ViewModel に recyclerView_id を管理させ、RecyclerView アダプタがアタッチ、デタッチされたとき recyclerView_id を変化させる。
アダプターが変化しなければ、recyclerView_id も変化しない。
ワーカースレッドで recyclerView_id を比較して更新の可否を決める。
意外とシンプルに判断できる。
public class MainViewModel extends ViewModel {
private MutableLiveData< RecyclerView> recyclerView = null;
public MutableLiveData< RecyclerView> getRecyclerView() {
if ( recyclerView == null ) {
recyclerView = new MutableLiveData< RecyclerView>(null);
recyclerView_id = 0;
}
return recyclerView;
}
public RecyclerView getValueRecyclerView() {
return getRecyclerView().getValue();
}
private long recyclerView_id;
public void setRecyclerView(RecyclerView rv) {
getRecyclerView().setValue(rv);
recyclerView_id++;
}
public void clearRecyclerView() {
if ( getRecyclerView() != null && getRecyclerView().getValue() != null ) {
getRecyclerView().getValue().setAdapter(null);
getRecyclerView().setValue(null);
recyclerView_id++;
}
}
public long getValueRecyclerViewID() {
return recyclerView_id;
}
//省略
}
public class MyAdapter extends RecyclerView.Adapter {
private final MainViewModel mViewModel;
private RecyclerView myRecyclerView = null;
private View.OnClickListener myListener;
//省略
public MyAdapter(MainViewModel viewModel, View.OnClickListener listener) {
mViewModel = viewModel;
myListener = listener;
//省略
}
@Override
public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
myRecyclerView = recyclerView;
mViewModel.setRecyclerView(myRecyclerView);//****
}
@Override
public void onDetachedFromRecyclerView(@NonNull RecyclerView recyclerView) {
myRecyclerView = null;
mViewModel.setRecyclerView(null);//****
super.onDetachedFromRecyclerView(recyclerView);
}
//省略
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
if (getItemCount() <= 0) return;
Bitmap bitmap = loadImage(myImageAbsPaths.get(position));
if (bitmap != null)
holder.imageView.setImageBitmap(bitmap);
else {
holder.imageView.setImageBitmap(
BitmapFactory.decodeResource(mMainModel.getContext().getResources(), R.drawable.img_file));
MyAsyncTask2 mAsyncTask = new MyAsyncTask2(mViewModel, myRecyclerView, position);
mAsyncTask.execute(myImageAbsPaths.get(position));
}
holder.textView.setText(String.valueOf(position + 1));
initStartPositionOffset(holder.linearLayout, position);
holder.linearLayout.setId(holder.getAdapterPosition());
holder.linearLayout.setOnClickListener(myListener);
}
//省略
}
public class MyAsyncTask2 {
private MainViewModel mViewModel;
private RecyclerView mRecyclerView;
private final int vID;
private long mRecyclerView_id = 0;
//省略
public MyAsyncTask2(MainViewModel data, RecyclerView rv, int id ) {
super();
mViewModel = data;
mRecyclerView = rv ;
vID = id;
mRecyclerView_id = data.getValueRecyclerViewID();
//省略
}
private class TaskRunnable implements Runnable {
private String targetPath = "";
public TaskRunnable(String param) { targetPath = param; }
@Override
public void run() {
//省略
new Handler(Looper.getMainLooper())
.post(() -> onPostExecute(result));
}
}
public void execute(String param) {
mViewModel.getValueExecutorService().submit(new TaskRunnable(param));// ワーカースレッド実行
}
void onPostExecute(int result) {
if ( mRecyclerView == null || mRecyclerView_id != mViewModel.getValueRecyclerViewID() ) {
finish();
return;
}
switch ( result ) {
case 0:
if ( vID < mRecyclerView.getAdapter().getItemCount() ) {
mRecyclerView.getAdapter().notifyItemChanged(vID);
}
break;
//省略
}
finish();
}
void finish() {
mRecyclerView = null;
mViewModel = null;
}
//省略
}
