如何在运行时用 ChildFragmentManager 和没有 PagerSlidingTabStrip Xamarin.Android 标题的片段替换片段

Posted 2023-04-18

【中文标题】如何在运行时用 ChildFragmentManager 和没有 PagerSlidingTabStrip Xamarin.Android 标题的片段替换片段

【英文标题】：How to Replace Fragment at runtime with the ChildFragmentManager and this fragment without Title of PagerSlidingTabStrip Xamarin.Android

【发布时间】：2021-07-21 11:00:36

【问题描述】：

我想在运行时使用其他片段更改分页器布局，但没有 PagerSlidingTabStrip 标题。我怎么能做到。 其次如何。我可以在另一个片段中调用方法主页片段。

这是首页布局

     <LinearLayout
            android:layout_
            android:layout_
            android:orientation="vertical"
            android:layout_marginBottom="50dp"
            android:id="@+id/SlidingStrips"
            android:layout_marginTop="10dp"
            android:layout_below="@id/AcountBalance">
     <com.refractored.PagerSlidingTabStrip
        android:id="@+id/tabs"
        android:layout_
        android:layout_
        android:background="?attr/colorPrimary"
        app:pstsPaddingMiddle="true"
        app:pstsDividerWidth="1dp"
        app:pstsDividerPadding="5dp"
        app:pstsDividerColor="#50FFFFFF"
        android:textColor="#50FFFFFF"
        app:pstsTextColorSelected="@android:color/white"
        app:pstsIndicatorColor="@android:color/white"
        app:pstsUnderlineColor="@android:color/white" />
<!--Change this to true if you want to center items-->
              
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_
        android:layout_
        android:layout_weight="1"
        tools:context=".HomeFragmentLayout" />
           
        </LinearLayout>

我在这里添加片段的方式是与父片段一起添加的 ChildFragments，这两个片段添加了两个带有小时和日期选项卡的选项卡。

 public class HomeFragment : Fragment, IOnTabReselectedListener, ViewPager.IOnPageChangeListener
    
        View view;
        private MyPagerAdapter adapter;
        private int count = 1;
        private int currentColor;
        List<Android.Support.V4.App.Fragment> fragments = new List<Android.Support.V4.App.Fragment>();
        public static ViewPager pager;
        private PagerSlidingTabStrip tabs;

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

            // Create your fragment here
        

        public static HomeFragment NewInstance()
        
            var frag1 = new HomeFragment  Arguments = new Bundle() ;
            return frag1;
        


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

            base.OnCreateView(inflater, container, savedInstanceState);
            if (view == null)
            
                view = inflater.Inflate(Resource.Layout.HomeFragmentLayout, container, false);
             
                return view;
            
            else
            

                return view;
            

        
        
        public override void OnViewCreated(View view, Bundle savedInstanceState)
        
            base.OnViewCreated(view, savedInstanceState);
            try
            
                fragments.Add(new HourlyFragment());
                fragments.Add(new DayFragment());
             
                adapter = new MyPagerAdapter(ChildFragmentManager, fragments);
                pager = view.FindViewById<ViewPager>(Resource.Id.pager);
                tabs = View.FindViewById<PagerSlidingTabStrip>(Resource.Id.tabs);
                pager.Adapter = adapter;
                tabs.SetViewPager(pager);

                var pageMargin = (int)TypedValue.ApplyDimension(ComplexUnitType.Dip, 4, Resources.DisplayMetrics);
                pager.PageMargin = pageMargin;
                pager.CurrentItem = 0;
                tabs.OnTabReselectedListener = this;
                tabs.OnPageChangeListener = this;
              
            
            catch (System.Exception ex)
            

               
            
        
        
       .// public  void ReplaceFragment(Fragment fragment)
        //
        //    try
        //    
        //        FragmentManager manager = ChildFragmentManager;
        //        FragmentTransaction transaction = manager.BeginTransaction();
        //        transaction.Add(Resource.Id.content_frame, fragment);
        //        transaction.Commit();
        //    
        //    catch (System.Exception ex)
        //    

               
        //    


        //

        public void OnTabReselected(int position)
        
            Toast.MakeText(Context.ApplicationContext, "Tab reselected: " + position, ToastLength.Short).Show();
        

        public void OnPageScrollStateChanged(int state)
        
            Console.WriteLine("Page scroll state changed: " + state);
        

        public void OnPageScrolled(int position, float positionOffset, int positionOffsetPixels)
        
            Console.WriteLine("Page Scrolled");
        

        public void OnPageSelected(int position)
        
            Console.WriteLine("Page selected: " + position);
        
        
    

这是寻呼机适配器

public class MyPagerAdapter : FragmentPagerAdapter
    
        List<Android.Support.V4.App.Fragment> fragments;
        private readonly string[] Titles =
        
            "Hour", "Day"
        ;

        public MyPagerAdapter(FragmentManager fm, List<Android.Support.V4.App.Fragment> fragments) : base(fm)
        
            this.fragments = fragments;

        
        public override ICharSequence GetPageTitleFormatted(int position)
        
      
            return new String(Titles[position]);
        

   
        //
        public override int Count  get  return fragments.Count;  

        public override Fragment GetItem(int position)
        
            return fragments[position];
        

        public override long GetItemId(int position)
        
            return base.GetItemId(position);
        
       

【参考方案1】：

你可以像下面这样，假设你需要调用 HomeFragment 中的替换方法。

在您的 MyPagerAdapter 类中添加以下代码（如何在运行时替换片段）：

private bool[] flags;
public override int GetItemPosition(Java.Lang.Object @object)
    
        return PositionNone;
    

public override Java.Lang.Object InstantiateItem(ViewGroup container, int position)
    

        if (flags != null && flags[position])
        
            /** Get the cached fragment and replace it with a new fragment*/
            Android.Support.V4.App.Fragment fragment = (Android.Support.V4.App.Fragment)base.InstantiateItem(container, position);
            string fragmentTag = fragment.Tag;
            Android.Support.V4.App.FragmentTransaction ft = fm.BeginTransaction();
            ft.Remove(fragment);
            fragment = fragments[position];
            ft.Add(container.Id, fragment, fragmentTag);
            ft.Attach(fragment);
            ft.Commit();
            /** Set to false when the replacement is complete*/
            flags[position] = false;
            if (fragment != null)
            
                return fragment;
            
            else
            
                return base.InstantiateItem(container, position);
            
        
        else
        
            return base.InstantiateItem(container, position);
        

        
    
  public void setFragments(List<Android.Support.V4.App.Fragment> fragments)
    
        if (this.fragments != null)
        
            flags = new bool[fragments.Count];
            for (int i = 0; i < fragments.Count; i++)
            
                flags[i] = true;
            
        
        this.fragments = fragments;
        NotifyDataSetChanged();
    

然后是 HomeFragment 中的 replace 方法：

  public void ReplaceFragment()
    
        fragments[0] = new NewFragment(); //suppose you want to replace the first HourlyFragment
        fragments[1] = new DayFragment();
        adapter.setFragments(fragments);


    

在另一个片段中（例如点击事件），您可以调用 HomeFragment 中的 replace 方法，如：

 private void Button_Click(object sender, EventArgs e)
    
        foreach (Android.Support.V4.App.Fragment fragment in Activity.SupportFragmentManager.Fragments)
        
            if (fragment is HomeFragment)
            
                ((HomeFragment)fragment).ReplaceFragment();