Recyclerview swap items

The RecyclerView is a ViewGroup that renders any adapter-based view in a similar way.

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It is supposed to be the successor of ListView and GridView. One of the reasons is that RecyclerView has a more extensible framework, especially since it provides the ability to implement both horizontal and vertical layouts. Use the RecyclerView widget when you have data collections whose elements change at runtime based on user action or network events. Furthermore, it provides animation support for RecyclerView items whenever they are added or removed, which had been extremely difficult to do with ListView.

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RecyclerView also begins to enforce the ViewHolder pattern too, which was already a recommended practice but now deeply integrated with this new framework. For more details, see this detailed overview. RecyclerView differs from its predecessor ListView primarily because of the following features:. A RecyclerView needs to have a layout manager and an adapter to be instantiated. A layout manager positions item views inside a RecyclerView and determines when to reuse item views that are no longer visible to the user.

recyclerview swap items

RecyclerView provides these built-in layout managers:. To create a custom layout manager, extend the RecyclerView. LayoutManager class. Here is Dave Smith's talk on the custom layout manager. RecyclerView includes a new kind of adapter. You will have to override two main methods: one to inflate the view and its view holder, and another one to bind data to the view.

The good thing about this is that the first method is called only when we really need to create a new view.

DefaultItemAnimator can be used for basic default animations and works quite well. See the section of this guide for more information. Every RecyclerView is backed by a source for data.

In this case, we will define a Contact class which represents the data model being displayed by the RecyclerView:. Now the RecyclerView is embedded within our activity layout file. Next, we can define the layout for each item within our list. Before we create the adapter, let's define the XML layout file that will be used for each row within the list.Item drag and drop of RecylerView is the very cool feature in android.

Drag and drop feature is the inbuilt feature of RecylerView. There are many external libraries are available to drag and drop item and swipe item position. But in this tutorial, I am explaining how to implement this awesome feature of RecylerViewwhich is inbuilt in RecylerView? RecylerView provides ItemThouchhelper class to drag and drop.

recyclerview swap items

ItemTouchHelper is the best utility that helps to drag and drop item smoothly. It provides many features like swipe item and restricted target to drop an item, awesome animation and much more. A clickable item view should be the selectable background color and after dismissed, it should be unselected. So these three listeners are required for action. Let me create three listeners first then after we will see how and where we need to implement those?

RecyclerVew provides the awesome inbuilt feature to handle all this request. Here is the source code link for drag and drop item recyclerView in android. I am a very enthusiastic Android developer to build solid Android apps.

I have a keen interest in developing for Android and have published apps to the Google Play Store. I always open to learning new technologies. For any help drop us a line anytime at contact mobologicplus. This site uses Akismet to reduce spam. Learn how your comment data is processed. Hi, I like your post. But in this post suppose we use number like 1,2,3 and so on instead of image, then if we drag the itemnumber is not updated.

You made some respectable points there. I seemed on the internet for the issue and found most people will go along with together with your website. Sharing is caring! Share Tweet Pin LinkedIn. UP ItemTouchHelper. ViewHolder viewHolder, RecyclerView. DOWN. END. ViewHolder viewHolder. ViewHolder viewHolder. ViewHolder implements View. VHItem viewHolder. Override public void onStartDrag RecyclerView. Sunil Gupta.Very simple solution to create swipe menu with RecyclerView without any additional libraries — using ItemTouchHelper Callback for swiping items and ItemDecoration for drawing on canvas.

Code from this tutorial is available on my github. To do this, we need to download some data eg. If you are familiar with RecyclerView just go to the second chapter. Before we start to implement RecyclerView we need to add few dependencies into the project:.

Adapter for RecyclerView is the most important class here. We need to override 3 methods to make things works:. In our example, we read CSV database and pass it into an adapter. Proper work of RecyclerView needs setting up two things: first — is mentioned above adapter, second — layout manager, it tells view how to display data. Here we use LinearLayout.

OK, so we want to add some actions to our static view. Using ItemTouchHelper Callback we need to implement three methods to make this work. Next, we need to attach helper to RecyclerView. Now swipe should be enabled in our project. Of course, as you have noticed, we are able to swipe out the items — we have to block it somehow. OK, so where the swipeBack came from? We just need to set onTouchListener on RecyclerView — and after finishing swiping we set swipeBack to true:.

To be honest, this is the most important part in here and most difficult to explain, so I decided to move it into the separate chapter. First, create properties buttonShowedState to keep information about what kind of button has been shown— if any. We need some condition to set properly our state — in our touch listener we check how much to the left or right user swiped the item.

If enough, we change state to show buttons:. Why simulate?

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Because we could already have onclick listener on items, so we need to disable it because of glitches. So what happens here? After user clicks on RecyclerView we just reset state of our SwipeController and redraw everything back. We have access to canvas in onChildDraw method so we can use it here. We need to assign buttonInstance property for future usage.But one thing missing in that is adding swipe to delete and undo functionalities as gmail does. In this article we are going to add swipe to delete and undo options in a recycler view.

Instead of continuing that article, we are going to start a fresh project to make it simpler to understand. You can see an empty row displayed on swiping the row. You have to take care of refreshing the list by removing the item from the adapter dataset. SimpleCallback provides certain callback methods like onMoveonChildDrawonSwiped when the row is swiped.

Showing the background view, removing the item from adapter can be done using these callback methods. Below is the code snipped of ItemTouchHelper and attaching it to recycler view. This code has to be bit modified in order to make the swipe and undo works.

The swipe directions can be decided while creating the SimpleCallback. If you want other directions, you can combine with operator. Planning the layout is very important while adding background view of the row. Lot of people are providing the background by drawing the view on a Canvas in onChildDraw method.

This will be a tedious process drawing it on a canvas if the background view complex. Design the same in an xml layout is much easier. So I have placed both the foreground and background views in a simple layout using FrameLayout keeping the foreground layout on top.

The foreground view will be always visible in the recycler view, and when swipe is performed the background will be visible staying in a static position. I have created an example JSON that contains restaurant menu with proper names and images. We are going to consume this json to display the food items in our RecyclerView list.

Note: This project is developed using Android Studio 3. In order to get this article working, get the latest the version of Android Studio here. Open build. Add the below resources to your strings. Open styles. This make the text to darker as we have white background to toolbar. Create a class named MyApplication. This is a singleton class used to initiate the volley library. Open AndroidManifest. Now we have all the resources ready.

Open layout file your MainActivity. Create a class named Item. This POJO class contains menu item namepricedescription and url of thumbnail image. This layout file renders each row in recycler view using the adapter class. Here we are adding an ImageView for thumbnail and few TextViews to display the menu item namedescription and price.

Create a class named CartListAdapter. This adapter class will be used to inflate the layouts with proper data in recycler view. Now we are at the core part of this article i.To understand how RecyclerView works in a typical application, this topic explores the RecyclerViewer sample app, a simple code example that uses RecyclerView to display a large collection of photos:.

Because of RecyclerView 's performance advantages, this sample app is able to quickly scroll through a large collection of photos smoothly and without noticeable delays. In this example app, a "photo album" data source represented by the PhotoAlbum class supplies RecyclerView with item content.

PhotoAlbum is a collection of photos with captions; when you instantiate it, you get a ready-made collection of 32 photos:. The collection of photos is organized such that each photo can be accessed by an indexer.

A Basic RecyclerView Example

For example, the following lines of code access the image resource ID and caption for the tenth photo in the collection:. PhotoAlbum also provides a RandomSwap method that you can call to swap the first photo in the collection with a randomly-chosen photo elsewhere in the collection:. Because the implementation details of PhotoAlbum are not relevant to understanding RecyclerViewthe PhotoAlbum source code is not presented here.

The source code to PhotoAlbum is available at PhotoAlbum. The layout file, Main. Note that you must use the fully-qualified name android. RecyclerView because RecyclerView is packaged in a support library. The OnCreate method of MainActivity initializes this layout, instantiates the adapter, and prepares the underlying data source:. Passes the photo album data source to the constructor of the adapter, PhotoAlbumAdapter which is defined later in this guide. Note that it is considered a best practice to pass the data source as a parameter to the constructor of the adapter.

Each item in the RecyclerView is made up of a CardView that contains a photo image and photo caption details are covered in the View Holder section below. The predefined LinearLayoutManager is used to lay out each CardView in a vertical scrolling arrangement:.

Extending the RecyclerView Example

This code resides in the main activity's OnCreate method. The constructor to the layout manager requires a contextso the MainActivity is passed using this as seen above. Instead of using the predefined LinearLayoutManageryou can plug in a custom layout manager that displays two CardView items side-by-side, implementing a page-turning animation effect to traverse through the collection of photos.

Later in this guide, you will see an example of how to modify the layout by swapping in a different layout manager. The view holder class is called PhotoViewHolder. PhotoViewHolder derives from RecyclerView.

Android swipe menu with RecyclerView

ViewHolder and contains properties to store references to the ImageView and TextView shown in the above layout. PhotoViewHolder consists of two properties and one constructor:.

Note that you always forward the parent item view to the base constructor. The adapter later retrieves view references from these properties when it updates this CardView 's child views with new data.

For more information about RecyclerView. ViewHoldersee the RecyclerView. ViewHolder class reference. The adapter loads each RecyclerView row with data for a particular photograph. For a given photograph at row position Pfor example, the adapter locates the associated data at position P within the data source and copies this data to the row item at position P in the RecyclerView collection.

recyclerview swap items

The adapter uses the view holder to lookup the references for the ImageView and TextView at that position so it doesn't have to repeatedly call FindViewById for those views as the user scrolls through the photograph collection and reuses views. In RecyclerVieweran adapter class is derived from RecyclerView.The basic app described in A Basic RecyclerView Example actually doesn't do much — it simply scrolls and displays a fixed list of photograph items to facilitate browsing.

In real-world applications, users expect to be able to interact with the app by tapping items in the display. Also, the underlying data source can change or be changed by the appand the contents of the display must remain consistent with these changes.

In the following sections, you'll learn how to handle item-click events and update RecyclerView when the underlying data source changes. When a user touches an item in the RecyclerViewan item-click event is generated to notify the app as to which item was touched. This event is not generated by RecyclerView — instead, the item view which is wrapped in the view holder detects touches and reports these touches as click events.

To illustrate how to handle item-click events, the following steps explain how the basic photo-viewing app is modified to report which photograph had been touched by the user.

When an item-click event occurs in the sample app, the following sequence takes place:. The adapter forwards the event with item position information to the activity's item-click handler. Next, an item-click event handler method is added to MainActivity. This handler briefly displays a toast that indicates which photograph item was touched:. A good place to do this is immediately after PhotoAlbumAdapter is created:.

In this basic example, handler registration takes place in the main activity's OnCreate method, but a production app might register the handler in OnResume and unregister it in OnPause — see Activity Lifecycle for more information. The next step is to create a handler in the adapter that raises this ItemClick event. The following method, OnClickis added immediately after the adapter's ItemCount method:.

This OnClick method is the adapter's listener for item-click events from item views. Before this listener can be registered with an item view via the item view's view holderthe PhotoViewHolder constructor must be modified to accept this method as an additional argument, and register OnClick with the item view Click event. Here's the modified PhotoViewHolder constructor:. The itemView parameter contains a reference to the CardView that was touched by the user.

Note that the view holder base class knows the layout position of the item CardView that it represents via the LayoutPosition propertyand this position is passed to the adapter's OnClick method when an item-click event takes place. The adapter's OnCreateViewHolder method is modified to pass the adapter's OnClick method to the view-holder's constructor:. Now when you build and run the sample photo-viewing app, tapping a photo in the display will cause a toast to appear that reports which photograph was touched:.

This example demonstrates just one approach for implementing event handlers with RecyclerView. Another approach that could be used here is to place events on the view holder and have the adapter subscribe to these events.

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If the sample photo app provided a photo editing capability, separate events would be required for the ImageView and the TextView within each CardView : touches on the TextView would launch an EditView dialog that lets the user edit the caption, and touches on the ImageView would launch a photo touchup tool that lets the user crop or rotate the photo. Depending on the needs of your app, you must design the best approach for handling and responding to touch events.

To demonstrate how RecyclerView can be updated when the data set changes, the sample photo-viewing app can be modified to randomly pick a photo in the data source and swap it with the first photo. First, a Random Pick button is added to the example photo app's Main.

Next, code is added at the end of the main activity's OnCreate method to locate the Random Pick button in the layout and attach a handler to it:. This handler calls the photo album's RandomSwap method when the Random Pick button is tapped. The RandomSwap method randomly swaps a photo with the first photo in the data source, then returns the index of the randomly-swapped photo.

When you compile and run the sample app with this code, tapping the Random Pick button does not result in a display change because the RecyclerView is not aware of the change to the data source.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.

Swipe gestures in Recycler View - Android

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.


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