使用RecyclerView展示不同布局的item
如上图所示,在使用RecyclerView过程中会出现不同布局item的情况,可以通过定义不同的ViewType来实现。
1 实现过程
此demo以书籍的分类及详细信息作为数据。
1.1 定义不同的item
首先定义父类item:ParentItem,作为Adapter的数据源
private int type; // 指定item的类型
private CategoryItem categoryItem; // 分类item
private BookItem bookItem; // 书item
书籍的分类:CategoryItem
private String categoryName;
书的详细内容:BookItem
private String bookName;
private String desc;
1.2 重写RecyclerView.Adapter中的getItemViewType()方法
首先需要重写RecyclerView.Adapter中的getItemViewType()方法,根据不同的position,返回对应布局item的ViewType供onCreateViewHolder()使用。
@Override
public int getItemViewType(int position) {
if (mList.size() == 0 || position < 0 || position >= mList.size()) {
return -1;
}
ParentItem parentItem = mList.get(position);
return parentItem.getType();
}
1.3 ViewHolder
基类ViewHolder,供业务ViewHolder实现,使用抽象方法在Adapter和ViewHolder中传递数据
public abstract class BaseHolder extends RecyclerView.ViewHolder {
public BaseHolder(@NonNull View itemView) {
super(itemView);
}
public abstract void bindView(List list, Object bean);
}
书籍的分类:CategoryViewHolder
public CategoryViewHolder(@NonNull View itemView) {
super(itemView);
}
@Override
public void bindView(List list, Object bean) {
// 分类布局的控件展示
}
书的详细内容:BookViewHolder
public BookViewHolder(@NonNull View itemView) {
super(itemView);
}
@Override
public void bindView(List list, Object bean) {
// 书籍布局的控件展示
}
1.4 Adapter部分内容
根据getItemViewType()中返回的ViewType,调用不同的ViewHolder
@NonNull
@Override
public BaseHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) { // i来自getItemViewType的return结果,默认为0,需重写getItemViewType
switch (i) {
case CATEGORY_ITEM_TYPE:
return new CategoryViewHolder(LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.layout_category_view_holder, viewGroup, false));
case BOOK_ITEM_TYPE:
return new BookViewHolder(LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.layout_book_view_holder, viewGroup, false));
default:
return new BaseHolder(new LinearLayout(viewGroup.getContext())) {
@Override
public void bindView(List list, Object bean) {
}
};
}
}
@Override
public void onBindViewHolder(@NonNull BaseHolder baseHolder, int i) {
baseHolder.bindView(mList, mList.get(i));
}
2 详细代码
2.1 分类布局layout文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/text_view_category_top"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="15dp"
android:textStyle="bold"
android:textColor="#333333"
android:layout_marginTop="35dp"
android:layout_marginBottom="10dp"
android:textSize="17sp" />
</LinearLayout>
2.2 书籍布局layout文件
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="15dp"
android:layout_marginTop="10dp"
android:background="#ffffff"
android:orientation="vertical">
<TextView
android:id="@+id/text_view_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="12dp"
android:textColor="#333333"
android:textSize="15sp"
android:textStyle="bold" />
<TextView
android:id="@+id/text_view_desc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:textColor="#666666"
android:textSize="13sp" />
</LinearLayout>
2.3 CategoryViewHolder
public class CategoryViewHolder extends BaseHolder {
private TextView textView;
public CategoryViewHolder(@NonNull View itemView) {
super(itemView);
textView = (TextView) itemView.findViewById(R.id.text_view_category_top);
}
@Override
public void bindView(List list, Object bean) {
if (bean instanceof ParentItem) {
CategoryItem item = ((ParentItem) bean).getCategoryItem();
textView.setText(item.getCategoryName());
}
}
}
2.4 BookViewHolder
public class BookViewHolder extends BaseHolder {
private TextView textViewName;
private TextView textViewDesc;
public BookViewHolder(@NonNull View itemView) {
super(itemView);
textViewName = (TextView) itemView.findViewById(R.id.text_view_name);
textViewDesc = (TextView) itemView.findViewById(R.id.text_view_desc);
}
@Override
public void bindView(List list, Object bean) {
if (bean instanceof ParentItem) {
BookItem bookItem = ((ParentItem) bean).getBookItem();
textViewName.setText(bookItem.getBookName());
textViewDesc.setText(bookItem.getDesc());
}
}
}
2.5 BookAdapter
public class BookAdapter extends RecyclerView.Adapter<BaseHolder> {
private List<ParentItem> mList = new ArrayList<>();
public static final int CATEGORY_ITEM_TYPE = 1;
public static final int BOOK_ITEM_TYPE = 2;
public BookAdapter(List<ParentItem> list) {
this.mList = list;
}
@NonNull
@Override
public BaseHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) { // i来自getItemViewType的return结果,默认为0,需重写getItemViewType
switch (i) {
case CATEGORY_ITEM_TYPE:
return new CategoryViewHolder(LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.layout_category_view_holder, viewGroup, false));
case BOOK_ITEM_TYPE:
return new BookViewHolder(LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.layout_book_view_holder, viewGroup, false));
default:
return new BaseHolder(new LinearLayout(viewGroup.getContext())) {
@Override
public void bindView(List list, Object bean) {
}
};
}
}
@Override
public void onBindViewHolder(@NonNull BaseHolder baseHolder, int i) {
baseHolder.bindView(mList, mList.get(i));
}
@Override
public int getItemCount() {
return mList.size();
}
@Override
public int getItemViewType(int position) {
if (mList.size() == 0 || position < 0 || position >= mList.size()) {
return -1;
}
ParentItem parentItem = mList.get(position);
return parentItem.getType();
}
}
2.6 MainActivity
public class MainActivity extends AppCompatActivity {
private List<ParentItem> mDatas = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
getItems();
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
recyclerView.setLayoutManager(layoutManager); // 指定布局方式为线性布局
BookAdapter adapter = new BookAdapter(mDatas);
recyclerView.setAdapter(adapter);
}
/**
* 组装item数据
*/
private void getItems() {
List<Category> categoryList = initBooks();
for (int i = 0; i < categoryList.size(); i++) {
Category category = categoryList.get(i);
ParentItem item1 = new ParentItem();
// 组装CategoryItem
CategoryItem categoryItem = new CategoryItem();
categoryItem.setCategoryName(category.getName());
item1.setType(BookAdapter.CATEGORY_ITEM_TYPE);
item1.setCategoryItem(categoryItem);
mDatas.add(item1);
// 组装BookItem
List<Book> bookList = category.getBooks();
for (int j = 0; j < bookList.size(); j++) {
ParentItem item2 = new ParentItem();
Book book = bookList.get(j);
BookItem bookItem = new BookItem();
bookItem.setBookName(book.getName());
bookItem.setDesc(book.getDesc());
item2.setType(BookAdapter.BOOK_ITEM_TYPE);
item2.setBookItem(bookItem);
mDatas.add(item2);
}
}
}
/**
* 组装书籍数据
*/
private List<Category> initBooks() {
List<Category> categoryList = new ArrayList<>();
// 第一个分类
Category category1 = new Category();
category1.setName("科幻书");
List<Book> bookList1 = new ArrayList<>();
Book book1 = new Book();
book1.setName("三体");
book1.setDesc("《三体》是刘慈欣创作的系列长篇科幻小说,由《三体》、《三体Ⅱ·黑暗森林》、《三体Ⅲ·死神永生》组成," +
"第一部于2006年5月起在《科幻世界》杂志上连载,第二部于2008年5月首次出版,第三部则于2010年11月出版。");
bookList1.add(book1);
Book book2 = new Book();
book2.setName("太空漫游四部曲");
book2.setDesc("科幻殿堂的永恒经典, 太空时代的不朽史诗全新修订精装典藏版阿瑟·克拉克,这个时代最伟大的科幻大师和太空预" +
"言家“太空漫游”系列,世界科幻文学巅峰之作。");
bookList1.add(book2);
category1.setBooks(bookList1);
categoryList.add(category1);
// 第二个分类
Category category2 = new Category();
category2.setName("小说");
List<Book> bookList2 = new ArrayList<>();
Book book3 = new Book();
book3.setName("围城");
book3.setDesc("围城》是钱钟书所著的长篇小说,是中国现代文学史上一部风格独特的讽刺小说。");
bookList2.add(book3);
Book book4 = new Book();
book4.setName("我与地坛");
book4.setDesc("《我与地坛》在 2002年5月由人民文学出版社出版发行的图书,作者为史铁生。");
bookList2.add(book4);
Book book5 = new Book();
book5.setName("雪国");
book5.setDesc("是日本作家川端康成创作的第一部中篇小说,也是他唯美主义代表之作,从1935年起以短篇的形式,分别以《暮景的镜》、《白昼的镜》等题名。");
bookList2.add(book5);
category2.setBooks(bookList2);
categoryList.add(category2);
// 第三个分类
Category category3 = new Category();
category3.setName("技术书");
List<Book> bookList3 = new ArrayList<>();
Book book6 = new Book();
book6.setName("第一行代码");
book6.setDesc("被Android开发者誉为“Android学习第一书”");
bookList3.add(book6);
category3.setBooks(bookList3);
categoryList.add(category3);
return categoryList;
}
}
3 demo下载
可在这里下载RecyclerView展示不同布局item的demo