Recyclerview kotlin

Get unlimited access to all video courses and books on this site with the new raywenderlich. Darryl Bayliss wrote the original and Rod Biresch provided the original update. Recycling is good for the planet. Applying this concept to development, Android engineers realized recycling can also make an OS run efficiently.

The result? Recycling enthusiasts and developers alike rejoiced at the release of the RecyclerView widget for Android Lollipop. Google announced a support library to make this clean, green recycling machine backwards compatible all the way to Android Eclair 2. More celebration! Ready to blast off?

Review our introductory tutorials for a refresher! Get the starter project using the Download Materials at the top or bottom of this tutorial and open it in Android Studio. To get a key, put your name and email address into api. Next, copy the API key and open the strings. Consider the next section your mission brief.

Android used to use ListView or GridView classes for displaying lists. However, in a RecyclerView, there are features that separate your code into maintainable components even as they enforce memory-efficient design patterns. How could it be better than the tried and tested ListView and GridView? The answers are in the details.

You create a row layout for the items and use that layout inside your adapter. You inflate your item layout in getViewreferencing each view with the unique ID you provided in XML to customize and add view logic. Or is it? ListViews and GridViews only do half the job of achieving true memory efficiency.

All this calling around can become processor-intensive, especially for complicated layouts. Furthermore, the situation can cause your ListView scrolling to become jerky or nonresponsive as it tries to grab view references.

Android initially provided a solution to this problem on the Android Developers site with smooth scrolling via the power of the View Holder pattern. With this pattern, a class becomes an in-memory reference to all the views needed to fill your layout.A android. ViewGroup that shows items in a horizontal scrolling list. ViewGroup that shows items in a vertically scrolling list. A flexible view for providing a limited window into a large data set. Glossary of terms: Adapter: A subclass of Adapter responsible for providing views that represent items in a data set.

Position: The position of a data item within an Adapter. 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. Positions in RecyclerView:. RecyclerView introduces an additional level of abstraction between the Adapter and 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:. 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 5th element, you should use these methods as they'll match what user is seeing. Beware that these methods may not be able to calculate adapter positions if Adapter notifyDataSetChanged has been called and new layout has not yet been calculated.

recyclerview kotlin

When writing a LayoutManager you almost always want to use layout positions whereas when writing an Adapteryou probably want to use adapter positions. The best part of this approach is that it extends to any arbitrary changes - item updates, moves, addition and removal can all be computed and handled the same way. Though you do have to keep two copies of the list in memory while diffing, and must avoid mutating them, it's possible to share unmodified elements between list versions.

There are three primary ways to do this for RecyclerView. We recommend you start with ListAdapterthe higher-level API that builds in List diffing on a background thread, with minimal code.

AsyncListDiffer also provides this behavior, but without defining an Adapter to subclass. Each approach allows you to specify how diffs should be computed based on item data. Observer base class for watching changes to an 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.

An implementation of RecyclerView. OnItemTouchListener that has empty method bodies and default return values.If you are an android developer you already familiar RecyclerView.

recyclerview kotlin

When you need to show scrolling list based on large data set, you should use RecyclerView. RecyclerView is a flexible and upgraded version of ListView. In the RecyclerView several different works together to display your data. Basically, RecyclerView works on ViewHolder design pattern. Each row managed by ViewHolder. So you can say, each view holder is in responsible for displaying a single item with a view.

It contains ImageView for use image and TextViews for the display name and email.

RecyclerView Kotlin Tutorial

In this dagger module, we are providing Retrofit client and User Service using provide annotation. In this class, we using fetching user list from a remote server and updating ViewModel value. Basically, In this class, I observing ViewModel and based on changes.

I update the adapter list. Apart from this, I refresh value on pull to refresh using SwipeRefreshLayout component. Android RecyclerView Example in Java.

Open the MainActvitiy layout file and paste below code. RecyclerView for showing user list. AppCompatTextView for showing an error message. ProgressBar for showing loader while getting data from a remote server. SwipeRefreshLayout as a root view for refreshing list item on pull to refresh. I need to write a data model to parse that JSON.

Android RecyclerView Tutorial with Kotlin

Prepare an XML layout for showing list user list item. Create a RecyclerView Adapter that holds that holds user item. For the above layout creates a RecycleView holder adapter that holds the user list item package com. LayoutInflater import android. View import android. ViewGroup import androidx.

RecyclerView import com.Learning the small things will help you to migrate to Kotlin. So lets see this Kotlin RecyclerView Example. If you are having any confusions and queries then lets discuss it on the comment section. And I will keep posting more tutorials using Android Development with Kotlin as well. The passion of teaching made me create this blog. Thank you for posting this tutorial for us, I have some doubt for example When we take kotlin file or class i am little bit confused kindly help me to understand.

What is the difference between normal recyclerview and Kotlin Recyclerview?? Please Give me Description. I am new to Android development and wanted to experiment with some already written code. I downloaded the code and tried to make it work on Android Studio 3. Thank you! I can not find this but with a search engine in the nav bar … would you have something like that? Exellent example, the best. Any chance for a tutorial converting this one to image and text recyclerview?

It would be nice to be able to change this to whatever we want,and have it as template. A really good example, I implemented en androidStudio 4.

The minSdkVersion is 21 5. Save my name, email, and website in this browser for the next time I comment. Belal Khan. Can we have the complete source code?

Source code is in the video description, check out the video tutorial of this post in youtube. No difference basically. Can you port the code to work on the recent android studio. ClassNotFoundException: Reply. Thanks Reply. Thanks in advance Luis. RecyclerView import android. LayoutInflater import android. View import android. ViewGroup import android. AppCompatActivity import android.

Bundle import android.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.

Android RecyclerView in Fragment (Kotlin)

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:.

Now you can add the RecyclerView to your layout file. For example, the following layout uses RecyclerView as the only view for the whole layout:. Once you have added a RecyclerView widget to your layout, obtain a handle to the object, connect it to a layout manager, and attach an adapter for the data to be displayed:.

Note: With Android Studio 3. Consider using view binding instead of findViewById.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. ClickListener " right. You can implement your click listeners inside your adapter instead of implementing gesture detector to get child views.

I've added sample code that you can see how to implement that:. Learn more. Asked 27 days ago. Active 27 days ago. Viewed 85 times. ClickListener " right how can i do it to override ClickListener interface methods? Yousef Awad Yousef Awad 1.

Why you implementing it with touch listener? Active Oldest Votes. I've added sample code that you can see how to implement that: class YourAdapter: RecyclerView. Saman Sattari Saman Sattari 1, 4 4 gold badges 18 18 silver badges 30 30 bronze badges. YousefAwad this is a better aproach and also best practise. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.

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Related Hot Network Questions. Question feed. Stack Overflow works best with JavaScript enabled.Our consultant, Sirry, was very helpful and responsive. She communicated well and with his prior to our arrival and when we arrived at our first destination everything was well arranged and ran very smoothly - the transfers, the hotels, the ferries, the car hire.

Recyclerview - Multiple View Types - Kotlin/Firestore

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recyclerview kotlin

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