Изучение Android Studio за одну статью! Создание программы с API
ОС Андроид – одна из самых популярных ОС в мире. Мы подготовили большой урок по изучению программы Android Studio и построению полноценного Андроид приложения. За урок мы сделаем программу с API.
Информация про Андроид
На ОС Андроид сегодня работают не только мобильные и планшетные устройства, но также всевозможные часы, телевизоры, компьютеры и даже, как бы это не звучало, холодильники.
Несмотря на огромное множество устройств разработка под многие из них происходит через одну общую программу – Android Studio . Конечно же, у каждой платформы будут свои особенности: размер экрана, характеристики устройства и так далее. Тем не менее, общий процесс создания будет примерно схожим.
Таким образом, изучив Андроид Студио вы сможете в будущем спокойно переходить от одной платформы к другой. Напомним, на сегодняшний день только мобильные устройства на ОС Андроид занимают примерно 85% всего рынка смартфонов.
Языки программирования для Андроид
Разрабатывать под Андроид можно за использованием нескольких разных языков программирования. Зачастую все разрабатывают на основе языка Java, но помимо него можно использовать язык Kotlin, Python, React Native, Flutter и даже на HTML и CSS можно делать проекты.
Ниже видео на тему разработки Андроид проекта на HTML и CSS:
Вы можете использовать разные языки, но наиболее часто используется Джава или его более молодой собрат – Kotlin . В любом случае, если вы только приступаете к Андроид, то ни про какой другой язык помимо Джава вам не стоит думать. Если в будущем нужно будет писать на Котлин, то вам все равно знания разработки Андроид проектов на Джава будут нужны.
Установка всего необходимого
Для разработки под Андроид требуется всего две вещи. Во-первых, вам нужно скачать на компьютер Джава JDK. Это можно сделать через официальный сайт Oracle.
Во-вторых, вам потребуется программа Андроид Студио. Именно она является наиболее популярной программой для разработки приложений под Андроид. Скачать бесплатно эту программу можно также с ее официального сайта . После скачивания Джава и Андроид Студио выполните их установку и далее мы сможем приступить к разработке проекта.
Создание функций
Теперь нам нужно создать весь функционал для приложения.
В приложении мы будем получать данные о погоде. Чтобы это делать сперва зарегистрируйтесь и получите API ключ на сайте OpenWeaterMap .
Теперь остается прописать весь код. Код класса «MainActivity» представлен ниже вместе с комментариями.
Дополнительно скачать полностью весь проект можно по этой ссылке .
Видео на эту тему
Также вы можете просмотреть детальное видео по разработке данного приложения:
Дополнительный курс
На нашем сайте также есть углубленный курс по изучению языка Java . В ходе огромной программы вы изучите не только язык Java, но также научитесь создавать веб сайты, программы под ПК, приложения под Андроид и многое другое. За курс вы изучите массу нового и к концу программы будете уметь работать с языком Java и создавать на нём полноценные проекты.
Більше цікавих новин
Почему Python – это отличный выбор для новичков?
Нужно ли программисту знать английский язык?
Как создать свою криптовалюту?
10 отличных API для ваших проектов
How To Consume Data From an API in Android
APIs allow applications to access a huge range of data. In numerous cases, developers usually connect their software to third party APIs. This move enables them to save a significant amount of time. In Android, tools such as Volley and Retrofit allow you to connect to APIs seamlessly.
Introduction
Android is among the most popular operating systems in the world. Statistics from Google show that more than a billion devices run Android. Therefore, the ability to utilize APIs in our applications helps us satisfy the needs of many users.
One of the major factors that we should consider when using APIs is the number of requests. We should desist from making too many network operations. This is because it can increase battery drain and lead to poor user satisfaction. Also, API owners can bar applications that make too many requests.
This tutorial provides a guideline on how to make an API request based on the user’s action. We will make a simple search app that sends a request to the OMDb movie API and receives data.
Prerequisites
To understand this tutorial, you must have a basic knowledge of Kotlin. Furthermore, you will need Android Studio installed on your computer.
Step 1 — Getting started
Launch Android Studio and create a new project with an empty activity, as shown below.
Give the project any name, and then click on the finish button. Kindly note that the creation of the project usually takes some considerable time. Therefore, you need to be patient.
Step 2 — Installing dependencies
The next step is to install volley and glide dependencies. We will use volley to handle network requests, while glide will help load images in the application.
Add the following lines in the app level build.gradle file.
You then click on the Sync Now button to download and incorporate the above dependencies in the application.
Step 3 — Reviewing the Movie API
We will be sending and receiving data from the OMDb API for this tutorial. Before going further, it is essential to understand how to access the data, the site rules, and the data structure.
Data access
For us to access data, we need to create an account on the OMDb website. This process requires a valid email. You can sign up from here. Kindly note that this tutorial uses the free account option, which has a daily limit of 1,000 requests.
After registration, an API key is sent to your email inbox.
Site rules
One needs to include an API key while making a request to the OMDb API. For instance, the correct link is shown below.
The input variable will allow us to search different movies in the OMDb API. The key is usually placed at the end of the url.
Step 4 — Layout design
The application will have a simple layout like the one shown below.
We will use a LinearLayout to arrange different components on the screen. Note that the layout’s orientation is set to vertical. Here is the code for activity-main.xml .
In the above layout, we have assigned an ID to our components. We will use these unique values in the MainActivity.kt file.
The EditText widget allows us to get the user’s input. When clicked, the search button will initiate a request to the OMDb API. The ImageView and TextViews will display the data returned from the server.
Step 5 — Connecting to the API
This tutorial shows how you to make simple API requests. Therefore, all our logic is in the MainActivity file rather than in a separate component such as a ViewModel . In case you want to learn more about the MVVM architecture in Android, you can read this article.
We need to do the following things in the MainActivity .
- Initiate a requestQueue .
- Make an API request.
- Parse data to UI components.
A RequestQueue helps us manage HTTP requests. You can learn more about the RequestQueue from here.
We initiate a requestQueue by adding the following lines immediately after setting a content view.
The appnetwork variable allows the application to use an HTTP client.
The next step is to add a click listener to our search button. The user will make an API call by clicking this button.
The input variable stores the user’s search term. This value is then passed to the fetchData method as a parameter. Let’s create the fetchData method.
The fetchData function requires a string (user’s input) as a parameter. This string is then joined to the url as =$ . We are using a JsonObjectRequest because our application returns a single Movie object rather than a list. We use an if-else statement to handle different states in the jsonObjectRequest lambda function. If the request is successful, we extract the data and parse it to the components.
The Glide library helps load the image to the ImageView .
An error message is also logged in case the network request fails. This helps in the debugging process.
Finally, the jsonObjectRequest is added to the requestQueue .
Here is the code for the MainActivity.kt .
Kindly note that before testing the application, we need to grant it access to the internet. We should also allow the application to use cleartext traffic. This step is essential, especially if the API source does not have an SSL certificate.
To allow these permissions, open the manifest file. Add the following statement immediately after package="your-package-name"> .
In the same file, scroll to the application section and add android:usesCleartextTraffic="true" .
We can now compile and run the application on our phones.
Conclusion
From the above tutorial, we have learned:
- How to review APIs.
- How to modify urls.
- How to make API requests.
You can, therefore, use this knowledge to develop more complex applications.
Android studio как работать с api
In this post, I will explain how to call an API using Android Studio (Android app) as well as treating its return data. I’ll be focusing mostly on the technical part (like most of the posts I’ll publish here on my blog), however, and only for personal reasons, I will contextualize this scenario and tell you why I followed this solution, but it will be just a brief summary in case you want to know this little “adventure” of mine. If you are only interested in the technical solution please click here.
In one of my school projects¹, my team and I decided to create an Android application for the very first time. The project was basically a meal planner app where the user can create and manipulate recipes as well as organize his/her own weekly meal plan.
I’m printing here below a few screenshots to illustrate a little about the app. When these screenshots were taken the project was still in its initial state:
Weekly Plan Screen 
Recipes Screen
One of the requirements of the project was the use of an API to fetch food items inside USDA’s database (United States Department of Agriculture). I searched in a few technology forums trying to find some practical examples, but I didn’t have much success finding a satisfactory solution which matched with the scenario of this project. So I decided to look for any documentation on the Android website (developer’s section) and I found a relatively new solution (2013) using the Volley library. This is a good solution for low payloads HTTP requests, which are usually used to populate the UI, and this was the perfect solution I was looking for.
In the following chapters, I will explain in details how to make HTTP requests using Volley. So let’s go to the solution already!
If you’d like to check the project’s source code, please follow the GitHub link²
(¹) Langara College: Web and Mobile App Development — WMDD4980 Project 2
(²) The available source code of the project is only a demo of the app, for obvious reasons I won’t share the whole code of the app.
Contents
1. Know The API You Are Going to Use
Firstly, it is necessary to know the API you will use. In this case, it is the USDA’s database, you can find its documentation following this link.
Usually, an API requires an access key, so you will probably need to sign up on their website and justify the use of the API, but it should be something very simple.
It’s very important to know about the API’s inputs and outputs as well, so I enforce that checking its documentation is crucial for the correct use and avoiding possible crashes.
2. Hands On (coding)
2.1. Adding Volley & Internet Permission
To use Volley’s tools, we need to add its library first. The easiest way to do that is by adding the dependency inside the file build.gradle .
Next, it’s necessary to add internet permission to your app, so add the following code between the tag manifest , inside the file AndroidManifest.xml
2.2. Creating the Queue Object
Now we need to create the object which will manage the communication between the app and the API, so we create the RequestQueue object.
For our solution, we’ll make use of the Volley.newRequestQueue .
2.3. Creating The String Request
The StringRequest object represents the data to be sent (method and URL), as well as its treatment (logic) in case of success and error of the invoked API.
2.3.1. Setting The Success and Error Returns
In the case of this project, I decided to create a separate method that returns a StringRequest object, so that way I wasn’t “polluting” the event method a lot.
2.4. Calling The API
Now that we defined the rules and procedures to the API’s return, we just need to make the call of itself. The operation is as simple as adding the StringRequest to the queue .
3. Conclusion
I found the usage of the Volley library very simple and easy to use. For a simple query like the example above, this solution performed at a good speed and it seems stable. If you need to make a simple request to retrieve light amounts of data, then this is probably a good way to call for the API you want.
You can also find some good explanations about the Volley library on YouTube here in this link.
How to implement REST API in Android using Retrofit in Kotlin (Part-1)
While developing an Android application we have to communicate to servers and databases for data. Fetching, creating and manipulating of data from android can be done by using REST APIs. In this article I am going to show you how to implement these APIs in an Android application using Retrofit library.
This series is divided into 3 parts: Part 1 covers the implementation of GET request, Part 2 covers POST request and the Part 3, the final one covers the DELETE request.
To switch to next parts scroll down to bottom of this article.
For this series, I am using https://jsonplaceholder.typicode.com/ for sample REST APIs.
First of all create a project in Android Studio.
After creating the project, add some libraries to app/build.gradle file.
After that, add this also
Now I will arrange my file structure according to MVVM(Model view viewmodel architecture)
Now we are set to jump right into code!
First let’s create our Model class, i.e; PostModel
Now let’s setup the network classes which will help us to handle APIs in which we will create our Retrofit client.
Next we will make an interface called ApiInterface
Now lets see the function to fetch all the posts.
We will call this method from our viewmodel class.
Next we are going to make layout for main activity. I have added a recyclerview in it.
Now create a layout for a particular item of a post.
In our Main Activity, we will initialize our our Recyclerview Adpater and display the fetched result.
Now lets take a look at our adapter till now.
Now we can see our fetched data in our device.
Hence, we have implemented our first REST API via GET request in Android and displayed it using Retrofit.
Next we will create a post using retrofit via POST request in the next story. Click this link to reach there (PART 2).
How to build REST API in Android Studio using Kotlin
We can able to build a robust android app and I know we have spent a lot on App architecture, UI, UX, animation etc.
One thing we are lagging is how to build REST API.
Wait a sec. I can build REST api with Django-Python or with Google App Engine using java or GO.
Here the tutorial to build REST API using Kotlin in android studio itself.
Create an android project. (I know that you know this procedure so skipping it)
Create a java library module by right clicking on the project name -> New -> Module -> Java library
Name it backend or whatever name you want.
now rename the java folder in your backend module to kotlin.
Open Build.gradle under your backend project and paste it.
Now create Main.kt file (Rememeber file name should be same as in main class name <class_name>Kt)
Paste the following code in the kotlin file
Now run the Main.kt file in the android studio.
Open Browser and hit localhost:8080
Hooray you did it.
To learn more visit http://ktor.io
You can integrate your favourite framework, database etc and build a backend. Host it in AWS, Google Compute Engine etc.