go back to previous fragment from another fragment that was started from recyclerview adapter (xamarin.android) - android-fragments

Question

so I have an application that is as follows:
login page where the user enters his credentials and can access the main app if his credentials are correct. and if he checks the remember me checkbox, his username and password will be saved in shared preferences so that he can directly go to the main app in the second time.
the main app has a tabbed layout with a viewpager. in one of the tabs, which is a fragment, I use a recyclerview to display data, that I get from a database, in rows.
now in each row there is a reply button that will show details corresponding to each row when clicked. the details will be shown in a new fragment.
so the point is that I managed to replace the tab's fragment with the new fragment using this code in the recyclerview's adapter:
public class recyclerviewAdapter : RecyclerView.Adapter
{
// Event handler for item clicks:
public event EventHandler<int> ItemClick;
List <summary_request> summary_Requests=new List<summary_request>();
//Context context;
public readonly stores_fragment context;
public recyclerviewAdapter(stores_fragment context, List<summary_request> sum_req)
{
this.context = context;
summary_Requests = sum_req;
}
public override RecyclerView.ViewHolder
OnCreateViewHolder(ViewGroup parent, int viewType)
{
View itemView = LayoutInflater.From(parent.Context).
Inflate(Resource.Layout.recycler_view_data, parent, false);
recyclerview_viewholder vh = new recyclerview_viewholder(itemView, OnClick);
return vh;
}
public override void
OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
{
recyclerview_viewholder vh = holder as recyclerview_viewholder;
vh.by_user.Text = summary_Requests[position].By;
vh.warehousename.Text = summary_Requests[position].warehousename;
vh.project.Text = summary_Requests[position].project;
vh.operations_note.Text = summary_Requests[position].destination_Note;
vh.source_Note.Text = summary_Requests[position].source_Note;
vh.stockType.Text = summary_Requests[position].stockType;
vh.requestStatus.Text = summary_Requests[position].requestStatus;
vh.reply.Click += delegate
{
summary_detail_req fragment = new summary_detail_req();
var fm = context.FragmentManager.BeginTransaction();
fm.Replace(Resource.Id.frameLayout1, fragment);
fm.AddToBackStack(null);
fm.Commit();
int nb = context.FragmentManager.BackStackEntryCount;
Toast.MakeText(context.Context, nb.ToString(), ToastLength.Long).Show();
};
}
private void Reply_Click(object sender, EventArgs e)
{
Toast.MakeText(context.Context, "reply" , ToastLength.Long).Show();
}
public override int ItemCount
{
get { return summary_Requests.Count; }
}
// Raise an event when the item-click takes place:
void OnClick(int position)
{
if (ItemClick != null)
ItemClick(this, position);
}
}
but my context.FragmentManager.BackStackEntryCount remain zero! I don't get it. in my main activity, I am using this code for the backpress function:
stores_fragment.recyclerviewAdapter adapter;
public override void OnBackPressed()
{
string userName = pref.GetString("Username", String.Empty);
string password = pref.GetString("Password", String.Empty);
if (userName != String.Empty || password != String.Empty && adapter.context.FragmentManager.BackStackEntryCount == 0)
{
this.FinishAffinity();
}
else
base.OnBackPressed();
}
but i'm not getting what i want. this function is getting me out of the whole app.the first part of the if statement is because without it, when the I press the back button from the main activity it takes me back to the login page and I don't want that.
my question is what should I do to manage my fragments and the backpress function?
thanks in advance.

Answer 1

so the point is that I managed to replace the tab's fragment with the new fragment using this code in the recyclerview's adapter
According to your description, you want to open another fragment from recyclerview Button.click, if yes, please take a look the following code:
on OnBindViewHolder
int selectedindex;
// Fill in the contents of the photo card (invoked by the layout manager):
public override void
OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
{
selectedindex =position;
PhotoViewHolder vh = holder as PhotoViewHolder;
// Set the ImageView and TextView in this ViewHolder's CardView
// from this position in the photo album:
vh.Image.SetImageResource(mPhotoAlbum[position].PhotoID);
vh.Caption.Text = mPhotoAlbum[position].Caption;
vh.btnreply.Click += Btnreply_Click;
}
To show detailed activity. MainActivity is the current activity for recyclerview.
private void Btnreply_Click(object sender, EventArgs e)
{
Showdetailed(selectedindex);
}
private void Showdetailed(int position)
{
var intent = new Intent();
intent.SetClass(MainActivity.mac, typeof(DetailsActivity));
intent.PutExtra("selectedid", position);
MainActivity.mac.StartActivity(intent);
}
The detailedactivity.cs:
public class DetailsActivity : Activity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your application here
var index = Intent.Extras.GetInt("selectedid", 0);
var details = DetailsFragment.NewInstance(index); // Details
var fragmentTransaction = FragmentManager.BeginTransaction();
fragmentTransaction.Add(Android.Resource.Id.Content, details);
fragmentTransaction.Commit();
}
}
The DetailsFragment.cs:
public class DetailsFragment : Fragment
{
public int ShownPlayId => Arguments.GetInt("selectedid", 0);
public static DetailsFragment NewInstance(int index)
{
var detailsFrag = new DetailsFragment { Arguments = new Bundle() };
detailsFrag.Arguments.PutInt("selectedid", index);
return detailsFrag;
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
// Use this to return your custom view for this Fragment
// return inflater.Inflate(Resource.Layout.YourFragment, container, false);
if (container == null)
{
// Currently in a layout without a container, so no reason to create our view.
return null;
}
var scroller = new ScrollView(Activity);
var text = new TextView(Activity);
var padding = Convert.ToInt32(TypedValue.ApplyDimension(ComplexUnitType.Dip, 4, Activity.Resources.DisplayMetrics));
text.SetPadding(padding, padding, padding, padding);
text.TextSize = 24;
Photo photo =PhotoAlbum.mBuiltInPhotos[ShownPlayId];
text.Text = photo.Caption;
scroller.AddView(text);
return scroller;
}
}
About implementing fragment, you can take a look:
https://learn.microsoft.com/en-us/samples/xamarin/monodroid-samples/fragmentswalkthrough/