ExpandableListView Only Last 上的自定义指标正在发生变化

Question

我正在尝试使用自定义指标实现 ExpandableListView。该列表有两组，每组有 3 个孩子。

问题是当我点击 group1 时，指示器没有改变，但如果我点击 group2，指示器工作正常。

我不知道怎么回事。

我也想了解更多关于getTag()和setTag()的信息。如何访问特定的 GroupView 或 ChildView.

@Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.group_view, null);
            groupname = (TextView) convertView.findViewById(R.id.groupNamesTV);
             imageView = (ImageView) convertView.findViewById(R.id.indicator);
            convertView.setTag(new ViewHolderForGroup(groupname , imageView));
            group = (ViewHolderForGroup) convertView.getTag();

        }
        if(isExpanded)
        {
            imageView.setImageResource(R.mipmap.down);


        }else {
            imageView.setImageResource(R.mipmap.right);
        }

        group.txtView.setText(groupnames.get(groupPosition));
        return convertView;
    }

Answer 1

你错过了 convertView 不为 null 的情况，你需要在这种情况下分配 imageView :)

@Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.group_view, null);
            groupname = (TextView) convertView.findViewById(R.id.groupNamesTV);
             imageView = (ImageView) convertView.findViewById(R.id.indicator);
            convertView.setTag(new ViewHolderForGroup(groupname , imageView));
            group = (ViewHolderForGroup) convertView.getTag();

        } else {

            // we have a view previously created, our stuff is in the TAG
            group = (ViewHolderForGroup) convertView.getTag();
            imageView = group.imageView; // or whatever its name is             
        }




        if(isExpanded)
        {
            imageView.setImageResource(R.mipmap.down);


        }else {
            imageView.setImageResource(R.mipmap.right);
        }

        group.txtView.setText(groupnames.get(groupPosition));
        return convertView;
    }

这里的关键点是，convertview==null 是最坏的情况，此时还没有创建视图。然后，您正确地创建了所有内容并将其存储在 TAG 中。 标签就像一个盒子，您可以在其中存放任何您想要的东西。

以后系统需要另外一个视图时，convertView不会为null，然后就是访问TAG中之前存储的东西，恢复imageView。

您可以像这样进一步优化您的例程：

 @Override
            public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

                if (convertView == null) {

                    // all this is very slow, that's why we only do it when
                    // convertView is null, because it's common to all items.
                    // once a view is created, we will reuse this to show another row

                    convertView = inflater.inflate(R.layout.group_view, null);
                    TextView textGroup = (TextView) convertView.findViewById(R.id.groupNamesTV);
                    ImageView imgGroup = (ImageView) convertView.findViewById(R.id.indicator);
                    convertView.setTag(new ViewHolderForGroup(textGroup, imgGroup));

                } 

                // regardless of convertView is newly created or recycled, the TAG will now always contain the ViewHolder
                ViewHolderForGroup groupHolder = (ViewHolderForGroup) convertView.getTag();

                groupHolder.imageView.setImageResource(isExpanded?R.mipmap.down:R.mipmap.right);
                groupHolder.txtView.setText(groupnames.get(groupPosition));
                return convertView;
            }

你看我已经将 imageView、group 和 groupname 切换为局部变量而不是成员：这样你就不可能运行像以前一样出错。

ExpandableListView Only Last 上的自定义指标正在发生变化

Custom Indicator on ExpandableListView Only Last is changing

java

android

expandablelistview