code perfect

app/src/main/AndroidManifest.xml

@@ -9,6 +9,8 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
+        <activity android:name=".PinnedHeaderActivity">
+        </activity>
         <activity android:name=".MainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>

app/src/main/java/com/mxdl/customview/MainActivity.java

@@ -19,6 +19,7 @@ public class MainActivity extends AppCompatActivity implements View.OnClickListe
 
     private Button mBtnStickyLayout;
     private Button mBtnScrollView;
+    private Button mBtnPinnedHeader;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -26,11 +27,11 @@ public class MainActivity extends AppCompatActivity implements View.OnClickListe
         setContentView(R.layout.activity_main);
         mBtnStickyLayout = findViewById(R.id.btn_sticky_layout);
         mBtnScrollView = findViewById(R.id.btn_scroll_view);
+        mBtnPinnedHeader = findViewById(R.id.btn_pinned_header);
+
         mBtnStickyLayout.setOnClickListener(this);
         mBtnScrollView.setOnClickListener(this);
-
-        HorizontalScrollView scrollView;
-        NestedScrollView h;
+        mBtnPinnedHeader.setOnClickListener(this);
 
     }
 
@@ -43,6 +44,9 @@ public class MainActivity extends AppCompatActivity implements View.OnClickListe
             case R.id.btn_scroll_view:
                 startActivity(new Intent(this, HorizontalScrollViewActivity.class));
                 break;
+            case R.id.btn_pinned_header:
+                startActivity(new Intent(this,PinnedHeaderActivity.class));
+                break;
         }
     }
 }

app/src/main/java/com/mxdl/customview/PinnedHeaderActivity.java

+package com.mxdl.customview;
+
+import android.support.v7.app.AppCompatActivity;
+import android.os.Bundle;
+
+import com.mxdl.customview.adapter.ExpandableListViewAdapter;
+import com.mxdl.customview.view.PinnedHeaderExpandableListView;
+/**
+ * Description: <PinnedHeaderActivity><br>
+ * Author:      mxdl<br>
+ * Date:        2019/10/10<br>
+ * Version:     V1.0.0<br>
+ * Update:     <br>
+ */
+public class PinnedHeaderActivity extends AppCompatActivity {
+    private PinnedHeaderExpandableListView mExpandableListView;
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_pinned_header);
+        mExpandableListView = findViewById(R.id.view_expand_listview);
+        mExpandableListView.setAdapter(new ExpandableListViewAdapter(this));
+        for(int i = 0; i < 3; i++){
+            mExpandableListView.expandGroup(i);
+        }
+        mExpandableListView.showPinnedHeaderView();
+
+    }
+}

app/src/main/res/layout/activity_main.xml

@@ -7,18 +7,26 @@
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:orientation="vertical">
+
         <Button
-            android:id="@+id/btn_sticky_layout"
+            android:id="@+id/btn_scroll_view"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:text="StickyLayout"
+            android:text="HorizontalScrollView"
             android:textAllCaps="false"
             />
         <Button
-            android:id="@+id/btn_scroll_view"
+            android:id="@+id/btn_pinned_header"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:text="HorizontalScrollView"
+            android:text="PinnedHeaderExpandableListView"
+            android:textAllCaps="false"
+            />
+        <Button
+            android:id="@+id/btn_sticky_layout"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:text="StickyLayout"
             android:textAllCaps="false"
             />
     </LinearLayout>

app/src/main/res/layout/activity_pinned_header.xml

+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/sticky_content"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical">
+
+    <com.mxdl.customview.view.PinnedHeaderExpandableListView
+        android:id="@+id/view_expand_listview"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"/>
+</LinearLayout>
\ No newline at end of file