为啥要写这个呢?前段时间面试的时候面试官问我这个问题,说一个RecyclerView如何显示两种布局,当时没回答上来(尴尬),回来时准备总结一下,然后。。就拖到了现在,趁着周末赶紧总结一下,写了一个demo,先上效果图:
说明一下,例如这里面第一行和第二行展示不同,他们并不是用一个布局文件通过控制控件展示不同的风格,而是通过两个布局文件展示的,当然这也是今天的主题,在一个RecyclerView列表里面展示两种布局。话不多说,上代码:
1.由于要展示两种布局,所以先上两种布局代码,很简单
布局文件:item_first_adapter.xml(只声明了一个textView)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
xmlns:tool="http://schemas.android.com/tools"
android:gravity="center"
android:layout_height="40dp">
<TextView
android:id="@+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="18sp"
tool:text="333"/>
</LinearLayout>
布局文件:item_second_adapter.xml(同样只声明了一个Button)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:gravity="center"
android:layout_height="40dp">
<Button
android:id="@+id/bt_button"
android:background="@color/colorPrimary"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="22sp"
android:textColor="#FFFFFF"
android:text="333"/>
</LinearLayout>
2.因为要展示数据,并且判断某条数据属于哪个布局,所以声明一个存数据的类
public class BeanItemBase {
private String name;//内容展示
private int type;//标识这条Item属于布局一或是布局二
public BeanItemBase(String name, int type) {
this.name = name;
this.type = type;
}
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
3.测试数据的准备,在一个activity或者fragment里面声明,并且把数据传到对应的Adapter中,
public class ManyItemActivity extends AppCompatActivity {
@BindView(R.id.rv_list)
RecyclerView rvList;
private ManyItemAdapter mAdapter;
private List<BeanItemBase>mItemList=new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_many_item);//这个布局很简单,就是一个线性布局,里面包着一个RecyclerView
ButterKnife.bind(this);
initView();
}
private void initView() {
mItemList.add(new BeanItemBase("张三",1));
mItemList.add(new BeanItemBase("李四",2));
mItemList.add(new BeanItemBase("王五",2));
mItemList.add(new BeanItemBase("赵六",1));
mItemList.add(new BeanItemBase("孙七",2));
mItemList.add(new BeanItemBase("周八",1));
mItemList.add(new BeanItemBase("吴九",2));
mAdapter=new ManyItemAdapter(mItemList,getBaseContext());
rvList.setLayoutManager(new LinearLayoutManager(getBaseContext()));//设置线性布局
rvList.addItemDecoration(new DividerItemDecoration(getBaseContext(),DividerItemDecoration.VERTICAL));//分隔线
rvList.setAdapter(mAdapter);
}
}
activity_many_item
<?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="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/rv_list"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
4.接下来写最重要的ManyItemAdapter写法
public class ManyItemAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<BeanItemBase> mItemList;
private Context mContext;
private final static int FIRST_VIEW_TYPE=1;//第一种布局标识
private final static int SECOND_VIEW_TYPE=2;//第二种布局标识
public ManyItemAdapter(List<BeanItemBase> mItemList, Context mContext) {
this.mItemList = mItemList;
this.mContext = mContext;
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
/*这一点需要说明,viewType是怎么来的,每次进入这个Adapter,getItemViewType会先执行,
每执行一次getItemViewType就会走一次onCrateViewHolder,然后载入对应的布局,有多少条数据,
就会执行多少次,这一块我们使用时可以打个断点看一下,非常清晰
*/
if(viewType==FIRST_VIEW_TYPE){
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_first_adapter, parent,false);
FirstHolder viewHolder = new FirstHolder(view);
return viewHolder;
}else{
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_second_adapter, parent,false);
SecondHolder secondHolder=new SecondHolder(view);
return secondHolder;
}
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
BeanItemBase beanItemBase = mItemList.get(position);
if(holder instanceof FirstHolder ) {
((FirstHolder)holder).tvName.setText(beanItemBase.getName());
}else{
((SecondHolder)holder).mButtonName.setText(beanItemBase.getName());
}
}
@Override
public int getItemViewType(int position) {
//根据 BeanItemBase类中的字段type 来判断,每条传入数据应该使用哪种布局
BeanItemBase beanItemBase=mItemList.get(position);
//字段type为1则使用布局1,为别的值使用布局2
return beanItemBase.getType()==1?FIRST_VIEW_TYPE:SECOND_VIEW_TYPE;
}
@Override
public int getItemCount() {
return mItemList.size();
}
static class FirstHolder extends RecyclerView.ViewHolder {
TextView tvName;
public FirstHolder(View view) {
super(view);
tvName = view.findViewById(R.id.tv_name);
}
}
static class SecondHolder extends RecyclerView.ViewHolder {
Button mButtonName;
public SecondHolder(View view) {
super(view);
mButtonName = view.findViewById(R.id.bt_button);
}
}
}
这个Adapter很简单,我只是在getItemViewType()使用时稍微注释了一下,别的没啥要说的了,不要光看,看会了没用,自己动手写一个小demo试试就知道了。