Picasso is a image loading library by Square Inc. It makes image loading easier. It also provides disk caching and makes networking easier.
For example if you are using Picasso in a adapter it loads image only once and reuses the cached image for the next time. Here I have created a Android Studio project with package com.
You can download the complete project as zip or fork from our Github repository. The next layout is for RecylerView list item. It has a TextView and ImageView child widgets to display android version name and android version image. It has getter and setter methods. The adapter also binds the view holders to their data. That class has two fields or properties: name and image. Those fields are private hence cannot be accessed by outside classes. So then how do we assign them values, or even get their values?
Instantiating the Movie class will cause the instantiater to pass us the name and image via constructor. Then the getter methods can return us the name and image. We will now come and create a simple interface that will act as the signature for our LongClickListener. Remember we are interested in listening to long click events for our RecyclerView.
The onItemLongClick will be taking a View object and an integer, the position of the clicked item. Hence the implementer of the interface will have to provide their implementations. You can see our MyHolder class is extending the RecycerView. ViewHolder class. This will make our class a view holder class. A view holder class is a class responsible for temporarily holding widgets for the adapter to recycle those views.
This dramatically improves performance as inflation then occurs only once. Then subsequently the widgets are recycled. Deriving from that class has forced us to provide a constructor that takes a View object and passing it to the super class.
OnLongClickListener interface. That is the interface that normally has to be implemented suppose you want ti listen to long click events of any view. Then we have our Adapter class as well. As our RecycerView adapter class, this class has to derive from RecyclerView. Our MyAdapter class is our adapter class.
In this case we specifically use the RecyclerView. Those method include the getCount which will return the number of movies to be displayed in our recyclerview. Then onCreateViewHolder is where we inflate our model layout into a view object. The inflater view has then been passed to the MyHolder , Eventually that method returns the MyHolder instance.
Then onBindViewHolder is where we bind data. First our View holder is passed to us to allow us to reference the various widgets it is holding.
In our case those widgets are an imageview and a textview. In our case we simply show a toast message when our recyclerview item is long clicked. Then we come to our MainActivity. This class is deriving from our AppCompatActivity. This class is our launcher activity. It is introduced in Marshmallow.
It is an advanced version of the ListView with improved performance and other benefits. RecyclerView is mostly used to design the user interface with the fine-grain control over the lists and grids of android application.
In this tutorial, we will create a list of items with ImageView for the icon and TextView for description using RecyclerView and performs click listener on the item of its list. Create an Android project, and add the RecyclerView support library com. Create a border. Create a MyListData. This class is used as POJO class which sets the properties of the items. Create a MyListAdapter. This class extends RecyclerView. Adapter class and override its unimplemented methods.
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:. This code resides in the main activity's OnCreate method. The constructor to the layout manager requires a context , so the MainActivity is passed using this as seen above. Instead of using the predefined LinearLayoutManager , you 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. 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. Handling keyboard input.
Supporting game controllers. Input method editors. Performing network operations. Transmit network data using Volley. Perform network operations using Cronet. Transferring data without draining the battery.
Reduce network battery drain. Transfer data using Sync Adapters. Bluetooth Low Energy. Wi-Fi infrastructure. Discover and connect. Runtime API reference. Web-based content. Android App Bundles. Google Play. Play Asset Delivery. Play Feature Delivery. In-app reviews. In-app updates. Google Play Instant. Get started with instant apps. Get started with instant games. Integrate with Firebase. Play Install Referrer. Play Install Referrer Library.
Application Licensing. Android GPU Inspector. System profiling. Analyze a system profile. GPU performance counters. Frame profiling. Analyze a frame profile. Frame Profiler UI. Customize or port game engines. Process input events. Support game controllers. Achieve proper frame pacing. Frame pacing in Vulkan. Integrate Android Performance Tuner. Output audio. Manage memory. Use prebuilt or turnkey game engines. Develop with Defold. Develop with Godot. Develop with Unity.
0コメント