Expandable recyclerview android

Expandable recyclerview android

Introducing Expandable RecyclerView : an open source library for expanding and collapsing groups using RecyclerView. At Google IOGoogle introduced the RecyclerView widget - an entirely updated approach to showing a collection of data. RecyclerView was designed to be more flexible and extendable than its predecessor, ListView. While most of what RecyclerView offers is an improvement over the existing functionality of ListViewthere are a few notable features missing from the RecyclerView API.

Adapter s for expanding and collapsing groups to bring back some of the former glory of ExpandableListView. To understand this library is to understand RecyclerView. According to the docs:. In other words, the adapter is just the middleman: translating indexes from boundaries and the james theorem backing data structure, to views to be passed along to a RecyclerView to be seen on screen.

Android ExpandableListView Example Tutorial

When you are showing a single dimensional list of objects, this translation is simple. The indexes of the objects in the backing data set directly correspond to the indexes of views displayed on screen. But when you want to display two dimensional data, like in case of an expandable list, this translation gets a bit more tricky. When the indexes of the views are the same as those of the backing data set, there is only a single truth to maintain. But when those indexes become disparate, so does the source of truth, leaving you with two possible truths.

Me too. Above is music app showing a list of Genre s with corresponding Artist s. The numbers to the left of the phones represent the view indexes. As you can see both phones contain 9 row items. But if you look at row 6, you will see the data on each phone is different. On the left, view index 6 equals the Genre object, Classic while on the right it equals the Artist object, Miles Davis. Enter the double source of truth problem. The view indexes truth numero uno are different from the backing data structure indexes truth numero dos.

The RecyclerView.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. 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. 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.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. Active Oldest Votes. Shweta Chauhan Shweta Chauhan 4, 3 3 gold badges 21 21 silver badges 42 42 bronze badges. Umasankar : I think whole code is here.

If you update result screenshot Image above, it may look cool! Anyone can explain to me what is going on in the code? SimpleGroupViewHolder parent. Ali mohammadi Ali mohammadi 13 13 silver badges 22 22 bronze badges. Gustavo Gustavo 4, 4 4 gold badges 28 28 silver badges 60 60 bronze badges.

Pushpendra Pushpendra 2, 4 4 gold badges 18 18 silver badges 43 43 bronze badges. Spartan, I checked their example but found it hard to follow. What do I need to add to the project to start using their extended library? Is there anything else other than the compile directory, do I need to copy any lib files to my project? Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown.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.

Expandable RecyclerView

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:. Now you can add the RecyclerView to your layout file.It contains two views one is parent view and other is child view.

Parent is visible by default but the child view has to be expanded and collapsed. It will expand when we click on parent view. This feature is quite similar to the ExpandableListView in Android. Since it is an old one, it does not perform well according to our requirement. After adding the library, we have to add some Java classes with the help of this library like Adapter, Model, and View holders. So here in this example we will show Movie category as a parent and movies according to the category are a child.

Create this XML file for creating the view of movie category. Add the code inside LinearLayout. Create this class and extend it with ParentViewHolder. It is a class which binds the view. Here we take the reference of MovieCategory view and set the properties when it is expanded and collapsed.

Now, set the properties for expand and collapse of arrow image and its rotation accordingly by implementing two methods setExpanded and onExpansionToggled.

Create this custom Adapter class which extends ExpandableRecyclerAdapter. One of which is for parent and the other for the child. It is in our Main Activity that we pass the data, set the adapter and take the reference of Recycler View.

Using ExpandableTextView library in Android Studio

We can save the expanded and collapsed state of items in our Recycler View during our device configuration changes. Other things and also we can store the state of same. Like this, we can save the state. This feature is mainly used in many applications. We can customize it according to the requirement.

It is the same as ExapandableListView but has some new features added. An interesting functionality of Android, it is frequently used by the developers.

Android ExpandableListview. HEY thats nice tutorial but can u explain me how do i get the child position in the fragments class and how to make like only one to be expandable if i have 3 views i need only one among them to be opened first please help me put.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.

expandable recyclerview android

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.

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.

expandable recyclerview android

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.

A LayoutManager is responsible for measuring and positioning item views within a RecyclerView as well as determining the policy for when to recycle item views that are no longer visible to the user.

LayoutParams subclass for children of RecyclerView. A Listener interface that can be attached to a RecylcerView to get notified whenever a ViewHolder is attached to or detached from RecyclerView. An OnItemTouchListener allows the application to intercept touch events in progress at the view hierarchy level of the RecyclerView before those touch events are considered for RecyclerView's own scrolling behavior. A RecyclerListener can be set on a RecyclerView to receive messages whenever a view is recycled.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.

Expandable RecyclerView Android – RecyclerView with Expandable 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.

expandable recyclerview android

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. 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. Please ensure that you have set the ExpandableListView in the xml layout and have initialised it in your activity properly using findViewById.

Thanks a lot for your article. How to add a child after last child position of group?


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