[英]Android data binding with custom adapter
我正在尝试将Android 的数据绑定功能与自定义适配器和 ListView 一起使用。 我无法覆盖自定义适配器的getView
方法:
public class ChecksAdapter extends ArrayAdapter<Check> {
public ChecksAdapter(Context context, ObservableList<Check> checks) {
super(context, R.layout.check, checks);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
CheckBinding binding = DataBindingUtil.inflate(
LayoutInflater.from(getContext()),
R.layout.check, parent, false);
binding.setCheck(this.getItem(position));
// Return what?
}
}
所以我的问题是:
View
元素? 或者换句话说,如何将对象绑定到膨胀/转换的视图?convertView
?以下是指南中对 ListViews 的唯一参考:
如果您在 ListView 或 RecyclerView 适配器中使用数据绑定项,您可能更喜欢使用:
ListItemBinding binding = ListItemBinding.inflate(layoutInflater, viewGroup, false); //or ListItemBinding binding = DataBindingUtil.inflate(layoutInflater, R.layout.list_item, viewGroup, false);
您应该执行以下操作以平滑滚动..
@Override
public View getView(int position, View convertView, ViewGroup parent) {
CheckBinding binding;
if(convertView == null) {
binding = DataBindingUtil.inflate(
LayoutInflater.from(getContext()),
R.layout.check, parent, false);
convertView = binding.getRoot();
}
else {
binding = (CheckBinding) convertView.getTag();
}
binding.setCheck(this.getItem(position));
convertView.setTag(binding);
return convertView;
}
根据这个,你应该返回binding.getRoot()
View getRoot ()
返回与 Binding 关联的布局文件中最外层的 View。 如果此绑定用于合并布局文件,这将返回合并标记中的第一个根。
为了完成这里是 kotlin 变体:
val binding = convertView?.tag as? CheckBinding ?: CheckBinding.inflate(layoutInflater, parent, false)
binding.check = this.getItem(position)
binding.root.tag = binding
return binding.root
使用生成的 Binding 类而不是 DataBindingUtil 类。 请参阅文档。
如果您在
Fragment
、ListView
或RecyclerView
适配器中使用数据绑定项,您可能更喜欢使用绑定类的inflate()
方法
binding = CheckBinding.inflate(this, parent, false);
binding = DataBindingUtil.inflate(
LayoutInflater.from(getContext()),
R.layout.check, parent, false);
其他代码将与@sergi 相同
@Override
public View getView(int position, View convertView, ViewGroup parent) {
CheckBinding binding;
if(convertView == null) {
binding = CheckBinding.inflate(this, parent, false);
convertView = binding.getRoot();
}
else {
binding = (CheckBinding) convertView.getTag();
}
binding.setCheck(this.getItem(position));
convertView.setTag(binding);
return convertView;
}
ItemTickFilterBinding mFilterBinding;
if (convertView==null) {
mFilterBinding= DataBindingUtil.inflate(
LayoutInflater.from(mContext),
R.layout.item_tick_filter, parent, false);
convertView.setTag(mFilterBinding);
}
else {
mFilterBinding=(ItemTickFilterBinding)convertView.getTag();
}
DataBindingUtil 会将 ViewDataBinding 对象保存到 view.tag,以便您稍后可以通过 DataBindingUtil.getBinding(convertView) 检索它
@Override
public View getView(int position, View convertView, ViewGroup parent) {
return getViewForResource(mResourceId, position, convertView, parent);
}
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
return getViewForResource(mDropDownResourceId, position, convertView, parent);
}
public View getViewForResource(int resourceId, int position, View convertView, ViewGroup parent) {
final ViewDataBinding binding = (convertView != null) ? DataBindingUtil.getBinding(convertView) : DataBindingUtil.inflate(mLayoutInflater, resourceId, parent, false);
binding.setVariable(BR.viewModel, getItem(position));
return binding.getRoot();
}
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