Question

在我的自定义adadpter（RequestAdapter）中，我动态删除元素。我这样做是通过从我通过构造函数的对象的ArrayList中删除对象。一旦我在列表上使用remove（），我就调用notifyDataSetChanged（）。

问题是这个 - 从原始列表中删除了项目，但除了已删除项目之外的所有项目都附加到listView上。（如果我从列表[A B C]中删除A，最终结果是一个如下所示的列表 - [B C B C]。此外，如果我从这个列表中删除B，我得到这个 - [C B C C]

这是我使用的代码：

private HashMap<String,Object> tournamentStatus = new HashMap<>();

public RequestAdapter(Activity context, ArrayList<RequestDetails> requests){
    super(context,0,requests);
    this.mRequestsList = requests;
}

@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
    Log.d("Adapter getView()","Invoked");

    View listItemView = convertView;
    if(listItemView == null) {
        listItemView = LayoutInflater.from(getContext()).inflate(
                R.layout.request_list_item, parent, false);
    }

    final RequestDetails retrievedRequest = getItem(position);

    final boolean isOCRequest;
    final boolean isParticipantRequest;

    final TextView tournamentName = (TextView) listItemView.findViewById(R.id.request_textview_tournament_name);
    final TextView userName = (TextView) listItemView.findViewById(R.id.request_textview_user_name);
    final TextView requestType = (TextView) listItemView.findViewById(R.id.request_textview_request_type);
    final TextView sport = (TextView) listItemView.findViewById(R.id.request_textview_sport);
    final TextView userFaculty = (TextView) listItemView.findViewById(R.id.request_textview_user_faculty);
    final TextView userYear = (TextView) listItemView.findViewById(R.id.request_textview_user_year);

    if(retrievedRequest.isParticipantRequest()) {
        requestType.setText("Request Type: Participant");
        sport.setText("Sport: "+retrievedRequest.getSport());
    }
    else {
        requestType.setText("Request Type: Organizing Committee");
        sport.setVisibility(View.GONE);
    }
    tournamentRef = FirebaseDatabase.getInstance().getReference().child("Tournaments").child(retrievedRequest.getTournamentId());
    tournamentRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if(dataSnapshot.exists()){
                TournamentInformation tournamentInformation = dataSnapshot.getValue(TournamentInformation.class);
                tournamentName.setText(tournamentInformation.getTournamentName());
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });


    userRef = FirebaseDatabase.getInstance().getReference().child("Users").child(retrievedRequest.getUserId());
    userRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if(dataSnapshot.exists()){
                UserInformation user = dataSnapshot.getValue(UserInformation.class);
                userName.setText("User Name: "+user.getName());
                userFaculty.setText("Faculty: "+user.getFaculty());
                userYear.setText("Year: "+Integer.toString(user.getYear()));
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

    Button mAcceptButton = (Button) listItemView.findViewById(R.id.accept_request_button);
    Button mDenyButton = (Button) listItemView.findViewById(R.id.deny_request_button);

    mAcceptButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if(retrievedRequest.isParticipantRequest()){
                tournamentStatus.put("isOrganizing",false);
                tournamentStatus.put("isParticipating",true);
                userRef.child("sports").child(retrievedRequest.getTournamentId()).child(retrievedRequest.getSport()).setValue(true);
            }
            else if(retrievedRequest.isOCRequest()){
                tournamentStatus.put("isOrganizing",true);
                tournamentStatus.put("isParticipating",false);
            }


            Toast.makeText(getContext(),"Requested Accepted",Toast.LENGTH_SHORT).show();
            userRef.child("tournamentStatuses").child(retrievedRequest.getTournamentId()).updateChildren(tournamentStatus);


            DatabaseReference requestsRef = FirebaseDatabase.getInstance().getReference().child("Requests");
            requestsRef.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    if(dataSnapshot.exists()){
                        for(DataSnapshot requestLooper : dataSnapshot.getChildren()){
                            RequestDetails loopedRequest = requestLooper.getValue(RequestDetails.class);
                            if(loopedRequest.equals(retrievedRequest)){
                                requestLooper.getRef().removeValue();

                                Log.d("Removing at",requestLooper.getRef().toString());
                                Log.d("requestList",mRequestsList.toString());

                            }
                        }
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
            mRequestsList.remove(retrievedRequest);
            notifyDataSetChanged();
        }
    });

    mDenyButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            DatabaseReference requestsRef = FirebaseDatabase.getInstance().getReference().child("Requests");
            requestsRef.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    if(dataSnapshot.exists()){
                        for(DataSnapshot requestLooper : dataSnapshot.getChildren()){
                            RequestDetails requestDetails = requestLooper.getValue(RequestDetails.class);

                            if(requestDetails.equals(retrievedRequest)){
                                requestLooper.getRef().removeValue();

                                Log.d("Removing at",requestLooper.getRef().toString());
                                Log.d("requestList",mRequestsList.toString());

                                Toast.makeText(getContext(),"Requested Denied",Toast.LENGTH_SHORT).show();
                                break;
                            }
                        }
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

            mRequestsList.remove(retrievedRequest);
            notifyDataSetChanged();
        }
    });

    return listItemView;
}

我做了哪些更改，以便列表不重复？

更新我添加了整个适配器代码，但大部分内容都涉及设置textViews。我只在Accept和Deny按钮的clickListeners中删除

Answer 1

如果您不想在集合中重复，

List<String> al = new ArrayList<>();

//包括重复列表

private void removeDuplicate(ArrayList al)
{
    HashSet<String> hs = new HashSet<>();
    hs.addAll(al);
    al.clear();
    al.addAll(hs);
}

//在调用此方法后更改添加和删除列表

removeDuplicate（人）;

Answer 2

我无法正确理解您的适配器。但我可以给你一个建议，因为我遇到了这个问题，我找到了一条出路。不确定它是否适用于您的问题，但您可以尝试：从ArrayList中删除项目后，您可以编写以下代码：

RequestAdapter.this.remove（的getItem（位置））;

此代码将从listView中删除已删除的项目。希望它会奏效。感谢。

如何通过自定义适配器删除元素后刷新listView？

2 个答案: