C# 从过时的FragementManager过渡到Android.Support.V4.App

我的应用程序中有几个

DialogFragement

，我需要转换到

Android.Support.V4.app.DialogFragment

，因此我的应用程序与API 29（Q）兼容。我首先将“更改密码”对话框片段代码转换为：

class ChangePassword : Android.Support.V4.App.DialogFragment 
{
    public event DialogEventHandler Dismissed;
    public string selection = "";
    private int error = 0;
    public User MyUser;

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        base.OnCreateView(inflater, container, savedInstanceState);
        View view = inflater.Inflate(Resource.Layout.ChangePassword, container, false);
        Button ok = view.FindViewById<Button>(Resource.Id.button_ok);
        EditText currentPassword = view.FindViewById<EditText>(Resource.Id.currentPassword);
        EditText newPassword1 = view.FindViewById<EditText>(Resource.Id.newPassword1);
        EditText newPassword2 = view.FindViewById<EditText>(Resource.Id.newPassword2);
        ok.Click += (sender, args) =>
        {
            if (currentPassword.Text != "" && (newPassword1.Text.ToUpper () == newPassword2.Text.ToUpper()) && (newPassword1.Text != "" || newPassword2.Text != ""))
            {
                ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
                OMLDataInterfaceWeb.OMLDataInterface datainterface = new OMLDataInterfaceWeb.OMLDataInterface();
                try
                {
                    datainterface.ChangeUserPassword(MyUser.Username, currentPassword.Text, newPassword1.Text);
                }
                catch (Exception e)
                {
                    error = 1;
                    Utils.showMessage(e.Message, "Error");
                }

                if (error == 0)
                {
                    selection = newPassword2.Text;
                    if (null != Dismissed)
                        Dismissed(this, new DialogEventArgs { Selection = selection });
                }
            }
            else
            {
                if (currentPassword.Text == "")
                {
                    // Android.Content.Context context = new AppContext() ;
                    Utils.showMessage("Enter the current password.","ERROR");
                }
                else
                {
                    if (newPassword1.Text == "")
                    {
                        Utils.showMessage("The first new password field is blank.", "ERROR");
                    } else if (newPassword2.Text == "")
                    {
                        Utils.showMessage("Please re-enter the new password.", "ERROR");

                    } else if (newPassword1.Text.ToUpper() != newPassword2.Text.ToUpper())
                    {
                        Utils.showMessage("The passwords do not match.", "ERROR");
                    }
                }
            }
        };

        return view;
    }
    public override void OnResume()
    {
        int width = 900; 
        int height = 900;
        Dialog.Window.SetLayout(width, height);
        base.OnResume();
    }
}

---

我在按钮点击代码中发现两个错误，第一个错误是

无法将类型'Android.App.FragmentManager'隐式转换为'Android.Support.V4.App.FragmentTransaction

，这发生在这行代码

Android.Support.V4.App.FragmentTransaction=FragmentManager

，假设我还必须使用

Android.Support.V4.App.

来限定

FragmentManager

，我将代码改为

Android.Support.V4.App.FragmentTransaction=Android.Support.V4.App.FragmentManager，这生成了错误“FragmentManager”是一种类型，在给定上下文中无效，另一个错误是
无法将类型“Android.App.Fragment”转换为“MyAndroidApp.ChangePassword”
，该错误发生在
ChangePassword\u exportFragment=（ChangePassword）FragmentManager.FindFragmentByTag行(“Dialog”）；
。我已经搜索了所有的ove以寻找答案，但我所做的任何尝试都无法解决此问题。我缺少什么？
我能够找到答案。新的按钮单击代码是：

        btnChangePassword.Click += (sender, e) =>
        {

            Android.Support.V4.App.FragmentTransaction transcation = SupportFragmentManager.BeginTransaction();
            ChangePassword changePassword = new ChangePassword();
            changePassword.MyUser = MyUser;
            changePassword.Show(transcation, "Dialog");

            changePassword.Dismissed += (s, a) => {
                /* do something with e.Selection here */

                if (a.Selection.ToUpper() != "")
                {
                    ChangePassword _exportFragment = (ChangePassword)SupportFragmentManager.FindFragmentByTag("Dialog");
                    if (_exportFragment != null)
                    {
                        _exportFragment.Dismiss();
                    }
                    changedPassword = true;
                   thePassword = a.Selection;
                }
                else
                {
                    Toast.MakeText(this, "Enter new password.", ToastLength.Long).Show();
                }
            };

除其他问题外，您的大小写与正确的大小写不匹配（所有包名称都应为小写），FragmentManager不同于FragmentTransaction，您应该真正转换为
androidx
版本：.support.v4已过时且未维护。如果您所说的包名是指
Android.support.v4.App
，那么Visual Studio 2019就不是这样了。也许我应该指出我的开发平台。
        btnChangePassword.Click += (sender, e) =>
        {

            Android.Support.V4.App.FragmentTransaction transcation = SupportFragmentManager.BeginTransaction();
            ChangePassword changePassword = new ChangePassword();
            changePassword.MyUser = MyUser;
            changePassword.Show(transcation, "Dialog");

            changePassword.Dismissed += (s, a) => {
                /* do something with e.Selection here */

                if (a.Selection.ToUpper() != "")
                {
                    ChangePassword _exportFragment = (ChangePassword)SupportFragmentManager.FindFragmentByTag("Dialog");
                    if (_exportFragment != null)
                    {
                        _exportFragment.Dismiss();
                    }
                    changedPassword = true;
                   thePassword = a.Selection;
                }
                else
                {
                    Toast.MakeText(this, "Enter new password.", ToastLength.Long).Show();
                }
            };