Groupie: Update README instructions for converting existing ViewHolders
I'm using trying to convert an existing Java ViewHolder to use with Groupie. In the docs the only thing I can find about this is under the Kotlin section (I'm only sadly using Java and not Kotlin, but the Kotlin section was the only place that mentioned existing ViewHolders) and it says
If you're converting existing ViewHolders, you can leave them as they are by making an
Item<MyViewHolder>.
The way I interpret that is that, if I leave my existing ViewHolder alone I should be able to use it seamlessly with Groupie.
public static class MyViewHolder extends RecyclerView.ViewHolder {
//TextViews and stuff
public MyViewHolder(View itemView) {
super(itemView);
//Butterknife.bind(...)
}
//bindTo(){
//Method recommended by Yigit to be implemented in each VH to handle the actual binding
//}
}
This existing RecyclerView.ViewHolder lives in MyCustomAdapter.java
Now I go to create my Item since I want to use Groupie.
public class MyItem extends Item<MyCustomAdapter. MyViewHolder>{
@Override
public void bind(@NonNull MyCustomAdapter. MyViewHolder viewHolder, int position) {
//bind
}
@Override
public int getLayout() {
return R.layout.my_item;
}
}
I get an error message in the IDE on the first line of the last code snippet (public class MyItem extends Item< MyCustomAdapter. MyViewHolder>{) specifically under <MyCustomAdapter. MyViewHolder> that says
Type parameter
com.myapp.MyCustomAdapter.MyViewHolderis not within its bound; should extendcom.xwray.groupie.ViewHolder
bug
ColtonIdle
All 9 comments
Hi, sorry this wasn't clear!
Change MyViewHolder extends RecyclerView.ViewHolder to MyViewHolder extends com.xwray.groupie.ViewHolder.
I also updated the README to be more explicit. Hope that helps!
lisawray
on 3 Jan 2018
I'm using 2.0.0-alpha2 for now and changed MyViewHolder to extend from the Groupie Viewholder (as per your previous comment). Then I added groupAdapter.add(new MyItem()); in my Activity. Code compiles which is nice, but now I'm getting another error at runtime.
31357-31357/com.myapp.app E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.myapp.app, PID: 31357
java.lang.ClassCastException: com.xwray.groupie.ViewHolder cannot be cast to com.myapp.app.MyCustomAdapter$MyViewHolder
at com.myapp.app.MyItem.bind(MyItem.java:10)
at com.xwray.groupie.Item.bind(Item.java:63)
at com.xwray.groupie.Item.bind(Item.java:49)
at com.xwray.groupie.GroupAdapter.onBindViewHolder(GroupAdapter.java:89)
at com.xwray.groupie.GroupAdapter.onBindViewHolder(GroupAdapter.java:19)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6515)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5458)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5724)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5563)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5559)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2229)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1556)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1516)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:608)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3693)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3410)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3962)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:610)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1080)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1172)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
31357-31357/com.myapp.app E/AndroidRuntime: at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at com.android.internal.policy.DecorView.onLayout(DecorView.java:758)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2484)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2200)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1386)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6733)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
at android.view.Choreographer.doCallbacks(Choreographer.java:723)
at android.view.Choreographer.doFrame(Choreographer.java:658)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
31357-31357/com.myapp.app E/UncaughtException: java.lang.ClassCastException: com.xwray.groupie.ViewHolder cannot be cast to com.myapp.app.view.MyCustomAdapter$MyViewHolder
at com.myapp.app.MyItem.bind(MyItem.java:10)
at com.xwray.groupie.Item.bind(Item.java:63)
at com.xwray.groupie.Item.bind(Item.java:49)
at com.xwray.groupie.GroupAdapter.onBindViewHolder(GroupAdapter.java:89)
at com.xwray.groupie.GroupAdapter.onBindViewHolder(GroupAdapter.java:19)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6515)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5458)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5724)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5563)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5559)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2229)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1556)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1516)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:608)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3693)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3410)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3962)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:610)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1080)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1172)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
31357-31357/com.myapp.app E/UncaughtException: at com.android.internal.policy.DecorView.onLayout(DecorView.java:758)
at android.view.View.layout(View.java:19590)
at android.view.ViewGroup.layout(ViewGroup.java:6053)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2484)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2200)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1386)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6733)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
at android.view.Choreographer.doCallbacks(Choreographer.java:723)
at android.view.Choreographer.doFrame(Choreographer.java:658)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6541)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
If I remove groupAdapter.add(new MyItem()); then it runs, but it doesn't populate my recyclerView with anything which makes sense, but figured I'd throw it in.
ColtonIdle
on 5 Jan 2018
Update: I'm now using 2.0.0 instead of alpha 2 (since #139 was resolved), but I'm still getting the same issue.
ColtonIdle
on 5 Jan 2018
I was able to reproduce this and have a pretty good idea what's going on. Will try to fix over the weekend. Sorry for delay!
lisawray
on 5 Jan 2018
Awesome! Ability to repro is great news!
ColtonIdle
on 5 Jan 2018
@lisawray I'm facing the same issue as @ColtonIdle .
I am getting the same error when adding the item.
java.lang.ClassCastException: com.xwray.groupie.ViewHolder cannot be cast to com.juster.feature.record.extcam.ExtCamMediaHeader$MediaItemViewHolder
Is there any workaround?
aayushthakur
on 12 Jan 2018
I solved my problem by referring to issue #128
Just override createViewHolder and make it return new instance of your own view holder, as said by @lisawray
You can find my sample implementation below. :)
```
package com.juster.feature.record.extcam;
import android.support.annotation.NonNull;
import android.view.View;
import android.widget.TextView;
import com.juster.R;
import com.xwray.groupie.Item;
import com.xwray.groupie.ViewHolder;
public class ExtCamMediaHeader extends Item
private String mRoomName;
private int mMediaCount;
public ExtCamMediaHeader(String roomName, int mediaCount) {
this.mRoomName = roomName;
this.mMediaCount = mediaCount;
}
@NonNull
@Override
public MediaItemViewHolder createViewHolder(@NonNull View itemView) {
return new MediaItemViewHolder(itemView);
}
@Override
public void bind(@NonNull MediaItemViewHolder viewHolder, int position) {
viewHolder.tv_roomName.setText(mRoomName);
viewHolder.tv_mediaCount.setText(String.valueOf(mMediaCount));
}
@Override
public int getLayout() {
return R.layout.ext_cam_header;
}
class MediaItemViewHolder extends ViewHolder {
TextView tv_roomName, tv_mediaCount;
MediaItemViewHolder(View view) {
super(view);
tv_roomName = view.findViewById(R.id.tv_roomName);
tv_mediaCount = view.findViewById(R.id.tv_mediaCount);
}
}
}
````
aayushthakur
on 12 Jan 2018
👍1
Thank you so much @aayushthakur . It's unbelievable that I solved this problem and have now forgotten (twice) that I did so.
I will make a point to update the README to explain. It's not difficult but it's definitely not intuitive!
lisawray
on 12 Jan 2018
👍1
I updated the README to explicitly include a section on legacy viewholders. If you think it could be more clear PRs welcome :)
lisawray
on 15 Jan 2018
👍1
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