RecyclerView ViewType二级

实现效果描述：
1、点击recyclerview中item，列表下方出现其他样式的item，作为子item，如下所示

所需要的java文件和xml文件有：

1、创建FoldAdapteradapter, 在FoldAdapter中，定义两种不同的类型，分别对应父item和子item，对于不同布局的item，需要设置两种不同的viewHoder进行设置。
2、在onCreateViewHolder进行对于布局的绑定
3、在onBindViewHoder中进行数据的操作
4、在getItemViewType返回对应的类型
5、在getItemCount中返回对应的大小

FoldAdapter：

package com.example.expandtworecyclerviewdemo;import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;import org.w3c.dom.Text;import java.util.ArrayList;
import java.util.List;
import java.util.PropertyResourceBundle;
import java.util.zip.Inflater;public class FoldAdapteer extends RecyclerView.Adapter<RecyclerView.ViewHolder> {private static final int PARENT_TYPE = 0X0000;private static final int CHILD_TYPE = 0X0001;private Context mContext;private List<ITyple> dataList = new ArrayList<>();public FoldAdapteer(Context context){mContext = context;}public void setData(List<ITyple> iTyples){//对于list的数据不能简单的是等于的操作this.dataList.clear();this.dataList.addAll(iTyples);notifyDataSetChanged();}@Overridepublic int getItemViewType(int position) {if (dataList.get(position).getTyple() == EType.PARENT_TYPE) {return PARENT_TYPE;}if (dataList.get(position).getTyple() == EType.CHILD_TYPE){return CHILD_TYPE;}return super.getItemViewType(position);}@NonNull@Overridepublic RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {if (viewType == PARENT_TYPE){View mView = LayoutInflater.from(mContext).inflate(R.layout.parent_layout, parent, false);return new ParentHoder(mView);}else if (viewType == CHILD_TYPE){View mView = LayoutInflater.from(mContext).inflate(R.layout.child_layout, parent, false);return new ChildHoder(mView);}return null;}@Overridepublic void onBindViewHolder(@NonNull final RecyclerView.ViewHolder holder, final int position) {if (holder instanceof ParentHoder){ParentHoder parentHoder = (ParentHoder)holder;final DateBean.ParentBean parentBean = (DateBean.ParentBean) dataList.get(position);parentHoder.itemView.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {Log.d("lucky", "onClick: " + parentBean);if (parentBean.isExpand()){closeParent(position, parentBean);((ParentHoder) holder).mImage.setImageResource(R.drawable.icon_parent_down);}else {openParent(position, parentBean);((ParentHoder) holder).mImage.setImageResource(R.drawable.icon_parent_right);}parentBean.setExpand(!parentBean.isExpand());}});DateBean.ParentBean bindata = (DateBean.ParentBean) dataList.get(position);((ParentHoder) holder).mImage.setImageResource(R.drawable.icon_parent_down);((ParentHoder) holder).text.setText(bindata.getTextParent());}else if (holder instanceof ChildHoder){DateBean.ChildBean childBean = (DateBean.ChildBean)dataList.get(position);((ChildHoder) holder).text.setText(childBean.getTextChild());}}private void openParent(int position , DateBean.ParentBean parentBean) {Log.d("lucky", "openParent: "  + dataList.get(position));//  DateBean.ParentBean parentBean = (DateBean.ParentBean)dataList.get(position);List<DateBean.ChildBean> child = parentBean.getChildBeans();dataList.addAll(position+1, child);//      notifyDataSetChanged();notifyItemRangeInserted(position+1, child.size());notifyItemRangeChanged(position+1, child.size());
//     //   notifyItemChanged(position);}private void closeParent(int position, DateBean.ParentBean parentBean) {// = (DateBean.ParentBean)dataList.get(position);List<DateBean.ChildBean> child = parentBean.getChildBeans();dataList.removeAll(child);notifyItemRangeRemoved(0,child.size());notifyDataSetChanged();//   notifyItemRangeInserted(position+1, child.size());//     notifyItemRangeChanged(position+1, child.size());}@Overridepublic int getItemCount() {return dataList.size();}private static class ParentHoder extends RecyclerView.ViewHolder {private TextView text;private ImageView mImage;public ParentHoder(@NonNull View itemView) {super(itemView);text = itemView.findViewById(R.id.parent_id);mImage = itemView.findViewById(R.id.paren_image);}}private static class ChildHoder extends RecyclerView.ViewHolder{private TextView text;public ChildHoder(@NonNull View itemView) {super(itemView);text = itemView.findViewById(R.id.child_id);}}
}

DataBean

package com.example.expandtworecyclerviewdemo;import android.widget.TextView;import java.util.List;public class DateBean {private List<ParentBean> parentBean;public List<ParentBean> getParentBean() {return parentBean;}public void setParentBean(List<ParentBean> parentBean) {this.parentBean = parentBean;}public static class ParentBean implements ITyple {private List<ChildBean> childBeans;private boolean isExpand = false;private String textParent;public String getTextParent() {return textParent;}public void setTextParent(String textParent) {this.textParent = textParent;}public boolean isExpand() {return isExpand;}public void setExpand(boolean expand) {isExpand = expand;}public List<ChildBean> getChildBeans() {return childBeans;}public void setChildBeans(List<ChildBean> childBeans) {this.childBeans = childBeans;}@Overridepublic EType getTyple() {return EType.PARENT_TYPE;}}public static class ChildBean implements ITyple{private String textChild;public String getTextChild() {return textChild;}public void setTextChild(String textChild) {this.textChild = textChild;}@Overridepublic EType getTyple() {return EType.CHILD_TYPE;}}
}

接口的作用，是为了使得ParentBean和ChildBean实现接口，从而返回对应的类型，执行相关的操作。
在写代码过程中，有个点可能会比较疑问，为什么在adapter中有泛型为IType的集合？
因为这样的话，根据不同的类型执行后获取的数据，可通过强制装换获取存在的数据为身为子类的ParenBean和ChildBean。

接口IType

package com.example.expandtworecyclerviewdemo;public interface ITyple {EType getTyple();
}

列举不同的数据，枚举是默认从0开始计数。

枚举EType

package com.example.expandtworecyclerviewdemo;public enum EType {PARENT_TYPE,CHILD_TYPE
}

MainActivity

package com.example.expandtworecyclerviewdemo;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.widget.Adapter;import java.util.ArrayList;
import java.util.List;public class MainActivity extends AppCompatActivity {List<ITyple> iTyples = new ArrayList<>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);//绑定对应的layout文件this.setContentView(R.layout.activity_main);RecyclerView mRecyclerView = this.findViewById(R.id.recyclerview);//加载recycler中的布局，缺少会报错RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this);FoldAdapteer recyclerAdapter = new FoldAdapteer(this);mRecyclerView.setLayoutManager(layoutManager);mRecyclerView.setAdapter(recyclerAdapter);//数据的输入for (int i= 0; i< 10 ; i++){DateBean.ParentBean parentBean = new DateBean.ParentBean();List<DateBean.ChildBean> childBean = new ArrayList<>();parentBean.setTextParent(i + " -> parren ");for (int j =0 ; j< 10 ; j++){DateBean.ChildBean childBean1 = new DateBean.ChildBean();childBean1.setTextChild(j + "-> child");childBean.add(childBean1);}parentBean.setChildBeans(childBean);iTyples.add(parentBean);}//数据传送到FolderAdapter中recyclerAdapter.setData(iTyples);}
}

main_xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".MainActivity"><androidx.recyclerview.widget.RecyclerViewandroid:id="@+id/recyclerview"android:layout_width="match_parent"android:layout_height="wrap_content"app:layout_constraintBottom_toBottomOf="parent"app:layout_constraintLeft_toLeftOf="parent"app:layout_constraintRight_toRightOf="parent"app:layout_constraintTop_toTopOf="parent" /></androidx.constraintlayout.widget.ConstraintLayout>

parent_layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="horizontal"android:background="#5FC0EC"xmlns:android="http://schemas.android.com/apk/res/android"><ImageViewandroid:id="@+id/paren_image"android:layout_width="30dp"android:layout_height="12dp"android:layout_gravity="center"/><TextViewandroid:id="@+id/parent_id"android:layout_width="match_parent"android:layout_height="30dp"/>
</LinearLayout>

child_layout

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/child_id"android:layout_width="match_parent"android:layout_height="40dp"android:background="#BA9CF0">
</TextView>

三级标题确实是一样的处理方式，就是在childData中再加一个list放数据，然后在adapter进行点击处理的效果。