Question

我的列表视图项包含一个删除按钮，我在我的适配器中将其设置为从数据库中删除该项。现在，一旦完成，我如何刷新包含listView的片段以删除该项目？相关代码如下：

删除适配器中的项目功能：

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

            AlertDialog alertDialog = new AlertDialog.Builder(mContext).create();
            alertDialog.setTitle("Delete item");
            alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "yes",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {

                            FirebaseMethods firebaseMethods = new FirebaseMethods(mContext);
                            firebaseMethods.deleteHashtagFromDatabase(title);

                            dialog.dismiss();
                        }
                    });
            alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "no",
                    new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.dismiss();
                        }
                    });


                    alertDialog.show();


        }
    });

Listview在我的片段中设置如下：

private void setupListView(){

    Log.d(TAG, "setupListView: setting up list");
    final ArrayList<HashTag> hashTags = new ArrayList<>();
    myRef = FirebaseDatabase.getInstance().getReference();
    Query query = myRef.child(getString(R.string.dbname_user_hashtags))
            .child(FirebaseAuth.getInstance().getCurrentUser().getUid());
    query.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for(DataSnapshot singleSnapshot : dataSnapshot.getChildren()){


                if(singleSnapshot != null){
                    hashTags.add(0, singleSnapshot.getValue(HashTag.class));
                }

            }

            HashTagListViewAdapter adapter = new HashTagListViewAdapter(getActivity(), R.layout.layout_list_itemview, hashTags);
            hashtagListView.setAdapter(adapter);



        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

谢谢！

更新

现在我已将subItem上的OnClickListener从适配器传递到片段ListView OnItemClickListener，如下所示：

更新了适配器

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

            ((ListView) parent).performItemClick(v, position, 0);



        }
    });

更新了片段

hashtagListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, final int position, long id) {


            long viewId = view.getId();
            Log.d(TAG, "onItemClick: viewId is " + viewId);
            Log.d(TAG, "onItemClick: position is " + position);

            final HashTagListViewAdapter adapter = new HashTagListViewAdapter(getActivity(), R.layout.layout_list_itemview, hashTags);
            final HashTag hashTag = hashTags.get(position);
            final String title = hashTag.getTitle();
            Log.d(TAG, "onItemClick: title is " + title);


            if(viewId == R.id.deleteFromListBtn){

                AlertDialog alertDialog = new AlertDialog.Builder(getActivity()).create();
                alertDialog.setTitle("delete item");
                alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "yes",
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int which) {

                                FirebaseMethods firebaseMethods = new FirebaseMethods(getActivity());
                                firebaseMethods.deleteHashtagFromDatabase(title);
                                Log.d(TAG, "onClick: title is " + title);

                                // NEW PROBLEM HERE!
                                adapter.remove(hashTag);
                                Log.d(TAG, "onClick: removed hashtag is " + hashTag);
                                adapter.notifyDataSetChanged();

                                Log.d(TAG, "onItemClick: item removed from list.");

                                dialog.dismiss();
                            }
                        });
                alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "no",
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                dialog.dismiss();
                            }
                        });


                alertDialog.show();


            }
        }
    });

但现在问题是当我删除项目时，listView总是删除视图中的最后一项。但是，正确的项目已从数据库中删除，并且根据日志，此代码adapter.remove(hashTag)会抓取我打算删除的正确项目。

Answer 1

首先，你不应该刷新整个Fragment。坏习惯

刷新ListView，

首先从ArrayList中删除该项目（名为＆＃39; hashTags＆＃39;）。
只需致电YOUR_ADAPTER.notifyDataSetChanged()。

notifyDataSetChanged（）会自动从ListView删除项目。

Use of notifyDataSetChanged()

Answer 2

首先应该从数据库中删除该项，当成功来自数据库时，应该从ArrayList中删除该项，并且适配器应该通知ArratList中所做的更改。

从ArrayList表单适配器类中删除项目。

//postion is the location of item in the arraylist to be deleted.
dataSet.remove(position);

现在告知适配器有关ArrayList中的更改。应该调用Adapter类。

 notifyDataSetChanged();

ListView始终删除最后一项

2 个答案: