Expandable list view is used to group list data by categories. It has the capability of expanding and collapsing the groups when user touches header. If you are not aware of list view before please refer to this tutorial Android ListView Tutorial. I left my main activity name as MainActivity. In order to create an expandable list view, we need three xml layout files. First one is for main listview, 2nd one for list view group item and 3rd one is for list view child item.

Create another xml layout for list view group header. This will contain simple TextView element. I am using a custom adapter class to create list view. Create a new class file called ExpandableListAdapter. This class provides required methods to render listview. Once you are done with customer adapter, open your MainActivity.

expandable recyclerview android

In the following I created required data needed for list view and passed it to custom adapter. Run your project, you should see following output. Note: The list view group indicators might change depending upon your android version. Detecting the child item click can be done by implementing setOnChildClickListener listener on listview. You may want to execute some lines of code when the listview group is expanded.

For this you can use setOnGroupExpandListener which triggers an event when listview group expanded. Implementing setOnGroupCollapseListener will trigger an event when listview group is collapsed. Ravi… excellent work… Anyone can make great apps relying on codes presented here. Through people like you we will be increasing the overall quality of android apps.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. The idea is that there is a parent list, when an list item in the parent list is tapped, that list item reveals a child list that contains it's own data.

I've tried to get it working for the past 3 days to no avail. I tried using the AdvancedReyclerview library but to a beginner like me, it was a giant mess of things that didn't make sense especially when passing in the data.

I copied and pasted files that I needed to get a minimal working version but I had no idea how to pass my data into the recyclerview and how to update it with the newly selected value.

Any thoughts on that? You can check my library in here. You can easily achieve it with this librarythere is a full example here. Learn more. Creating an expandable RecyclerView Ask Question. Asked 4 years, 11 months ago. Active 1 month ago. Viewed 36k times. I'm trying to implement a recyclerview that behaves like my sketch below: The idea is that there is a parent list, when an list item in the parent list is tapped, that list item reveals a child list that contains it's own data.

Is it even possible to do what I'm trying to do or am I way out of my depth here? If it's still difficult to understand, I can explain it more. Darush 7, 4 4 gold badges 43 43 silver badges 47 47 bronze badges.Android ExpandableListView is a view that shows items in a vertically scrolling two-level list. It differs from a ListView by allowing two levels which are groups that can be easily expanded and collapsed by touching to view and their respective children items.

ExpandableListViewAdapter in android loads the data into the items associated with this view. In the above code the expandableListDetail object is used to map the group header strings to their respective children using an ArrayList of Strings. This class extends BaseExpandableListAdapter and it overrides the methods in the base class to provide the view for the ExpandableListView.

But these can be easily modified to perform any other operations. This brings an end to Android ExpandableListView tutorial. Thanks for this tutorial.

Hi, is it possible to shift the position of items? Like according to your example I want to change the team position as first to display basketball then wants to display cricket after I want to display football Team. Hihow can i populate Expendable listView using Json from Volley and mysql I have 2 tables Article and commentsotherly how can i use dynamic data.

The response you get is key-value pair and HashMap stores the key-value data. Hello Team, Thank you for the detailed information. A very nice example for a beginner. If the ExpandabeListView expands off the bottom screen, it does not scroll! Is there a solution to this? SIr…Great work. I have got without any errors.

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I have a doubt,…. Hi, This tutorial useful. But i need this expandablelistview as expand and collapse. That is if child layout expanded ,then all the parent layouts should collapse. And need to add data from API. Please, could you let me know how I can add a search feature to this and when I select a child object I would like to open another activity using string. Returns error: java.A flexible view for providing a limited window into a large data set.

Glossary of terms: Adapter: A subclass of RecyclerView. Adapter responsible for providing views that represent items in a data set. Position: The position of a data item within an Adapter. Index: The index of an attached child view as used in a call to getChildAt int. Contrast with Position. Binding: The process of preparing a child view to display data corresponding to a position within the adapter.

Recycle view : A view previously used to display data for a specific adapter position may be placed in a cache for later reuse to display the same type of data again later. This can drastically improve performance by skipping initial layout inflation or construction. Scrap view : A child view that has entered into a temporarily detached state during layout.

Scrap views may be reused without becoming fully detached from the parent RecyclerView, either unmodified if no rebinding is required or modified by the adapter if the view was considered dirty. Dirty view : A child view that must be rebound by the adapter before being displayed. Adapter and RecyclerView. LayoutManager to be able to detect data set changes in batches during a layout calculation. This saves LayoutManager from tracking adapter changes to calculate animations.

It also helps with performance because all view bindings happen at the same time and unnecessary bindings are avoided. For this reason, there are two types of position related methods in RecyclerView: layout position: Position of an item in the latest layout calculation. This is the position from the LayoutManager's perspective.

expandable recyclerview android

This is the position from the Adapter's perspective. These two positions are the same except the time between dispatching adapter. These positions include all changes until the last layout calculation. You can rely on these positions to be consistent with what user is currently seeing on the screen. For example, if you have a list of items on the screen and user asks for the 5 th element, you should use these methods as they'll match what user is seeing.

For example, if you want to access the item in the adapter on a ViewHolder click, you should use getAdapterPosition. Beware that these methods may not be able to calculate adapter positions if notifyDataSetChanged has been called and new layout has not yet been calculated.

When writing a RecyclerView. LayoutManager you almost always want to use layout positions whereas when writing an RecyclerView. Adapteryou probably want to use adapter positions. Base class for an Adapter Adapters provide a binding from an app-specific data set to views that are displayed within a RecyclerView.

Observer base class for watching changes to an RecyclerView. This class defines the animations that take place on items as changes are made to the adapter. An ItemDecoration allows the application to add a special drawing and layout offset to specific item views from the adapter's data set.If your app needs to display a scrolling list of elements based on large data sets or data that frequently changesyou should use RecyclerView as described on this page.

Then simply add the fragment to your activity layout. Figure 1. A list using RecyclerView. Figure 2. A list also using CardView. If you'd like to create a list with cards, as shown in figure 2, also use the CardView widget as described in Create a Card-based Layout. The RecyclerView widget is a more advanced and flexible version of ListView. In the RecyclerView model, several different components work together to display your data. The overall container for your user interface is a RecyclerView object that you add to your layout.

The RecyclerView fills itself with views provided by a layout manager that you provide. You can use one of our standard layout managers such as LinearLayoutManager or GridLayoutManageror implement your own. The views in the list are represented by view holder objects.

These objects are instances of a class you define by extending RecyclerView. Each view holder is in charge of displaying a single item with a view. For example, if your list shows music collection, each view holder might represent a single album.

The RecyclerView creates only as many view holders as are needed to display the on-screen portion of the dynamic content, plus a few extra. As the user scrolls through the list, the RecyclerView takes the off-screen views and rebinds them to the data which is scrolling onto the screen.

The view holder objects are managed by an adapterwhich you create by extending RecyclerView. The adapter creates view holders as needed. The adapter also binds the view holders to their data. It does this by assigning the view holder to a position, and calling the adapter's onBindViewHolder method. That method uses the view holder's position to determine what the contents should be, based on its list position. This RecyclerView model does a lot of optimization work so you don't have to:.

To access the RecyclerView widget, you need to add the v7 Support Libraries to your project as follows:.Expandable Recycler view is alternative of ExpandableListView. It fails in the coordinator layout as well as have layout height issue.

Introducing ExpandableRecyclerView

SubcategoryParentListItem is our parent class that is used to store the data relevant to parent. SubcategoryChildListItem is our simple child class used to display the content in each child of parent.

IllegalStateException: Null object added at com. We use cookies to personalize your experience. By continuing to visit this website you agree to our use of cookies. Learn more about privacy policy. Shubham Agarwal 29 April Custom Parent and Child Classed used to represent the relationship SubcategoryParentListItem is our parent class that is used to store the data relevant to parent.

Comments 10 Cancel reply Add Your Comment. Thanks in advance. This is because we are binding the views using this adapter. Shubham Agarwal December 26, at pm Child are automatically expanded if child item list is neither null and nor empty. Hire Us! We have just recieved your project brief and our expert will contact you shortly. Send Again.Epoxyan Android library developed by Airbnb, is a widely known and used library for building complex screens in a RecyclerView.

It has built-in support for async diffing using DiffUtil and promotes immutability while enforcing best practices when working with RecyclerView. Epoxy provides various ways to generate the Epoxy models. To get this to work, you have to include the following dependencies in build. We have 2 data binding variables:.

OnClickListener instead of a custom interface or Kotlin lambda so that Epoxy will ignore it when it does the diffing.

Android - Expandable RecyclerView

This model will represent a single game title. Create a Kotlin file with the following data classes:. We have a global ID generator here to make sure that each object gets a unique ID.

This is where the magic happens. Taking a closer look at Genre class, we see that we have a property isExpanded which is false by default. When the genre header is clicked, the onClick listener that we wired up in XML will be invoked — passing along the Epoxy model that was associated to it.

We get the Genre instance from the model and pass it to the listener that we defined in the container. Note that having unique identifiers per each model is key to proper diffing.

expandable recyclerview android

Epoxy compares the old and new models by their IDs and content. The interesting part is the implementation of OnGenreExpanded. It might seem inefficient to make copies of the objects instead of just modifying them directly, but immutability is key for bug free code.

Finally, we connect all the pieces together. Create a new Activity called GamesListActivity with the following code:. We observe gamesLiveData from the GamesListViewModel and every time a new container is emitted, we simply forward it to the Epoxy controller.

You can now run the app and see it in action! If you liked this article, please remember to clap and follow me here on Medium and on Twitter for more articles in the future.

Special thanks to Mikko-Ville Salo for guiding me on this topic. Sign in. Submit Archive About Events droidcon. Expandable RecyclerView with Epoxy. Nimrod Dayan Follow.

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Software Engineer specialized in Android. Helsinki, Finland. Thanks to Antonio Gutierrez. ProAndroidDev Follow. See responses 2. More From Medium. More from ProAndroidDev. Somesh Kumar in ProAndroidDev. Denys Soroka in ProAndroidDev.

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