在我的应用程序中，我使用recycler view和数组列表作为适配器的数据源，问题是我从数组列表中删除索引后，我不知道如何删除视图来自recyclerview的索引导致应用程序有时崩溃。
这是我定义和初始化recycler view的片段。
public class PastClasses extends Fragment{
ArrayList<GetAllPastClasses> Pastclasslist;
View rootView;
Context mcontext;
RecyclerView rv;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.activity_main, container, false);
Bundle bn = getArguments();
Pastclasslist = (ArrayList<GetAllPastClasses>) bn.getSerializable("class_detailss");
mcontext = PastClasses.this.getActivity();
rv = (RecyclerView) rootView.findViewById(R.id.rv);
LinearLayoutManager llm = new LinearLayoutManager(mcontext);
rv.setLayoutManager(llm);
rv.setHasFixedSize(true);
PastClassesAdapter adapter = new PastClassesAdapter(Pastclasslist, mcontext);
//final Class_Details_PagerAdapter adapter = new Class_Details_PagerAdapter(getSupportFragmentManager(), 2);
rv.setAdapter(adapter);
return rootView;
}
这是Adapter类。在remove方法中，我从列表中删除了该项，但我不知道如何从recycler view中删除视图。
public class PastClassesAdapter extends RecyclerView.Adapter<PastClassesAdapter.PersonViewHolder> {
private static final String TAG = "CustomAdapter";
String STARTPOINT = "https://www.vario.fitness";
ArrayList<GetAllPastClasses> Pastclasslist;
CancelClass cnclass;
String user_id ="442";
public static class PersonViewHolder extends RecyclerView.ViewHolder {
CardView cv;
TextView txt_class_name; //txt_class_name
TextView txt_bsns_name;
ImageView img_class;
ImageView img_rate;
ImageView img_timer;
TextView txt_area_name;
TextView txt_time;
public PersonViewHolder(View itemView) {
super(itemView);
// Define click listener for the ViewHolder's View.
cv = (CardView) itemView.findViewById(R.id.cvPastClasses);
txt_class_name = (TextView) itemView.findViewById(R.id.txt_class_name);
txt_bsns_name = (TextView) itemView.findViewById(R.id.txt_bsns_name);
img_timer = (ImageView) itemView.findViewById(R.id.img_timer);
txt_area_name = (TextView) itemView.findViewById(R.id.txt_area_name);
txt_time = (TextView)itemView.findViewById(R.id.txt_time);
img_class= (ImageView) itemView.findViewById(R.id.img_class);
img_rate= (ImageView) itemView.findViewById(R.id.img_rate);
}
}
Context mcontext;
public PastClassesAdapter (ArrayList<GetAllPastClasses> Pastclasslist , Context mcontext) {
this.mcontext=mcontext;
this.Pastclasslist = Pastclasslist;
//System.out.println("size: "+Pastclasslist.size());
}
public int getItemCount() {
return Pastclasslist.size();
}
public void remove(GetAllPastClasses item) {
int position = Pastclasslist.indexOf(item);
Pastclasslist.remove(position);
notifyItemRemoved(position);
}
public PersonViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.content_main_pastclass, viewGroup, false);
PersonViewHolder pvh = new PersonViewHolder(v);
return pvh;
}
// String name, String date, int photoId, String rate, String review
public void onBindViewHolder(final PersonViewHolder personViewHolder, final int i) {
if (!checkNullity(Pastclasslist.get(i).getClassName())) {
personViewHolder.txt_class_name.setText(Pastclasslist.get(i).getClassName());
} else {
personViewHolder.txt_class_name.setText("GYM CLASS");
}
if (!checkNullity(Pastclasslist.get(i).getArea())) {
personViewHolder.txt_area_name.setText(Pastclasslist.get(i).getArea());
}
if (!checkNullity(Pastclasslist.get(i).getBusinessName())) {
personViewHolder.txt_bsns_name.setText(Pastclasslist.get(i).getBusinessName());
}
if (!checkNullity(Pastclasslist.get(i).getClassDuration()) && !checkNullity(Pastclasslist.get(i).getSchdDate())) {
personViewHolder.txt_time.setText(Pastclasslist.get(i).getSchdDate().substring(11, 16) + " | " + Pastclasslist.get(i).getClassDuration());
}
if (!checkNullity(Pastclasslist.get(i).getPhoto())) {
// personViewHolder.Userprofilepic.setImageResource((persons[i].getPhoto()));
Picasso.with(mcontext).load(Pastclasslist.get(i).getPhoto().replace("\\", "").replaceAll(" ", "%20"))
.error(R.mipmap.ic_launcher).into(personViewHolder.img_class);
} else if (checkNullity(Pastclasslist.get(i).getPhoto())) {
personViewHolder.img_class.setImageResource(R.mipmap.ic_launcher);
}
personViewHolder.img_rate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(mcontext);
alertDialogBuilder.setTitle("Cancel Class");
alertDialogBuilder.setMessage("Are you sure,You want to cancel this class");
alertDialogBuilder.setIcon(R.mipmap.ic_launcher);
alertDialogBuilder.setPositiveButton("yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg0, int arg1) {
//Toast.makeText(mcontext, "You clicked yes button", Toast.LENGTH_LONG).show();
MainActivity.pLoading.setMessage("Cancelling..");
MainActivity.pLoading.show();
// POJO class GetAllPastClasses
final OkHttpClient client = new OkHttpClient();
final HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
client.interceptors().add(interceptor);
Retrofit retrofit = new Retrofit.Builder().baseUrl(STARTPOINT).addConverterFactory(GsonConverterFactory.create())
.client(client).build();
RestInterface restInterface = retrofit.create(RestInterface.class);
System.out.println("i is : " + i);
Call<CancelClass> objInbox = restInterface.cancelThisClass(null, null, null, null, null);
try {
objInbox = restInterface.cancelThisClass(Pastclasslist.get(i).getResIdPk(),
Pastclasslist.get(i).getClassIdFk(), Pastclasslist.get(i).getSchdIdFk(), Pastclasslist.get(i).getWeekNoSch(),
user_id);
} catch (Exception ex) {
ex.printStackTrace();
}
objInbox.enqueue(new Callback<CancelClass>() {
@Override
public void onResponse(Response<CancelClass> response, Retrofit retrofit) {
cnclass = response.body();
if (cnclass.getSucc().equals("1")) {
Toast.makeText(mcontext, cnclass.getMsg(), Toast.LENGTH_LONG).show();
// Pastclasslist.get(i).setCanStatus("1");
remove(Pastclasslist.get(i));
} else {
Toast.makeText(mcontext, cnclass.getMsg(), Toast.LENGTH_LONG).show();
}
MainActivity.pLoading.dismiss();
}
@Override
public void onFailure(Throwable t) {
Toast.makeText(mcontext, cnclass.getMsg(), Toast.LENGTH_LONG).show();
}
});
}
});
alertDialogBuilder.setNegativeButton("No", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
AlertDialog alertDialog = alertDialogBuilder.create();
alertDialog.show();
}
});
}
public boolean checkNullity(String responseString) {
if (responseString == null || responseString.equals("") || responseString.equals("-1")) {
return true;
} else {
return false;
}
}
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
super.onAttachedToRecyclerView(recyclerView);
}
}
答案 0 :(得分：0)
当您从用于初始化适配器的arrayList对象中删除该项时，只需调用：
adapter.notifyDataSetChanged();
答案 1 :(得分：0)
我得到了答案，我只需要使用方法notifyItemChanged和notifyItemRangeChanged，以便适配器可以知道视图已被删除。当我将删除方法更改为下面的东西。
public void remove(GetAllPastClasses item) {
int position = Pastclasslist.indexOf(item);
Pastclasslist.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position,Pastclasslist.size());
}
答案 2 :(得分：0)
修改您的getItemCount()和remove()方法，如下所示：
public int getItemCount() {
return (null != Pastclasslist ? Pastclasslist.size() : 0);
}
remove()方法
public void remove(GetAllPastClasses item) {
int position = Pastclasslist.indexOf(item);
if(position!=-1 && position<Pastclasslist.size())
{
Pastclasslist.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, getItemCount());
}
}
notifyItemRangeChanged(position, getItemCount()); - 通知RecyclerView Adapter适配器中元素的位置已从位置更改（已删除元素索引到列表末尾），请更新它。
if(position!=-1 && position<Pastclasslist.size()) - 此条件验证元素的位置不等于-1，元素的位置应小于列表中总元素的大小。因此，不会因元素索引而导致意外崩溃。