            _fragment = new T();
        }

        /// <summary>
        /// Initializes a new instance of the tab listener
        /// </summary>
        /// <param name="fragment"></param>
        public TabListener(T fragment)
        {
            _fragment = fragment;
        }

        /// <summary>
        /// Handles the reselection of the tab
        /// </summary>
        /// <param name="tab"></param>
        /// <param name="ft"></param>
        public void OnTabReselected(ActionBar.Tab tab, FragmentTransaction ft)
        {

        }

        /// <summary>
        /// Adds the fragment when the tab was selected
        /// </summary>
        /// <param name="tab"></param>
        /// <param name="ft"></param>
        public void OnTabSelected(ActionBar.Tab tab, FragmentTransaction ft)
        {
            //ft.Add(Resource.Id.Frame_container, _fragment, typeof(T).FullName);
            //int index = Global.ChatWindows.FindIndex(c => c.User.Name == tab.Tag.ToString());
            //Activity.ActionBar.SelectTab(Activity.ActionBar.GetTabAt(index + 1));
            //ft.Show(_fragment);
            //tab.Select();
            //tab.Notify();
        }

        /// <summary>
        /// Removes the fragment when the tab was deselected
        /// </summary>
        /// <param name="tab"></param>
        /// <param name="ft"></param>
        public void OnTabUnselected(ActionBar.Tab tab, FragmentTransaction ft)
        {
            //ft.Remove(_fragment);
            //ft.AddToBackStack(tab.Tag.ToString());
        }
    }

我应该在OnTabSelected和Deselected中编写什么代码。我无法在操作栏中的标签之间切换。任何人都可以帮忙解决这个问题。

Answer 1

事情实际上很简单（我正在使用API级别14）并且记住它是我称为监听器类SimpleTabListener。

    public void OnTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
    {
        fragmentTransaction.Add(Resource.Id.fragment_container, fragment, typeof(T).Name);
    }

    public void OnTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
    {
        fragmentTransaction.Remove(fragment);
    }

我一直对您的问题感兴趣，因为我认为选项卡切换不能像Android教程演示那样正常工作。实际上，我在更新选项卡视图时犯了一个错误，并且在错误的方向上搜索解决方案几个小时。我在stackoverflow上看到了关于标签的其他问题，我认为你处于类似情况;-)。

编辑：事实上，似乎从android 3.2附加/分离是一个更好的想法切换标签，因为片段保存在FragmentManager中并删除视图。以前的方法是：

    public void OnTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
    {
        // Allows the view to be refreshed
        fragmentTransaction.Detach(fragment);
        fragmentTransaction.Attach(fragment);          
    }

    public void OnTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
    {
        if (fragment == null)
        {
            fragment = Fragment.Instantiate(context, typeof(T).Namespace.ToLower() + "." + typeof(T).Name);
            fragmentTransaction.Add(Resource.Id.fragment_container, fragment);
        }
        else
        {
            fragmentTransaction.Attach(fragment);
        }
    }

    public void OnTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction)
    {
        if (fragment != null)
        {
            fragmentTransaction.Detach(fragment);
        }
    }

This blog post对这个主题非常有趣。

无法在Android单选项卡之间切换

1 个答案: