使用RecyclerView创建动态列表:
当我们创建一个RecyclerView时。适配器我们必须指定ViewHolder,它将绑定到适配器。
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private String[] mDataset;
public MyAdapter(String[] myDataset) {
mDataset = myDataset;
}
public static class ViewHolder extends RecyclerView.ViewHolder {
public TextView mTextView;
public ViewHolder(TextView v) {
super(v);
mTextView = v;
}
}
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.some_layout, parent, false);
//findViewById...
ViewHolder vh = new ViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
holder.mTextView.setText(mDataset[position]);
}
@Override
public int getItemCount() {
return mDataset.length;
}
}
有可能创建多个视图类型的RecyclerView吗?
比以往任何时候都简单,忘记ViewTypes。不建议在一个适配器中使用多个视图类型。这将使代码混乱,并打破单一责任原则,因为现在适配器需要处理逻辑来知道要填充哪个视图。
现在,想象一下在大型团队中工作,每个团队都必须在这些视图类型中的一种功能中工作。如果在不同视图类型中工作的所有团队都使用同一个适配器,那将是一团糟。这是使用ConcatAdapter解决的,其中隔离了适配器。逐个编码,然后将它们合并到一个视图中。
在recyclerview:1.2.0-alpha04中,您现在可以使用ConcatAdapter。
如果你需要一个具有不同viewTypes的视图,你可以为每个部分编写适配器,并使用ConcatAdapter将它们合并到一个recyclerview中。
ConcatAdapter
这张图片显示了一个recyclerview拥有的三种不同的视图类型,页眉,内容和页脚。
你只需要为每个section创建一个适配器,然后使用ConcatAdapter将它们合并到一个recyclerview中:
val firstAdapter: FirstAdapter = …
val secondAdapter: SecondAdapter = …
val thirdAdapter: ThirdAdapter = …
val concatAdapter = ConcatAdapter(firstAdapter, secondAdapter,
thirdAdapter)
recyclerView.adapter = concatAdapter
这就是你需要知道的。如果您想处理加载状态,例如在某些加载发生后删除最后一个适配器,您可以使用LoadState。
欲了解更多深入信息,请关注Florina Muntenescu的帖子https://medium.com/androiddevelopers/merge-adapters-sequentially-with-mergeadapter-294d2942127a
是的,这是可能的。
写一个通用的视图持有者:
public abstract class GenericViewHolder extends RecyclerView.ViewHolder
{
public GenericViewHolder(View itemView) {
super(itemView);
}
public abstract void setDataOnView(int position);
}
然后创建你的视图持有者,并让他们扩展GenericViewHolder。比如这个:
public class SectionViewHolder extends GenericViewHolder{
public final View mView;
public final TextView dividerTxtV;
public SectionViewHolder(View itemView) {
super(itemView);
mView = itemView;
dividerTxtV = (TextView) mView.findViewById(R.id.dividerTxtV);
}
@Override
public void setDataOnView(int position) {
try {
String title= sections.get(position);
if(title!= null)
this.dividerTxtV.setText(title);
}catch (Exception e){
new CustomError("Error!"+e.getMessage(), null, false, null, e);
}
}
}
然后是RecyclerView。适配器类看起来像这样:
public class MyClassRecyclerViewAdapter extends RecyclerView.Adapter<MyClassRecyclerViewAdapter.GenericViewHolder> {
@Override
public int getItemViewType(int position) {
// depends on your problem
switch (position) {
case : return VIEW_TYPE1;
case : return VIEW_TYPE2;
...
}
}
@Override
public GenericViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view;
if(viewType == VIEW_TYPE1){
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout1, parent, false);
return new SectionViewHolder(view);
}else if( viewType == VIEW_TYPE2){
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout2, parent, false);
return new OtherViewHolder(view);
}
// Cont. other view holders ...
return null;
}
@Override
public void onBindViewHolder(GenericViewHolder holder, int position) {
holder.setDataOnView(position);
}
是的,这是可能的。只需实现getItemViewType(),并照顾onCreateViewHolder()中的viewType参数。
所以你可以这样做:
public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
class ViewHolder0 extends RecyclerView.ViewHolder {
...
public ViewHolder0(View itemView){
...
}
}
class ViewHolder2 extends RecyclerView.ViewHolder {
...
public ViewHolder2(View itemView){
...
}
@Override
public int getItemViewType(int position) {
// Just as an example, return 0 or 2 depending on position
// Note that unlike in ListView adapters, types don't have to be contiguous
return position % 2 * 2;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
switch (viewType) {
case 0: return new ViewHolder0(...);
case 2: return new ViewHolder2(...);
...
}
}
@Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int position) {
switch (holder.getItemViewType()) {
case 0:
ViewHolder0 viewHolder0 = (ViewHolder0)holder;
...
break;
case 2:
ViewHolder2 viewHolder2 = (ViewHolder2)holder;
...
break;
}
}
}
这是非常简单直接的。
只需在适配器中重写getItemViewType()方法。根据数据返回不同的itemViewType值。例如,考虑一个Person类型的对象,其成员为male,如果isMale为真,则返回1,isMale为假,则在getItemViewType()方法中返回2。
现在来到createViewHolder (ViewGroup parent, int viewType),在不同的viewType的基础上,你可以膨胀不同的布局文件。像下面这样:
if (viewType == 1){
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.male, parent, false);
return new AdapterMaleViewHolder(view);
}
else{
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.female, parent, false);
return new AdapterFemaleViewHolder(view);
}
在onBindViewHolder (VH holder,int position)检查holder是AdapterFemaleViewHolder或AdapterMaleViewHolder的实例,并相应地分配值。
ViewHolder可能是这样的
class AdapterMaleViewHolder extends RecyclerView.ViewHolder {
...
public AdapterMaleViewHolder(View itemView){
...
}
}
class AdapterFemaleViewHolder extends RecyclerView.ViewHolder {
...
public AdapterFemaleViewHolder(View itemView){
...
}
}
你可以使用这个图书馆:https://github.com/vivchar/RendererRecyclerViewAdapter
mRecyclerViewAdapter = new RendererRecyclerViewAdapter(); /* Included from library */
mRecyclerViewAdapter.registerRenderer(new SomeViewRenderer(SomeModel.TYPE, this));
mRecyclerViewAdapter.registerRenderer(...); /* You can use several types of cells */
对于每一个项目,你应该实现一个ViewRenderer, ViewHolder, SomeModel:
ViewHolder -它是回收器视图的一个简单视图持有者。
SomeModel -它是你的模型与ItemModel接口
public class SomeViewRenderer extends ViewRenderer<SomeModel, SomeViewHolder> {
public SomeViewRenderer(final int type, final Context context) {
super(type, context);
}
@Override
public void bindView(@NonNull final SomeModel model, @NonNull final SomeViewHolder holder) {
holder.mTitle.setText(model.getTitle());
}
@NonNull
@Override
public SomeViewHolder createViewHolder(@Nullable final ViewGroup parent) {
return new SomeViewHolder(LayoutInflater.from(getContext()).inflate(R.layout.some_item, parent, false));
}
}
有关更多详细信息,您可以查看文档。