Android Studio使用recyclerview实现展开和折叠功能（在之前的微信页面基础之上）

<?xml version=\"1.0\" encoding=\"utf-8\"?>
<LinearLayout xmlns:android=\"http://schemas.android.com/apk/res/android\"
 xmlns:app=\"http://schemas.android.com/apk/res-auto\"
 android:layout_width=\"match_parent\"
 android:layout_height=\"wrap_content\"
 xmlns:tools=\"http://schemas.android.com/tools\"
 android:orientation=\"vertical\">
<RelativeLayout
  android:id=\"@+id/rl_parent\"
  android:layout_width=\"match_parent\"
  android:layout_height=\"50dp\"
  android:background=\"#00574B\">

  <TextView
   android:id=\"@+id/textViewparent\"
   android:layout_width=\"wrap_content\"
   android:layout_height=\"wrap_content\"
   android:textSize=\"30dp\"
   android:layout_centerInParent=\"true\"
   android:textColor=\"@android:color/white\"
   tools:text=\"主布局\" />
 </RelativeLayout>

 <RelativeLayout
  android:id=\"@+id/rl_child\"
  android:layout_width=\"match_parent\"
  android:layout_height=\"100dp\"
  android:background=\"#ffffff\"
  android:visibility=\"gone\">

  <ImageView
   android:id=\"@+id/imageview\"
   android:layout_width=\"wrap_content\"
   android:layout_height=\"wrap_content\" />

  <TextView
   android:id=\"@+id/textViewchild\"
   android:layout_width=\"wrap_content\"
   android:layout_height=\"wrap_content\"
   android:layout_centerInParent=\"true\"
   android:textSize=\"25dp\"
   android:textColor=\"#000000\"
   tools:text=\"副部局\" />
 </RelativeLayout>
</LinearLayout>

<?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:orientation=\"vertical\">
 <include layout=\"@layout/top\" />
 <FrameLayout
  android:id=\"@+id/id_content\"
  android:layout_width=\"match_parent\"
  android:layout_height=\"0dp\"
  android:layout_weight=\"1\">
  <android.support.v7.widget.RecyclerView
   android:id=\"@+id/recyclerView\"
   android:layout_width=\"match_parent\"
   android:layout_height=\"match_parent\">
  </android.support.v7.widget.RecyclerView>
 </FrameLayout>
 <include layout=\"@layout/bottom\" />
</LinearLayout>

public class adapter extends RecyclerView.Adapter <adapter.myviewholder>{
 private List<String> mlist=new ArrayList<>();
 private Context context;
 private View inflater;
 private static final String tag=adapter.class.getSimpleName();
 private int expandedPosition=1;
 private myviewholder mViewHolder;
 public adapter(Context context) {//,List<String> list
  this.context=context;
 }
 public void setExpandCollapseDataList(List<String> list){
  mlist=list;
  notifyDataSetChanged();
 }
 @Override
 public adapter.myviewholder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
  inflater= LayoutInflater.from(context).inflate(R.layout.tab01,viewGroup,false);
  myviewholder myviewholder=new myviewholder(inflater);
  return myviewholder;
 }
 @Override
 public void onBindViewHolder(final adapter.myviewholder myviewholder, final int j) {
  myviewholder.textviewparent.setText(mlist.get(j));
  myviewholder.imageview.setImageResource(R.drawable.p1);
  myviewholder.textviewchild.setText(mlist.get(j+15));
  final boolean isExpanded=j==expandedPosition;
  myviewholder.rlChild.setVisibility(isExpanded ? View.VISIBLE : View.GONE);
  myviewholder.rlParent.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    if (mViewHolder != null) {
     mViewHolder.rlChild.setVisibility(View.GONE);
     notifyItemChanged(expandedPosition);
    }
    expandedPosition = isExpanded ? -1 : myviewholder.getAdapterPosition();
    mViewHolder = isExpanded ? null : myviewholder;
    notifyItemChanged(myviewholder.getAdapterPosition());
   }
  });
 }
 @Override
 public int getItemCount() {
  return mlist == null ? 0 : mlist.size()/2;
 }
 class myviewholder extends RecyclerView.ViewHolder{
  private ImageView imageview;
  RelativeLayout rlParent, rlChild;
  TextView textviewparent, textviewchild;
  public myviewholder(View itemView) {
   super(itemView);
   rlParent = itemView.findViewById(R.id.rl_parent);
   rlChild = itemView.findViewById(R.id.rl_child);
   textviewparent = itemView.findViewById(R.id.textViewparent);
   textviewchild = itemView.findViewById(R.id.textViewchild);
   imageview=itemView.findViewById(R.id.imageview);
  }
 }
}

private void initmyData() {
 list.add(\"路德维希·凡·贝多芬\");
 list.add(\"萧友梅\");
 list.add(\"阿炳\");
 list.add(\"冼星海\");
 list.add(\"聂耳\");
 list.add(\"施光南\");
 list.add(\"弗里德里克·肖邦\");
 list.add(\"罗伯特·舒曼\");
 list.add(\"莫扎特\");
 list.add(\"约瑟夫·海顿\");
 list.add(\"舒伯特\");
 list.add(\"巴赫\");
 list.add(\"弗仑兹·李斯特\");
 list.add(\"约翰奈斯·勃拉姆斯\");
 list.add(\"门德尔松\");
 list.add(\"德国作曲家、钢琴家、指挥家，被称为乐圣。\");
 list.add(\"中国专业音乐教育的奠基人和开拓者、音乐理论家、作曲家。\");
 list.add(\"民间音乐家、二胡演奏家，誉为演奏能手。\");
 list.add(\"中国近代作曲家、钢琴家--人民音乐家。\");
 list.add(\"中国音乐家--时代歌手。\");
 list.add(\"誉为时代歌手，现代抒情歌曲作曲家。\");
 list.add(\"誉为钢琴诗人，波兰作曲家、钢琴家。\");
 list.add(\"德国著名作曲家、音乐评论家。\");
 list.add(\"奥地利作曲家，被誉为神童。\");
 list.add(\"奥地利作曲家，维也纳古典派奠基者之一。\");
 list.add(\"奥地利作曲家--前所未有的最富诗意的音乐家。\");
 list.add(\"德国最伟大的古典作曲家之一，管风琴演奏家。\");
 list.add(\"天才的匈牙利作曲家、钢琴家、指挥家和音乐活动家。\");
 list.add(\"德国十九世纪后半叶最卓越的、古典乐派最后的一位作曲家。\");
 list.add(\"德国著名作曲家。\");
}

private void initView1() {
 adapter adapter = new adapter(this);
 RecyclerView recyclerView = findViewById(R.id.recyclerView);
 recyclerView.setLayoutManager(new LinearLayoutManager(this));
 recyclerView.setHasFixedSize(true);
 recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));
 recyclerView.setAdapter(adapter);
 adapter.setExpandCollapseDataList(list);
}