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ELIMINATE RECYCLERVIEW
BOILERPLATES
͍͍ @shaunkawano
גࣜձࣾτϧς / Android Developer
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Shohei Kawano
@shaunkawano
Android Developer at Torte, Inc.
About Me
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Let’s talk about RecyclerView
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When you use RecyclerView,
you need to implement
RecyclerView.Adapter
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RecyclerView.Adapter basic
methods
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RecyclerView.Adapter basic methods
void onBindViewHolder(VH holder, int position)
VH onCreateViewHolder(ViewGroup parent, int
viewType)
int getItemViewType(int position)
int getItemCount()
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RecyclerView.Adapter basic methods
void onBindViewHolder(VH holder, int position)
VH onCreateViewHolder(ViewGroup parent, int
viewType)
int getItemViewType(int position)
int getItemCount()
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Let’s assume we have
R.layout.id as our view type.
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onCreateViewHolder
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@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int
viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (viewType) {
case R.layout.row_taro:
View taroView = inflater.inflate(R.layout.row_taro, parent, false);
return new TaroViewHolder(taroView);
case R.layout.row_shiro:
View shiroView = inflater.inflate(R.layout.row_shiro, parent, false);
return new ShiroViewHolder(shiroView);
case R.layout.row_leona:
View leonaView = inflater.inflate(R.layout.row_leona, parent, false);
return new LeonaViewHolder(leonaView);
default:
throw new IllegalArgumentException(“error message here.”);
}
}
onCreateViewHolder
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onBindViewHolder
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onBindViewHolder
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int
position) {
int viewType = getItemViewType(position);
switch (viewType) {
case R.layout.row_taro:
onBindTaroViewHolder((TaroViewHolder) holder, position);
break;
case R.layout.row_shiro:
onBindShiroViewHolder((ShiroViewHolder) holder, position);
break;
case R.layout.row_leona:
onBindLeonaViewHolder((LeonaViewHolder) holder, position);
break;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
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@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int
position) {
int viewType = getItemViewType(position);
switch (viewType) {
case R.layout.row_taro:
onBindTaroViewHolder((TaroViewHolder) holder, position);
break;
case R.layout.row_shiro:
onBindShiroViewHolder((ShiroViewHolder) holder, position);
break;
case R.layout.row_leona:
onBindLeonaViewHolder((LeonaViewHolder) holder, position);
break;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
onBindViewHolder
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@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int
position) {
int viewType = getItemViewType(position);
switch (viewType) {
case R.layout.row_taro:
onBindTaroViewHolder((TaroViewHolder) holder, position);
break;
case R.layout.row_shiro:
onBindShiroViewHolder((ShiroViewHolder) holder, position);
break;
case R.layout.row_leona:
onBindLeonaViewHolder((LeonaViewHolder) holder, position);
break;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
onBindViewHolder
8FOFFEUPDBTUʜ
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getItemViewType
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getItemViewType
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Let’s see the overview.
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RecyclerView.Adapter Overview
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
int viewType = getItemViewType(position);
switch (viewType) {
case R.layout.row_taro:
onBindTaroViewHolder((TaroViewHolder) holder, position);
break;
case R.layout.row_shiro:
onBindShiroViewHolder((ShiroViewHolder) holder, position);
break;
case R.layout.row_leona:
onBindLeonaViewHolder((LeonaViewHolder) holder, position);
break;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (viewType) {
case R.layout.row_taro:
View taroView = inflater.inflate(R.layout.row_taro, parent, false);
return new TaroViewHolder(taroView);
case R.layout.row_shiro:
View shiroView = inflater.inflate(R.layout.row_shiro, parent, false);
return new ShiroViewHolder(shiroView);
case R.layout.row_leona:
View leonaView = inflater.inflate(R.layout.row_leona, parent, false);
return new LeonaViewHolder(leonaView);
default:
throw new IllegalArgumentException(“error message here.”);
}
}
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RecyclerView.Adapter Overview
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
int viewType = getItemViewType(position);
switch (viewType) {
case R.layout.row_taro:
onBindTaroViewHolder((TaroViewHolder) holder, position);
break;
case R.layout.row_shiro:
onBindShiroViewHolder((ShiroViewHolder) holder, position);
break;
case R.layout.row_leona:
onBindLeonaViewHolder((LeonaViewHolder) holder, position);
break;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (viewType) {
case R.layout.row_taro:
View taroView = inflater.inflate(R.layout.row_taro, parent, false);
return new TaroViewHolder(taroView);
case R.layout.row_shiro:
View shiroView = inflater.inflate(R.layout.row_shiro, parent, false);
return new ShiroViewHolder(shiroView);
case R.layout.row_leona:
View leonaView = inflater.inflate(R.layout.row_leona, parent, false);
return new LeonaViewHolder(leonaView);
default:
throw new IllegalArgumentException(“error message here.”);
}
}
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RecyclerView.Adapter Overview
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
int viewType = getItemViewType(position);
switch (viewType) {
case R.layout.row_taro:
onBindTaroViewHolder((TaroViewHolder) holder, position);
break;
case R.layout.row_shiro:
onBindShiroViewHolder((ShiroViewHolder) holder, position);
break;
case R.layout.row_leona:
onBindLeonaViewHolder((LeonaViewHolder) holder, position);
break;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
switch (viewType) {
case R.layout.row_taro:
View taroView = inflater.inflate(R.layout.row_taro, parent, false);
return new TaroViewHolder(taroView);
case R.layout.row_shiro:
View shiroView = inflater.inflate(R.layout.row_shiro, parent, false);
return new ShiroViewHolder(shiroView);
case R.layout.row_leona:
View leonaView = inflater.inflate(R.layout.row_leona, parent, false);
return new LeonaViewHolder(leonaView);
default:
throw new IllegalArgumentException(“error message here.”);
}
}
#PJMFSQMBUFTʜ
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RecyclerView Boilerplates
void onBindViewHolder(VH holder, int position)
VH onCreateViewHolder(ViewGroup parent, int
viewType)
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ɾ0CUBJOWJFX5ZQFGSPNQPTJUJPO
ɾ$BTU7JFX)PMEFSUPDVTUPN7JFX)PMEFSCBTFEPOQPTJUJPO
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YES WE WANT TO ELIMINATE
THEM.
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LET’S GENERATE THEM
INSTEAD OF WRITING THEM.
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PREREQUISITES
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1. Implement getItemViewType
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@Override
public int getItemViewType(int position) {
switch (CatType.of(position)) {
case TARO:
return R.layout.row_taro;
case SHIRO:
return R.layout.row_shiro;
case LEONA:
return R.layout.row_leona;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
Implement RecyclerView.Adapter#getItemViewType()
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@Override
public int getItemViewType(int position) {
switch (CatType.of(position)) {
case TARO:
return R.layout.row_taro;
case SHIRO:
return R.layout.row_shiro;
case LEONA:
return R.layout.row_leona;
default:
throw new IllegalArgumentException(“Some message.”);
}
}
Implement RecyclerView.Adapter#getItemViewType()
Return R.layout.id as view type
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2. Add annotations
@AdapterBinding
@ViewHolder
@OnBind
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@AdapterBinding
public class CatAdapter extends RecyclerView.Adapter {
…
}
@ViewHolder(layout = R.layout.row_title)
static class TitleViewHolder extends RecyclerView.ViewHolder {
TitleViewHolder(View itemView) {
super(itemView);
}
@OnBind
void onBind() {
// bind layouts
}
…
Add @AdapterBinding ,@ViewHolder, @OnBind (optional) annotations
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@AdapterBinding
public class CatAdapter extends RecyclerView.Adapter {
…
}
@ViewHolder(layout = R.layout.row_title)
static class TitleViewHolder extends RecyclerView.ViewHolder {
TitleViewHolder(View itemView) {
super(itemView);
}
@OnBind
void onBind() {
// bind layouts
}
…
Add @AdapterBinding ,@ViewHolder, @OnBind (optional) annotations
Add on RecyclerView.Adapter
Add on RecyclerView.ViewHolder
Add on inner methods within RecyclerView.ViewHolder
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3. Rebuild Project
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4. Call generated methods
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Call static methods within generated class
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position)
{
CatAdapterViewHolderBinding.bindViewHolder(this, holder, position);
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int
viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
return CatAdapterViewHolderBinding.createViewHolder(inflater, parent,
viewType);
}
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Call static methods within generated class
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position)
{
CatAdapterViewHolderBinding.bindViewHolder(this, holder, position);
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int
viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
return CatAdapterViewHolderBinding.createViewHolder(inflater, parent,
viewType);
}
Adapter໊ʴViewHolderBinding.bindViewHolder
Adapter໊ʴViewHolderBinding.bindViewHolder.createViewHolder
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Let’s take a look at generated
source codes.
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class CatAdapterViewHolderBinding {
public static ViewHolder createViewHolder(LayoutInflater inflater, ViewGroup parent,
int viewType) {
switch (viewType) {
case 2130968636:
View TaroViewHolderView = inflater.inflate(2130968636, parent, false);
return new CatAdapter.TaroViewHolder(TaroViewHolderView);
case 2130968635:
View ShiroViewHolderView = inflater.inflate(2130968635, parent, false);
return new CatAdapter.ShiroViewHolder(ShiroViewHolderView);
case 2130968634:
View LeonaViewHolderView = inflater.inflate(2130968634, parent, false);
return new CatAdapter.LeonaViewHolder(LeonaViewHolderView);
case 2130968637:
View TitleViewHolderView = inflater.inflate(2130968637, parent, false);
return new CatAdapter.TitleViewHolder(TitleViewHolderView);
default:
throw new IllegalArgumentException(String.format(Locale.US, "Illegal viewType(%d)
passed to CatAdapter.", viewType));
}
}
Generated method: createViewHolder
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Generated method: bindViewHolder
public static void bindViewHolder(Adapter adapter, ViewHolder holder, int position) {
int viewType = adapter.getItemViewType(position);
switch (viewType) {
case 2130968636:
((CatAdapter.TaroViewHolder) holder).onBind();
break;
case 2130968635:
((CatAdapter.ShiroViewHolder) holder).onBind();
break;
case 2130968634:
((CatAdapter.LeonaViewHolder) holder).onBind(position);
break;
case 2130968637:
((CatAdapter.TitleViewHolder) holder).onBind();
break;
default:
throw new IllegalArgumentException(String.format(Locale.US, "Illegal
viewType(%d) passed to CatAdapter.", viewType));
}
}
}
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ViewHolderBinding
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Conclusion
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ɾGenerating codes using Annotation Processor
is fun!
ɾWe’ll keep using RecyclerView for sure, so
ɾLet us write less to do more!
·ͱΊ
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THANK YOU !
͍͍ @shaunkawano
גࣜձࣾτϧς / Android Developer