An Android fancy accordion view,
To run the example demo, clone the repo, import the project in Android Studio and run the app.
FancyAccordionView is a custom view that can be used for showing a list of items. It extends RecyclerView and offers the following features:
- allows you to expand and collapse each item
 - allows custom layout for extended/collapsed item
 - callback for extended/collapsed item click
 - scroll up the clicked item
 - multiple layout for extended/collapsed item
 
To use the FancyAccordionView in your project follow this steps.
- in Project level 
build.gradleadd this repository 
   maven { url  'https://dl.bintray.com/sysdata/maven' }- in your App level 
build.gradleadd this dependency 
    implementation 'it.sysdata.mobile:fancyaccordionview:1.0.1'Open your layout file and add the FancyAccordionView:
<com.sysdata.widget.accordion.FancyAccordionView
        android:id="@+id/fancy_accordion_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipToPadding="false"
        android:descendantFocusability="beforeDescendants"
        android:fadingEdgeLength="0dp"
        android:scrollbarStyle="outsideOverlay"
        android:scrollbars="vertical"
        android:splitMotionEvents="false"
        tools:listitem="@layout/sample_layout_collapsed"/>
Create your custom layout for collapsed and expanded item.
Example for collapsed item sample_layout_collapsed:
<RelativeLayout
    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="wrap_content"
    android:background="?attr/selectableItemBackground"
    android:paddingEnd="16dp"
    android:paddingStart="16dp">
    
    <TextView
        android:id="@+id/sample_layout_collapsed_title"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:layout_alignParentStart="true"
        android:gravity="center_vertical"
        android:textColor="@android:color/black"
        tools:text="Collapsed View"/>
        
    <com.sysdata.widget.accordion.ArrowImageView
        android:layout_width="wrap_content"
        android:layout_height="48dp"
        android:layout_alignParentRight="true"
        android:tint="@android:color/black"
        app:expanded="false"/>
        
</RelativeLayout>
Example for expanded item sample_layout_expanded:
<RelativeLayout
    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="wrap_content"
    android:background="?attr/selectableItemBackground"
    android:paddingEnd="16dp"
    android:paddingStart="16dp">
    <TextView
        android:id="@+id/sample_layout_expanded_title"
        android:layout_width="match_parent"
        android:layout_height="48dp"
        android:layout_alignParentStart="true"
        android:gravity="center_vertical"
        android:textColor="@android:color/black"
        tools:text="Expanded View"/>
    <TextView
        android:id="@+id/sample_layout_expanded_description"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/sample_layout_expanded_title"
        android:gravity="top"
        android:minHeight="48dp"
        android:paddingBottom="8dp"
        tools:text="I'm an Expanded View"/>
    <com.sysdata.widget.accordion.ArrowImageView
        android:layout_width="wrap_content"
        android:layout_height="48dp"
        android:layout_alignParentRight="true"
        android:tint="@android:color/black"
        app:expanded="true"/>
</RelativeLayout>
Create your custom listener for item click, for example:
private ItemAdapter.OnItemClickedListener mListener = new ItemAdapter.OnItemClickedListener() {
    @Override
    public void onItemClicked(ItemAdapter.ItemViewHolder<?> viewHolder, int id) {
        ItemAdapter.ItemHolder itemHolder = viewHolder.getItemHolder();
        SampleItem item = ((SampleItem) itemHolder.item);
        switch (id) {
            case ItemAdapter.OnItemClickedListener.ACTION_ID_COLLAPSED_VIEW:
                showToast(String.format("Collapsed %s clicked!", item.getTitle()));
                break;
            case ItemAdapter.OnItemClickedListener.ACTION_ID_EXPANDED_VIEW:
                showToast(String.format("Expanded %s clicked!", item.getTitle()));
                break;
            default:
                // do nothing
                break;
        }
    }
};
Get the reference to FancyAccordionView, set the layout for collapsed/expanded item, set the listener for item click and load your data into list.
FancyAccordionView mRecyclerView = (FancyAccordionView) findViewById(R.id.alarms_recycler_view);
// bind the factory to create view holder for item collapsed
mRecyclerView.setCollapsedViewHolderFactory(SampleCollapsedViewHolder.Factory.create(R.layout.sample_layout_collapsed), mListener);
// bind the factory to create view holder for item expanded
mRecyclerView.setExpandedViewHolderFactory(SampleExpandedViewHolder.Factory.create(R.layout.sample_layout_expanded), mListener);
// restore the expanded item from state
if (savedInstanceState != null) {
    mRecyclerView.setExpandedItemId(savedInstanceState.getLong(KEY_EXPANDED_ID, Item.INVALID_ID));
}
// populate RecyclerView with mock data
loadData();
It is also possible to define different view types.
    // bind the factory to create view holder for item collapsed of type 1
    mRecyclerView.setCollapsedViewHolderFactory(
            SampleCollapsedViewHolder.Factory.create(R.layout.sample_layout_collapsed),
            mListener,
            VIEW_TYPE_1
    );
    // bind the factory to create view holder for item collapsed of type 2
    mRecyclerView.setCollapsedViewHolderFactory(
            SampleCollapsedViewHolder.Factory.create(R.layout.sample_layout_collapsed_type2),
            mListener,
            VIEW_TYPE_2
    );
    // bind the factory to create view holder for item expanded of type 1
    mRecyclerView.setExpandedViewHolderFactory(
            SampleExpandedViewHolder.Factory.create(R.layout.sample_layout_expanded),
            mListener,
            VIEW_TYPE_1
    );
    // bind the factory to create view holder for item expanded of type 2
    mRecyclerView.setExpandedViewHolderFactory(
            SampleExpandedViewHolder.Factory.create(R.layout.sample_layout_expanded_type2),
            mListener,
            VIEW_TYPE_2
    );
  Copyright (C) 2017 Sysdata S.p.A.
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
      http://www.apache.org/licenses/LICENSE-2.0
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
