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?
我推荐汉内斯·多夫曼的这个图书馆。它将所有与特定视图类型相关的逻辑封装在一个名为“AdapterDelegate”的单独对象中。
https://github.com/sockeqwe/AdapterDelegates
public class CatAdapterDelegate extends AdapterDelegate<List<Animal>> {
private LayoutInflater inflater;
public CatAdapterDelegate(Activity activity) {
inflater = activity.getLayoutInflater();
}
@Override public boolean isForViewType(@NonNull List<Animal> items, int position) {
return items.get(position) instanceof Cat;
}
@NonNull @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent) {
return new CatViewHolder(inflater.inflate(R.layout.item_cat, parent, false));
}
@Override public void onBindViewHolder(@NonNull List<Animal> items, int position,
@NonNull RecyclerView.ViewHolder holder, @Nullable List<Object> payloads) {
CatViewHolder vh = (CatViewHolder) holder;
Cat cat = (Cat) items.get(position);
vh.name.setText(cat.getName());
}
static class CatViewHolder extends RecyclerView.ViewHolder {
public TextView name;
public CatViewHolder(View itemView) {
super(itemView);
name = (TextView) itemView.findViewById(R.id.name);
}
}
}
public class AnimalAdapter extends ListDelegationAdapter<List<Animal>> {
public AnimalAdapter(Activity activity, List<Animal> items) {
// DelegatesManager is a protected Field in ListDelegationAdapter
delegatesManager.addDelegate(new CatAdapterDelegate(activity))
.addDelegate(new DogAdapterDelegate(activity))
.addDelegate(new GeckoAdapterDelegate(activity))
.addDelegate(23, new SnakeAdapterDelegate(activity));
// Set the items from super class.
setItems(items);
}
}
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){
...
}
}
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);
}
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。
