取消选择并向下滚动后，列表视图中的复选框被选中。

Posted 2023-05-07

【中文标题】取消选择并向下滚动后，列表视图中的复选框被选中。

【英文标题】：Checkbox in listview getting selected after unselecting it and scrolling down.

【发布时间】：2015-11-30 10:10:14

【问题描述】：

我知道有人提出了多个与我的问题类似的问题，但尚未解决我的特定问题。

我有一个 BaseAdapter，它准备了一个带有复选框的列表。

这里是适配器的相关代码——

 @Override
    public View getView(final int position, View convertView, ViewGroup parent) 
        selectedFolderIds = new ArrayList<>();
        selectedFolderNames = new ArrayList<>();
        selectedFolderParentIds = new ArrayList<>();
        deselectedFolderIds = new ArrayList<>();

        final FolderStructureDataModel folderDetails = (FolderStructureDataModel) getItem(position);

        final ViewHolder holder;
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        if(convertView == null) 
            convertView = inflater.inflate(R.layout.folder_structure_list_item_template,
                    parent, false);
            holder = new ViewHolder();
            holder.folderListLayout = (RelativeLayout) convertView.findViewById(R.id.folder_list_layout);
            holder.childFoldersIndicator = (ImageView)
                    convertView.findViewById(R.id.child_folders_indicator);
            holder.selectionCheckBox = (CheckBox) convertView.findViewById(R.id.checkbox);

            convertView.setTag(holder);
         else 
            holder = (ViewHolder) convertView.getTag();
            holder.selectionCheckBox.setOnCheckedChangeListener(null);
            holder.selectionCheckBox.setOnClickListener(null);
        

        /**
         * Attach the listeners to the checkboxes.
         */
        holder.selectionCheckBox.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                CheckBox cb = (CheckBox) view;
                if (cb.isChecked()) 
                    selectedFolderIds.add(HelperFunctions.EncodeString(folderDetails.ID));
                    selectedFolderNames.add(HelperFunctions.EncodeString(folderDetails.DisplayName));
                    selectedFolderParentIds.add(HelperFunctions.EncodeString(folderDetails.ParentFolderID));

                    SelectedFolderListener selectedFolderListener =
                            (SelectedFolderListener) context;
                    selectedFolderListener.getSelectedFoldersArrayList(selectedFolderIds,
                            selectedFolderNames, selectedFolderParentIds);

                    Log.i("Test : " + folderDetails.DisplayName + " at position " +
                            String.valueOf(position), "Set to " +
                            String.valueOf(checkboxStatus.get(position))
                            + " From onClickListener");
                 else 
                    selectedFolderIds.remove(HelperFunctions.EncodeString(folderDetails.ID));
                    selectedFolderNames.remove(HelperFunctions
                            .EncodeString(folderDetails.DisplayName));
                    selectedFolderParentIds.remove(HelperFunctions
                            .EncodeString(folderDetails.ParentFolderID));
                    deselectedFolderIds.add(HelperFunctions.EncodeString(folderDetails.ID));

                    UnselectedFolderListener unselectedFolderListener =
                            (UnselectedFolderListener) context;
                    unselectedFolderListener.getDeselectedFolderArrayList(deselectedFolderIds);

                    Log.i("Test : " + folderDetails.DisplayName + " at position " +
                            String.valueOf(position), "Set to " +
                            String.valueOf(checkboxStatus.get(position))
                            + " From onClickListener");
                
            
        );

        holder.selectionCheckBox.setOnCheckedChangeListener
                (new CompoundButton.OnCheckedChangeListener() 

                    @Override
                    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) 

                        if (((buttonView).isChecked()) && isChecked) 
                            checkboxStatus.set(position, true);
                            Log.i("Test : " + folderDetails.DisplayName + " at position " +
                                    String.valueOf(position), "Set to " +
                                    String.valueOf(checkboxStatus.get(position))
                                    + " From onCheckChangedListener");
                         else 
                            checkboxStatus.set(position, false);
                            Log.i("Test : " + folderDetails.DisplayName + " at position " +
                                    String.valueOf(position), "Set to " +
                                    String.valueOf(checkboxStatus.get(position))
                                    + " From onCheckChangedListener");
                        
                    
                );

        //Populate the data
        holder.selectionCheckBox.setText(String.valueOf(folderDetails.DisplayName));

        if(Integer.valueOf(folderDetails.ChildFolderCount) == 0) 
            holder.childFoldersIndicator.setVisibility(View.GONE);
            holder.folderListLayout.setFocusable(true);
            holder.folderListLayout.setClickable(true);
         else 
            holder.childFoldersIndicator.setVisibility(View.VISIBLE);
            holder.folderListLayout.setFocusable(false);
            holder.folderListLayout.setClickable(false);
        

        /**
         * Set the checkbox as per the service reply (status in the server)
         */
        if(Boolean.valueOf(folderDetails.IsAlreadySelected)) 
            holder.selectionCheckBox.setChecked(true);
            Log.i("Test : " + folderDetails.DisplayName + " at position " +
                    String.valueOf(position), "Set to " +
                    String.valueOf(holder.selectionCheckBox.isChecked()) + " From folderDetails");
         else 
            holder.selectionCheckBox.setChecked(false);
            Log.i("Test : " + folderDetails.DisplayName + " at position " +
                    String.valueOf(position), "Set to " +
                    String.valueOf(holder.selectionCheckBox.isChecked()) + " From folderDetails");
        

        /**
         * Set the checkbox as per the values maintained in the checkboxStatus ArrayList
         */
        if(checkboxStatus.get(position)) 
            holder.selectionCheckBox.setChecked(true);
            Log.i("Test : " + folderDetails.DisplayName + " at position " +
                    String.valueOf(position), "Set to " +
                    String.valueOf(holder.selectionCheckBox.isChecked()) + " From checkBoxStatus");
         else 
            holder.selectionCheckBox.setChecked(false);
            Log.i("Test : " + folderDetails.DisplayName + " at position " +
                    String.valueOf(position), "Set to " +
                    String.valueOf(holder.selectionCheckBox.isChecked()) + " From checkBoxStatus");
        

        return convertView;
    

我有一个ArrayListcheckboxStatus，它维护每个位置复选框的状态。

我面临的问题是，如果一个复选框已被选中（根据“folderDetails.IsAlreadySelected”的值），我取消选中它并向下滚动然后向上滚动，该复选框将再次被选中。特殊的部分是在相反的情况下不会发生这种情况 - 如果未选中复选框，我选中它并向下滚动然后再次向上滚动；状态保持为选中状态。

适配器可能有什么问题？

【参考方案1】：

要解决您的问题，请执行以下操作：

if(convertView == null) 
        convertView = inflater.inflate(R.layout.folder_structure_list_item_template,
                parent, false);
        holder = new ViewHolder();
        holder.folderListLayout = (RelativeLayout) convertView.findViewById(R.id.folder_list_layout);
        holder.childFoldersIndicator = (ImageView)
                convertView.findViewById(R.id.child_folders_indicator);
        holder.selectionCheckBox = (CheckBox) convertView.findViewById(R.id.checkbox);
  // Add this line, set tag on your checkbox.
 holder.selectionCheckBox .setTag(holder);
        convertView.setTag(holder);
    

现在在 clicklistner 上，

 holder.selectionCheckBox.setOnClickListener(new View.OnClickListener() 
        @Override
        public void onClick(View view) 
         // add this line,declare holder_new as an instance of ViewHolder
        holder_new= (ViewHolder) view.getTag();
            // rest is your code what you have already written
    );

现在在 onclick 之后，无论您使用 holder 访问 selectionCheckBox 的任何位置，都将其更改为 holder_new。

holder.selectionCheckBox.setChecked(true); 将其更改为 holder_new.selectionCheckBox.setChecked(true);

【讨论】：

holder_new== (ViewHolder) view.getTag(); 我猜你的意思是holder_new = (ViewHolder) view.getTag();，对吧？另外，我在哪里声明holder_view？

yup.. 输入错误：P 在声明“持有人”的同一位置声明它。由您决定，您也可以在类级别声明它。

我必须使它成为全局的，否则我会得到variable accessed from inner class needs to be declared final 错误。我通过上述更改尝试了您的实现，但由于 holder_new.selectionCheckBox.setChecked(true);

处的 NullPointerException，活动正在崩溃

//添加这一行，将 holder_new 声明为 ViewHolder 的一个实例 holder_new= (ViewHolder) view.getTag();你没有初始化 holder_new 吗？

我做到了。我创建了一个全局变量holder_new，在适配器构造函数中使用viewHolder = new ViewHolder(); 启动它，然后按照您上面所说的进行操作。我仍然得到一个 NPE。