如何在不替换项目的情况下在一个 Recyclerview 中添加两个自定义行，它显示两个自定义行但它删除了项目编号 1 我该如何解决？
代码
public class MessagesAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private Context context;
private List<MessagesEntity> messagesEntityList;
private AppDatabase appDatabase;
private Typeface typeface;
public MessagesAdapter(Context context, List<MessagesEntity> messagesEntityList) {
this.context = context;
this.messagesEntityList = messagesEntityList;
appDatabase = Room.databaseBuilder(context, AppDatabase.class, "app_database").allowMainThreadQueries().build();
typeface = Typeface.createFromAsset(context.getAssets(), "MainFont.ttf");
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
if (viewType == 100) {
return new ViewHolder1(LayoutInflater.from(parent.getContext()).inflate(R.layout.row_short_description, parent, false));
} else {
return new ViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.row_message, parent, false));
}
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
if (getItemViewType(position) == 100) {
ViewHolder1 viewHolder1 = (ViewHolder1) holder;
viewHolder1.txtShortDescription.setTypeface(typeface);
viewHolder1.txtShortDescription.setText(MessagesActivity.description);
} else {
ViewHolder viewHolder = (ViewHolder) holder;
viewHolder.txtMessage.setTypeface(typeface);
if (position % 2 == 0) {
viewHolder.linearLayout1.setBackgroundColor(context.getResources().getColor(R.color.m_a_1_row_background_1));
viewHolder.txtMessage.setTextColor(context.getResources().getColor(R.color.m_a_1_row_category_name_2));
} else if (position % 2 == 1) {
viewHolder.linearLayout1.setBackgroundColor(context.getResources().getColor(R.color.m_a_1_row_background_2));
viewHolder.txtMessage.setTextColor(context.getResources().getColor(R.color.m_a_1_row_category_name_1));
}
if (appDatabase.favoriteDao().getMessage(messagesEntityList.get(position).getId()).size() == 0) {
viewHolder.imgFavorite.setColorFilter(context.getResources().getColor(R.color.white), PorterDuff.Mode.SRC_IN);
} else {
viewHolder.imgFavorite.setColorFilter(context.getResources().getColor(R.color.cinnabar), PorterDuff.Mode.SRC_IN);
}
viewHolder.txtMessage.setText(messagesEntityList.get(position).getMessage());
}
}
@Override
public int getItemCount() {
return messagesEntityList.size();
}
@Override
public int getItemViewType(int position) {
if (position == 0) {
return 100;
} else {
return super.getItemViewType(position);
}
}
class ViewHolder extends RecyclerView.ViewHolder {
@BindView(R.id.linear_layout_1)
LinearLayout linearLayout1;
@BindView(R.id.txt_message)
TextView txtMessage;
@BindView(R.id.img_favorite)
ImageView imgFavorite;
@BindView(R.id.img_copy)
ImageView imgCopy;
@BindView(R.id.img_share)
ImageView imgShare;
ViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
@OnClick({R.id.img_share, R.id.img_copy, R.id.img_favorite})
void onClick(View view) {
switch (view.getId()) {
case R.id.img_share:
Intent intent = new Intent(Intent.ACTION_SEND);
intent.putExtra(Intent.EXTRA_TEXT, messagesEntityList.get(getAdapterPosition()).getMessage());
intent.setType("text/plain");
context.startActivity(Intent.createChooser(intent, ""));
break;
case R.id.img_copy:
ClipboardManager clipboard = (ClipboardManager) context.getSystemService(CLIPBOARD_SERVICE);
clipboard.setPrimaryClip(ClipData.newPlainText("copied", messagesEntityList.get(getAdapterPosition()).getMessage()));
CustomToast.show(context, context.getResources().getString(R.string.copied));
break;
case R.id.img_favorite:
if (appDatabase.favoriteDao().getMessage(messagesEntityList.get(getAdapterPosition()).getId()).size() == 0) {
FavoriteEntity favoriteEntity = new FavoriteEntity();
favoriteEntity.setId(messagesEntityList.get(getAdapterPosition()).getId());
favoriteEntity.setMessage(messagesEntityList.get(getAdapterPosition()).getMessage());
favoriteEntity.setCategoryName(messagesEntityList.get(getAdapterPosition()).getCategoryName());
appDatabase.favoriteDao().addMessage(favoriteEntity);
CustomToast.show(context, context.getResources().getString(R.string.added_to_favorite));
imgFavorite.setColorFilter(context.getResources().getColor(R.color.cinnabar), PorterDuff.Mode.SRC_IN);
} else {
appDatabase.favoriteDao().deleteMessage(messagesEntityList.get(getAdapterPosition()).getId());
CustomToast.show(context, context.getResources().getString(R.string.removed_from_favorite));
imgFavorite.setColorFilter(context.getResources().getColor(R.color.white), PorterDuff.Mode.SRC_IN);
}
break;
}
}
}
class ViewHolder1 extends RecyclerView.ViewHolder {
@BindView(R.id.linear_layout_1)
LinearLayout linearLayout1;
@BindView(R.id.txt_short_description)
TextView txtShortDescription;
ViewHolder1(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
}
}
我想先显示 row_short_description 行，然后显示所有项目而不删除任何数据................................................ ..................................................... ..................................................... .
最佳答案
容易的事情是修复索引。您现在有 messagesEntityList.size() + 1 个项目，所以:
@Override
public int getItemCount() {
return messagesEntityList.size() + 1;
}
但是，您还必须修复 onBindViewHolder 中的索引，但这容易出错。适配器不应该知道所有这些，您应该只向它提供数据，然后它会绑定(bind)到 View 持有者。
更好的解决方案是创建两个类，它们从同一个接口(interface)扩展:
// Base message for the adapter
interface BaseMessage {}
// Message for the adapter
class Message implements BaseMessage {
private int id;
private String message;
private String categoryName;
Message(int id, String message, String categoryName) {
this.id = id;
this.message = message;
this.categoryName = categoryName;
}
public int getId() {
return id;
}
public String getMessage() {
return message;
}
public String getCategoryName() {
return categoryName;
}
}
// Message description for the adapter
class MessageDescription implements BaseMessage { }
然后是您的适配器(您需要在需要时将 BaseMessage 从列表转换为 Message):
// BaseMessage: Message, MessageDescription
// Message -- MessageViewHolder
// MessageDescription -- DescriptionViewHolder
public class MessagesAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int VIEW_TYPE_MESSAGE = 0;
private static final int VIEW_TYPE_SHORT_DESCRIPTION = 1;
private Context context;
private List<BaseMessage> messages;
private AppDatabase appDatabase;
private Typeface typeface;
public MessagesAdapter(Context context, List<BaseMessage> messages) {
this.context = context;
this.messages = messages;
appDatabase = Room.databaseBuilder(context, AppDatabase.class, "app_database").allowMainThreadQueries().build();
typeface = Typeface.createFromAsset(context.getAssets(), "MainFont.ttf");
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
if (viewType == VIEW_TYPE_SHORT_DESCRIPTION) {
return new DescriptionViewHolder(inflater.inflate(R.layout.row_short_description, parent, false));
} else {
return new MessageViewHolder(inflater.inflate(R.layout.row_message, parent, false));
}
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
int viewType = getItemViewType(position);
if (viewType == VIEW_TYPE_SHORT_DESCRIPTION) {
DescriptionViewHolder viewHolder1 = (DescriptionViewHolder) holder;
viewHolder1.txtShortDescription.setTypeface(typeface);
viewHolder1.txtShortDescription.setText(MessagesActivity.description);
} else {
MessageViewHolder viewHolder = (MessageViewHolder) holder;
Message message = (Message) messages.get(position);
viewHolder.txtMessage.setTypeface(typeface);
if (position % 2 == 0) {
viewHolder.linearLayout1.setBackgroundColor(context.getResources().getColor(R.color.m_a_1_row_background_1));
viewHolder.txtMessage.setTextColor(context.getResources().getColor(R.color.m_a_1_row_category_name_2));
} else {
viewHolder.linearLayout1.setBackgroundColor(context.getResources().getColor(R.color.m_a_1_row_background_2));
viewHolder.txtMessage.setTextColor(context.getResources().getColor(R.color.m_a_1_row_category_name_1));
}
if (appDatabase.favoriteDao().getMessage(message.getId()).size() == 0) {
viewHolder.imgFavorite.setColorFilter(context.getResources().getColor(R.color.white), PorterDuff.Mode.SRC_IN);
} else {
viewHolder.imgFavorite.setColorFilter(context.getResources().getColor(R.color.cinnabar), PorterDuff.Mode.SRC_IN);
}
viewHolder.txtMessage.setText(message.getMessage());
}
}
@Override
public int getItemCount() {
return messages.size();
}
@Override
public int getItemViewType(int position) {
BaseMessage base = messages.get(position);
if (base instanceof MessageDescription) {
return VIEW_TYPE_SHORT_DESCRIPTION;
} else {
return VIEW_TYPE_MESSAGE;
}
}
class MessageViewHolder extends RecyclerView.ViewHolder {
@BindView(R.id.linear_layout_1)
LinearLayout linearLayout1;
@BindView(R.id.txt_message)
TextView txtMessage;
@BindView(R.id.img_favorite)
ImageView imgFavorite;
@BindView(R.id.img_copy)
ImageView imgCopy;
@BindView(R.id.img_share)
ImageView imgShare;
MessageViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
@OnClick({R.id.img_share, R.id.img_copy, R.id.img_favorite})
void onClick(View view) {
Message message = (Message) messages.get(getAdapterPosition());
switch (view.getId()) {
case R.id.img_share:
Intent intent = new Intent(Intent.ACTION_SEND);
intent.putExtra(Intent.EXTRA_TEXT, message.getMessage());
intent.setType("text/plain");
context.startActivity(Intent.createChooser(intent, ""));
break;
case R.id.img_copy:
ClipboardManager clipboard = (ClipboardManager) context.getSystemService(CLIPBOARD_SERVICE);
clipboard.setPrimaryClip(ClipData.newPlainText("copied", message.getMessage()));
CustomToast.show(context, context.getResources().getString(R.string.copied));
break;
case R.id.img_favorite:
if (appDatabase.favoriteDao().getMessage(message.getId()).size() == 0) {
FavoriteEntity favoriteEntity = new FavoriteEntity();
favoriteEntity.setId(message.getId());
favoriteEntity.setMessage(message.getMessage());
favoriteEntity.setCategoryName(message.getCategoryName());
appDatabase.favoriteDao().addMessage(favoriteEntity);
CustomToast.show(context, context.getResources().getString(R.string.added_to_favorite));
imgFavorite.setColorFilter(context.getResources().getColor(R.color.cinnabar), PorterDuff.Mode.SRC_IN);
} else {
appDatabase.favoriteDao().deleteMessage(message.getId());
CustomToast.show(context, context.getResources().getString(R.string.removed_from_favorite));
imgFavorite.setColorFilter(context.getResources().getColor(R.color.white), PorterDuff.Mode.SRC_IN);
}
break;
}
}
}
class DescriptionViewHolder extends RecyclerView.ViewHolder {
@BindView(R.id.linear_layout_1)
LinearLayout linearLayout1;
@BindView(R.id.txt_short_description)
TextView txtShortDescription;
DescriptionViewHolder(View itemView) {
super(itemView);
ButterKnife.bind(this, itemView);
}
}
}
然后从你的 Activity 中:
// Create a description object
MessageDescription description = MessageDescription();
List<Message> messages = ... // get your messages from the DB, convert them to Message class
// Combine the description and messages into one list
List<BaseMessage> combinedMessages = new ArrayList<>();
// Put description on the first place
combinedMessages.add(description);
combinedMessages.addAll(messages);
MessagesAdapter adapter = new MessagesAdapter(this, combinedMessages);
recyclerView.adapter = adapter;
关于android - 如何在不替换项目的情况下在一个 Recyclerview 中添加两个自定义行？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/58640553/