retrofit server lcd panel free sample
Retrofit is a type-safe HTTP networking library used for Android and Java. Retrofit was even better since it was super fast, offered better functionality, and even simpler syntax. Most developers since then have switched to using Retrofit to make API requests.
Open Android Studio and Start a new Android Studio Project -> Empty Activity. Let us name the project MarvelRetrofit. Select Finish and wait for the project to build.
implementation "com.squareup.retrofit2:retrofit:2.7.2"implementation "com.squareup.retrofit2:converter-gson:2.7.2"implementation "com.squareup.okhttp3:okhttp:3.6.0"
public class RetrofitClient {private static RetrofitClient instance = null;private Api myApi;private RetrofitClient() {Retrofit retrofit = new Retrofit.Builder().baseUrl(Api.BASE_URL).addConverterFactory(GsonConverterFactory.create()).build();myApi = retrofit.create(Api.class);}public static synchronized RetrofitClient getInstance() {if (instance == null) {instance = new RetrofitClient();}return instance;}public Api getMyApi() {return myApi;}}
public class MainActivity extends AppCompatActivity {ListView superListView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);superListView = findViewById(R.id.superListView);getSuperHeroes();}private void getSuperHeroes() {Call
We have learned that networking is a crucial factor in mobile application development. We have learned how to use Retrofit and its advantages and disadvantages. Did you know that Retrofit takes 312ms to carry out one discussion? That is super fast.
Check out other ways to use Retrofit in their official documentation. You can access this tutorial’s code on GitHub. You can also download the sample APK on Google Drive.
In Android, Retrofitis a REST Client for Java and Android by Square inc under Apache 2.0 license. Its a simple network library that used for network transactions. By using this library we can seamlessly capture JSON response from web service/web API. It’s easy and fast library to retrieve and upload the data(JSON or any other structured data) via a REST based web service.
We have a lot of network libraries that used to fetch and send the data from/to server. In our previous article we use Volley library for network transactions but Retrofitis an ultimate replacement of Volley and all other libraries. Retrofitis better alternative of other libraries in terms of performance, ease of use, extensibility and others.
In Android, retrofit library is different from other network libraries because it gives us an easy to use platform through which we don’t need to parse JSON responses as they are done by library itself. It used GSON library in the background to parser the response data. What we need to do is define a POJO (Plain Old Java Object) to parse the response.
Below is the example of Retrofit in which we have implement the POST type request. In this we are implementing sign up api. In this example firstly we create sign up page design with 3 EditText name, email and password and one sign up Button. After that in our MainActivity we are getting our EditText and Button and on click of sign up Button the data in EditText is validate and then we are implementing signup api to save the data in our database. After getting response from api we are displaying the message on the screen by using a Toast.
Below is the example of Retrofit in which we have implement the GET type request. In this we are displaying a list of items by using RecyclerView. Firstly we declare a RecyclerView in our XML file and then get the reference of it in our Activity. After that we create POJO Class, API Interface, Rest Adapter and then implement the API in our onCreate method of MainActivity. After getting the success response from server we are calling our adapter to set the data in RecyclerView.
In this step Firstly we get the reference of RecyclerView in our Activity. After that we implement the API in our onCreate method. Finally After getting the success response from server we are calling our adapter to set the data in RecyclerView. In this step we show a Progress dialog while implementing API and after getting response or error we dismiss it.
3. setEndpoint and baseUrl method – In Retrofit 1.9, the setEndpoint(String url) method defines the API’s base url but in 2.x baseUrl(API_BASE_URL) is used to set the base url.
4. Dynamic Urls – One of the best feature in retrofit 2.x is dynamic urls. Lets take a use-case, we need to download file from internet source and files will have different urls. The files are either stored on Amazon;s S3 server or somewhere else on the web. So the main problem in 1.9 is we need to create RestAdapter with base url every time we wanted to load a file but in 2.x we can use dynamic urls, for implementing it we can leave the HTTP verb annotation empty and use the @url annotation as a parameter of method. Retrofit will automatically map the provided url string and do the job for us.
6. Creating the Retrofit Instance: For network requests with Retrofit we need to create instance using retrofit builder class and then configure it with base URL. Suppose we have to implement login API then we need to build retrofit instance, setting base url and create connection between our retrofit instance and API Interface. For this, its better to create a class in which we have a method that create the connection and then returns the API Interface object. You can create this Retrofit instance where you want to implement API but its better to create a common class/method and use it where you want.
Below is the example of Retrofit 2.x in which we have implement the POST type request. In this we are implementing sign up api. In this example firstly we create sign up page design with 3 EditText name, email and password and one sign up Button. After that in our MainActivity we are getting our EditText and Button and on click of sign up Button the data in EditText is validate and then we are implementing signup api to save the data in our database. After getting response from api we are displaying the message on the screen by using a Toast.
In this step we create a new class to set the Retrofit. In this class getClient method returns the Api Interface class object which we are using in our MainActivity.
Below is the example of Retrofit 2.x in which we have implement the GET type request. In this we are displaying a list of items by using RecyclerView. Firstly we declare a RecyclerView in our XML file and then get the reference of it in our Activity. After that we create POJO Class, API Interface, Retrofit builder and then implement the API in our onCreate method of MainActivity. After getting the success response from server we are calling our adapter to set the data in RecyclerView.
In this step we create a new class to set the Retrofit builder. In this class getClient method returns the Api Interface class object which we are using in our MainActivity.
In this step Firstly we get the reference of RecyclerView in our Activity. After that we implement the API in our onCreate method. Finally After getting the success response from server we are calling our adapter to set the data in RecyclerView. In this step we show a Progress dialog while implementing API and after getting response or error we dismiss it.
Neatly explained. It is great help to learn concept of retrofit networking library as well as, well explained difference in between retrofit and other network library.
In this blog post of our Retrofit launch sequence we"ll show you one of the most requested topics: how to download files. We"ll give you all the insight and snippets you need to use Retrofit to download everything, from tiny .png"s to large .zip files.
If you"re reading this and you haven"t written code for any Retrofit requests yet, please check our previous blog posts to get started. For all you Retrofit experts: the request declaration for downloading files looks almost like any other request:
If the file you want to download is a static resource (always at the same spot on the server) and on the server your base URL refers to, you can use option 1. As you can see, it looks like a regular Retrofit 2 request declaration. Please note, that we"re specifying ResponseBody as return type. You should not use anything else here, otherwise Retrofit will try to parse and convert it, which doesn"t make sense when you"re downloading a file.
The second option is new to Retrofit 2. You can now easily pass a dynamic value as full URL to the request call. This can be especially helpful when downloading files, which are dependent of a parameter, user or time. You can build the URL during runtime and request the exact file without any hacks. If you haven"t worked with dynamic URLs yet, feel free to head over to our blog post for that topic: dynamic urls in Retrofit 2
If you"re confused by the ServiceGenerator.create(), head over to our first blog post to get started. Once we"ve created the service, we"ll make the request just like any other Retrofit call!
Most of it is just regular Java I/O boilerplate. You might need to adjust the first line on where and with what name your file is being saved. When you have done that, you"re ready to download files with Retrofit!
But we"re not completely ready for all files yet. There is one major issue: by default, Retrofit puts the entire server response into memory before processing the result. This works fine for some JSON or XML responses, but large files can easily cause Out-of-Memory-Errors.
If you’re downloading a large file, Retrofit would try to move the entire file into memory. In order to avoid that, we"ve to add a special annotation to the request declaration:
You can still use the same writeResponseBodyToDisk() method. If you remember the @Streaming declaration and this snippet, you can download even large files with Retrofit efficiently.
All modern Android apps need to do network requests. Retrofit offers you an extremely convenient way of creating and managing network requests. From asynchronous execution on a background thread, to automatic conversion of server responses to Java objects, Retrofit does almost everything for you. Once you"ve a deep understanding of Retrofit, writing complex requests (e.g., OAuth authentication) will be done in a few minutes.
Invest time to fully understand Retrofit"s principles. It"ll pay off multiple times in the future! Our book offers you a fast and easy way to get a full overview over Retrofit. You"ll learn how to create effective REST clients on Android in every detail.
Retrofit is a REST Client for Java and Android. This library, in my opinion, is the most important one to learn, as it will do the main job. It makes it relatively easy to retrieve and upload JSON (or other structured data) via a REST based webservice.
In Retrofit you configure which converter is used for the data serialization. Typically to serialize and deserialize objects to and from JSON you use an open-source Java library — Gson. Also if you need, you can add custom converters to Retrofit to process XML or other protocols.
For making HTTP requests Retrofit uses the OkHttp library. OkHttp is a pure HTTP/SPDY client responsible for any low-level network operations, caching, requests and responses manipulation. In contrast, Retrofit is a high-level REST abstraction build on top of OkHttp. Retrofit is strongly coupled with OkHttp and makes intensive use of it.
Now that you know that everything is closely related, we are going to use all these 3 libraries at once. Our first goal is to get all the cryptocurrencies list using Retrofit from the Internet. We will use a special OkHttp interceptor class for CoinMarketCap API authentication when making a call to the server. We will get back a JSON data result and then convert it using the Gson library.
When learning something new, I like to try it out in practice as soon as I can. We will apply a similar approach with Retrofit 2 for you to understand it better more quickly. Don’t worry right now about code quality or any programming principles or optimizations — we’ll just write some code to make Retrofit 2 work in our project and discuss what it does.
We are going to execute HTTP requests on a server accessible via the Internet. Give this permission by adding these lines to your Manifest file:
Find the latest Retrofit version. Also you should know that Retrofit doesn’t ship with an integrated JSON converter. Since we will get responses in JSON format, we need to include the converter manually in the dependencies too. We are going to use latest Google’s JSON converter Gson version. Let’s add these lines to your gradle file:// 3rd party
As you noticed from my comment, the OkHttp dependency is already shipped with the Retrofit 2 dependency. Versions is just a separate gradle file for convenience:def versions = [:]
Ok after a quick experiment, it is time to bring this Retrofit implementation to the next level. We already got the data successfully but not correctly. We are missing the states like loading, error and success. Our code is mixed without separation of concerns. It’s a common mistake to write all your code in an activity or a fragment. Our activity class is UI based and should only contain logic that handles UI and operating system interactions.
The first step to improve was to start using Dependency Injection. Remember from the previous part we already have Dagger 2 implemented inside the project correctly. So I used it for the Retrofit setup./**
As you may have noticed while creating the Retrofit builder instance, we added a special Retrofit calls adapter using addCallAdapterFactory. By default, Retrofit returns a Call
Instead of communicating with our Retrofit implementation directly, we are going to use Repository for that. For each kind of entity, we are going to have a separate Repository./**
If the app is freshly installed and it is its first launch, then there will not be any data stored inside the local database. Because there is no data to show, a loading progress bar UI will be shown. Meanwhile the app is going to make a request call to the server via a web service to get all the cryptocurrencies list.
Another class used in our Repository and LiveDataCallAdapter where all the "magic" happens is ApiResponse. Actually ApiResponse is just a simple common wrapper around the Retrofit2.Response class that converts each response to an instance of LiveData./**
Inside this wrapper class, if our response has an error, we use the Gson library to convert the error to a JSON object. However, if the response was successful, then the Gson converter for JSON to POJO object mapping is used. We already added it when creating the retrofit builder instance with GsonConverterFactory inside the Dagger AppModule function provideApiService.
Because we want to use the networking library OkHttp in our project for all network operations, we need to include the specific Glide integration for it instead of the default one. Also since Glide is going to perform a network request to load images via the internet, we need to include the permission INTERNET in our AndroidManifest.xml file — but we already did that with the Retrofit setup.
So we are going to use coroutines everywhere in this app where we need to wait until a result is available from a long-running task and than continue execution. Let’s see one exact implementation for our ViewModel where we will retry getting the latest data from the server for our cryptocurrencies presented on the main screen.
The idea of all this code is that we can combine multiple calls to form nice-looking sequential code. First we request to get the ids of the cryptocurrencies we own from the local database and wait for the response. Only after we get it do we use the response ids to make a new call with Retrofit to get those updated cryptocurrency values. That is our retry functionality.
It helps us encapsulate our repository responses according to their state, making it easy for our views to display information accordingly. This is how CharactersFragment observes a LiveData value and updates itself accordingly.CharactersFragment.kt (characters observer)
Retrofit helps us access remote data from our app. You can see how to build a Retrofit object in AppModule.kt. We also need to code interfaces with the HTTP operations that we will perform to communicate with the API.CharacterService.kt
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Whether your app is backing up data to the cloud, authenticating users via “Sign In With Google,” downloading images, or posting content to social media sites, many apps need to be in regular communication with remote servers.
Networking has become such a staple of mobile applications, that there’s a wide range of libraries designed specifically to help you retrieve data from remote servers and share data with the wider internet.
In this article, I’ll show you how to add networking capabilities to your Android app using Retrofit. We’ll take a look at what Retrofit is, and how you can use it to connect to any HTTP-based API service, retrieve data from that API, and then use this data in your app.
Retrofit is a type-safe HTTP client for Android that lets you connect to a web Application Programming Interface (API). You might use Retrofit to connect with the Twitter API so you can display the latest Tweets inside your app, retrieve information about the latest blockbusters with The Movie Database (TMDb) API, or check the forecast via the Weather API.
A Retrofit class: This is where you’ll create a Retrofit instance and define the base URL that your app will use for all of its HTTP requests. In our application, the base URL will be https://jsonplaceholder.typicode.com/
An Interface that defines the HTTP operations: This where you’ll describe each Retrofit request that you want to make, using special Retrofit annotations that contain details about the parameters and the request method.
In most cases, server requests and responses are mapped to a language neutral format such as JSON, rather than provided as Java objects. When you’re using Retrofit, you’ll typically have to deal with serializing and deserializing JSON data:
After we’ve successfully retrieved data from the server, we’ll display it as a list. I’m also adding RecyclerView and CardView as project dependencies.
GET: A method that’s annotated with @GET is responsible for processing a HTTP GET request, where data is retrieved from a server. This is the annotation we’ll be using to retrieve the list of names.
The base URL. It’s not uncommon for project requirements to change, so at some point you may need to switch your project to a different URL. If your base URL is defined in a single location, then you can change it without necessarily touching all of your app’s endpoints. Typically, you’ll define your base URL when you instantiate the Retrofit instance, which is exactly what we’re doing here.
We’re going to implement this functionality in a reusable class, as this allows us to create the Retrofit object once and then reuse it across our entire application.
If you apply multiple converters, then your app will always use the first compatible converter that’s passed to Retrofit, which in the above example is Gson. Assuming that the above code retrieves data that can be processed by either Gson or Moshi, then it will always use the Gson converter.
You can execute Retrofit requests synchronously using call.execute(), or asynchronously using call.enqueue. Synchronous requests get executed on the main thread and run the risk of blocking the main UI thread across all versions of Android. In addition, if you attempt to execute a Retrofit request synchronously on Android 4.0 or higher, then your application will crash with a `NetworkOnMainThreadException` error. So, we’ll be using the enqueue() method to send our request asynchronously.
Retrofit will download and parse the API data on a background thread, and then return the response on the UI thread. We’ll handle this response via onResponse() and onFailure() callback methods, where we’ll define how our application should respond once the request has finished.
In this tutorial, we looked at how you can request information from a remote server, process the response, and display that information in your app using the popular Retrofit HTTP client. We also touched on how to use Retrofit in combination with other libraries, including RxJava, using adapters.
Perhaps the best thing to do with an old flat-screen monitor is a DIY DAKboard. The DAKboard is a LCD wall display that shows the current time, weather forecast, calendar events, stock quotes, fitness data, and news headlines. It"s all displayed on a soothing photo. You could buy an official DAKboard, but the makers themselves have shown how to build your own wall display with a Raspberry Pi. when you can build one for far less money and a little geeky fun, the choice is obvious.
Basically, you will be cutting out the polarizing film of the old LCD monitor. This film will then be put on a simple pair of glasses. Now your screen appears white, but the glasses can "see" the content. It"s one of the best ways to keep prying eyes out of your PC.
If you have a broken old LCD monitor, it can be re-purposed into a usable mirror; but if you have a working old LCD monitor, adding a Raspberry Pi can turn it into a smart magic mirror!
If you"re on a tight budget for a first-time DIY project, consider the $100 smart mirror. It"s not the best version of turning an LCD monitor into a smart mirror, but you"ll get the basic features and not spend a bomb.
In fact, if you have an old monitor and old PC parts, you can repurpose the whole PC. You can turn it into a home security system, a home server or media center, or try other unique creative projects.
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Hence next, you’ll update your app to use the most popular third-party library, Retrofit from Square. As a bonus, you’ll glam up your UI with some images, too.
Retrofit is an Android and Java library that excels at retrieving and uploading structured data, such as JSON and XML. This library makes HTTP requests using OkHttp, another library from Square.
This will add the retrofit dependency for creating network requests and the second dependency adds a converter which automatically integrates GSON to deserialize the JSON and get the model and vice-versa.
Finally, delete the GSON dependency you added earlier: implementation "com.google.code.gson:gson:2.8.6". You no longer need it because the libraries specified with Retrofit handle the parsing and integrates GSON. Then, resync your Gradle files.
Note: Regarding available library versions, you can’t always take what Android Studio tells you at face value. If you want to know the latest version of a library, check the releases page on GitHub. At the time of writing, Android Studio reported Retrofit version 2.7.0 to be the latest, but using this version caused a runtime crash. The GitHub releases page revealed the latest release to be 2.6.3.
This code creates an interface that lets Retrofit connect to the GitHub API. You’ve also added two methods to the interface with @GET annotations that specify the GitHub endpoints to make GET requests.
Has a method to create a Retrofit Call, on which enqueue() makes a network call and passes in a Retrofit callback. A successful response body type is set to RepoResult.
Up to this point, you’ve used the old way of making network calls with Retrofit: callbacks. But the scale and code of the app can grow more complex. This can lead to “callback hell” – when there are multiple API calls and callbacks are wrapped inside callbacks which can be very difficult to maintain.
OkHttp contains a logging interceptor. You can use it to log and debug the network requests and responses that you make with Retrofit. However, Android Studio 3.0 introduced the Android Network Profiler. It replaces the need for the OkHttp logging interceptor. Instead of running or debugging your app, click the Android Profiler icon at the top right corner in Android Studio, as highlighted in the image below.
Explore this Android Networking video course for more details on Android networking and Retrofit. This ViewModel screencast has more details on using ViewModel.
Previously I added in my gradle.build, I"m not sure if I should add GSON since they say Retrofit 1.9 has it but nothing is mentioned about Retrofit 2:
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