IndianTechnoEra: Introduction to Android development

Agenda:

- Mobility

- Approaches

- Android architecture and components

- Android Studio and development environment setup

- Android SDK and tools

This section covers the basics of Android development, including the architecture and components of Android, setting up Android Studio and the development environment, and understanding the Android SDK and tools.

Introduction:

Today's world has become increasingly mobile with smartphones and tablets bringing information and applications to people on the go. 

Android is a popular mobile platform for developers due to its open source nature, wide device support and rich feature set. 

This chapter will discuss Android fundamentals to help you get started developing Android applications.    

Mobility :

Mobility refers to accessing information and using devices from anywhere. With mobile devices becoming an extension of ourselves, users expect:   

• Access to emails, calendars, contacts and other data from any device, anywhere   

• To install and use applications specific to their needs and interests  

• An experience that is tailored to the constraints of small screens and limited resources of mobile devices

To meet these demands, developers need to build mobile versions of applications optimized for the unique characteristics of smartphones and tablets.

Mobility is not just about glittering mobiles or gleaming tabs, but about transforming user experience from the confines of a desk to the convenience of anytime anywhere.

The spontaneity, ubiquity, and indispensability of mobility are indeed defining it as the seventh sense. Mobility panorama can be broadly classified into the following points;

• Logical landscape and 
• Physical ecosystem

Logical landscape:

The logical and escape describe the rationale behind the mobility of different stakeholders where as the physical ecosystem portrays the infrastructure that enables mobility.

Landscape defines two predominant logical components of mobility;

• a. Consumer mobility 
• b. Enterprise mobility

Consumer mobilities are focused on the end user and typically comprises mobility solution and such as social networking, games, shopping, building app utilities. 

Enterprise Mobility is focused towards various stakeholders of an organization such as vendors, partners, suppliers, and workforce. And their end users. 

Physical ecosystem:

The physical ecosystem of mobility encompasses 3 key distinct physical components. Mobile components, enterprise components and middleware and protocols that glue the first 2 components.

Mobile Platforms:

Operating systems that power and manage the computing resources have come off ages. Write from mainframe operating systems to desktop and server operating systems. And now mobile operating systems, more popularly known as mobile platform.

    Technically, a mobile platform is not just an operating system, but a software has tag that typically comprises an operating system, libraries, and application development framework. 

The operating system contributes to the core features of the platform, such as memory management, process management and various device drivers. 

The Libraries Furnish the much needed core functionality of the platform, such as media libraries that provides codecs,  Libraries for native data storage. Rendering screens and drawing surfaces and libraries for graphics. 

The Application Development Framework is the set of Application Programming interface (APIs). That in turn interacts with the underlying libraries and are exposed to the developers for app development.

Popular mobile platforms currently available:

• Android - The most widely used, with an open source model and runs on a huge range of devices.

• iOS - Developed by Apple and runs exclusively on iPhone, iPad and iPod Touch.

• Windows Phone - Microsoft's mobile OS, designed around the Metro User Interface. 

• BlackBerry OS - BlackBerry's proprietary operating system built for business use cases.

App development aspects:

App development key aspects: The development of mobile apps is purely driven by the following 3 key aspects.

Business use case: The app is going to mobilize, business-to-consumer, Business to employer, business to business

User Profile: Who is going to use the app? The user may be a field agent, customer, partner, Executive, or member of. Senior management.

Mobile device: The mobile device that plays the app like the device type, device connectivity, and the operating environment plays key roles in this case.

App Development Approach:

There are several app development approaches available to developers, each with its own advantages and disadvantages. Some of the most common app development approaches include:

Native App Development Approach: 

Native app development involves building an app specifically for a particular platform, such as Android or iOS. 

Native apps are built using the official development tools and programming languages for that platform, such as Java or Kotlin for Android and Objective-C or Swift for iOS. 

Native apps offer the best performance and user experience, as they can take full advantage of the device's hardware and software features. 

However, development time and costs can be higher, as separate versions of the app need to be developed for each platform.

Web App Development Approach:

It involves building apps using web technologies such as HTML, CSS, and JavaScript, which are then accessed through a web browser on a mobile device. 

Web apps are platform-independent, meaning they can run on any device with a web browser. 

However, they offer limited access to the device's hardware and software features, resulting in lower performance and a less engaging user experience.

Hybrid App Development Approach:

It involves building apps using a combination of web technologies and native APIs. 

This approach allows developers to build apps that have a native look and feel, while still using web technologies for the app's core functionality. 

Hybrid apps are cross-platform, meaning they can run on multiple platforms with a single codebase. Hybrid apps offer better performance and user experience compared to web apps and are more cost-effective compared to native apps. 

However, hybrid apps may have limitations in terms of performance and functionality compared to native apps.

Cross-Platform App Development:

Cross-platform app development involves building an app using a single codebase that can be deployed on multiple platforms, such as Android, iOS, and Windows. 

Cross-platform development frameworks such as React Native, Xamarin, and Flutter allow developers to build apps that look and feel like native apps while sharing much of the same code. 

Cross-platform development can save development-time and costs, while still providing good performance and user experience. 

However, cross-platform apps may not be able to take full advantage of the device's hardware and software features and may require additional development effort to ensure compatibility across different platforms.

Low-Code App Development: 

Low-code app development platforms allow developers to create apps using visual development tools and drag-and-drop interfaces, rather than writing code from scratch. 

Low-code app development platforms can significantly reduce development time and costs, making app development more accessible to businesses and individuals with limited resources. 

However, low-code app development platforms may have limitations in terms of customization and functionality, and may not be suitable for complex apps.

No-Code App Development:

No-code app development platforms allow non-technical users to create apps without writing any code. 

No-code app development platforms provide pre-built templates, drag-and-drop interfaces, and visual development tools that allow users to create simple apps without technical expertise. 

No-code app development platforms can be ideal for small businesses or individuals with limited resources, but may not be suitable for complex apps or apps that require advanced functionality.

Hybrid approach philosophies:

Philosophies to build apps using a hybrid approach.

Web-centric philosophy:

This approach emphasizes the use of web technologies to build apps optimized for the mobile web. 

It prioritizes development efficiency and cross-platform compatibility, but may not be able to take full advantage of the device's hardware and software features.

Native-centric philosophy :

This approach emphasizes the use of native app development tools and programming languages to build apps that have a native look and feel. 

It prioritizes delivering the best possible performance and user experience, but may require additional development effort and expertise.

Hybrid-centric philosophy:

This approach emphasizes the use of a combination of web technologies and native APIs to build apps that have the best of both worlds. 

It prioritizes development efficiency and cross-platform compatibility while still delivering good performance and user experience.

Android Overview:

Key aspects of Android:  

• Android is an open-source mobile native platform allowing anyone to modify the source code to customize the OS.

• It is governed by Open Handset Alliance (OHA) and led by Google.

• Since its debut in 2007. It has grown phenomenally and established itself as a comprehensive software platform for smart devices with varying form factors and features.

• The Android platform follows a layered architecture approach.

• The platform is based on a Linux kernel and has native libraries, an Android runtime application framework, and applications as layers in the software stack.

• Supports a huge variety of devices with different hardware specs through adaptive layouts.   

• Android is a mobile operating system developed by Google. It is based on the Linux kernel and is designed primarily for touchscreen mobile devices such as smartphones and tablets. 

• Android applications are developed using the Android SDK, which is a set of tools and libraries that enable developers to create applications for Android devices.

• Android is written in Java and Kotlin programming languages. 

• Widgets - Components that display information and act as app shortcuts on the Home screen.   

• Intents - Allows communication between app components like Activities and Services.   

• Activities - Represent a single screen with a user interface. From the building blocks of an app.

• XML - The Android User Interface is defined using XML layout files.

Features of Android:

• Open source 

• Wide device support    

• Rich UI elements - Buttons, TextViews, ImageViews, Lists, etc.

• Built-in location features using GPS, network providers   

• Capable of playing audio and video natively

• Support for hardware features like camera, Bluetooth, sensors

• Push notifications using Google Cloud Messaging (GCM)

• Easy integration with Google services - Maps, Drive, Analytics, etc.

Architecture and Components:

Android Architecture and Components:

The Android operating system consists of several layers, including the application layer, the framework layer, and the kernel layer. 

Applications layer:

The applications layer is the topmost layer that contains all the apps installed on the device, including those that come bundled with it. 

This layer uses all the layers below it for proper functioning of these mobile app 

Presentation Layer: Handles UI components and user interactions. Domain Layer: Represents core business logic and rules.

Data Layer: Manages data access and storage operations. External Services Layer: Deals with external services and libraries.

Application Framework:

The application framework is a collection of APIs. That are very crucial for an Android developer as the framework forms the basis of the development of Android apps. 

This framework is made available to developers as Android Software Development Kit (SDK). 

That comes along with the Android developers Tool (ADT). This layer is written in Java. 

It has following key components:

• Window manager: It manages windows and drawing surfaces, and is an obstruction of the surface manager library.

• Content providers: It provide the mechanism to exchange data among apps.

• Package manager: It keeps a tab on apps installed on the device.

• Telephony manager: IT enables app to leverage phone capabilities of the device.

• Resource manager: It is used to store the resources of an app such as bitmaps, strings, layouts, and other artwork. 

• View system: It contains the User Interface (UI) building blocks such as buttons, check boxes, and layouts, and also performs the event management of UI elements. 

• Location manager: Deals with location awareness capabilities, 

• Notification manager: Deals with notifications on mobile devices.

Libraries:

The native libraries lie at the heart of the android plaform, and are written in C C++.

Android Jetpack: Provides a set of libraries and tools for building Android apps. Networking Libraries: Facilitate network communication and API integration. Dependency Injection Libraries: Assist in managing dependencies between components. Testing Libraries: Provide tools for testing Android applications.

It has following key components:

• Surface manager library: Render the windows and drawing surfaces of various apps on the screen.

• Media framework library: Provides media codecs for audio and video.

• SQLite librariy: Provides support of native data storage.

• OpenGL (Open Graphics Library): It is the graphics library for 3D rendering.

• SGL (Scalable Graphics Library): It is the graphics library for 2D rendering.

• FreeType library: Render the fonts.

• WebKit library: A browser engine for Android browser.

Android Runtime:

The android runtime is designed to run apps in a constrained enviroment that has limited muscle power in terms of battery, processign, and memory. 

Android Runtime (ART): Executes and manages the execution of Android applications. Java Development Kit (JDK): Provides the runtime environment for executing Java-based apps. Kotlin Runtime: Includes the necessary components for executing Kotlin code.

It has two key components 

• Dalvik Virtual Machine (DVM): Runs executalbe files of an app

• Core libraries: Written in Java and comprise core java libraries such as Utility, collections, and IO (Input/ Output)

Linux kernel:

It procides the core operating system infrastructure such as memory management, process management, security model, networking, and various device drivers. 

Linux Kernel Forms the foundation of the Android operating system, providing essential services for hardware abstraction and process management.

Device Drivers: Enable communication between the operating system and hardware devices.

Hardware Abstraction Layer (HAL): Provides a standardized interface for interacting with hardware-specific drivers.

Environment Setup:

Android Studio and Development Environment Setup:

Android Studio is the official Integrated Development Environment (IDE) for Android app development. 

It is based on the IntelliJ IDEA platform and provides a comprehensive set of tools for developing Android applications. 

To set up Android Studio on your computer, follow these steps:

1. Download and install Android Studio from the official website.

2. Install the Java Development Kit (JDK) on your computer if it is not already installed. Android Studio requires JDK version 8 or higher.

3. Open Android Studio and follow the on-screen instructions to complete the setup process.

4. Once Android Studio is set up, you can create a new Android project by selecting "New Project" from the welcome screen.

Android SDK and Tools:

The Android SDK is a collection of tools and libraries that developers use to build and test Android applications. 

The SDK includes tools for compiling and debugging code, as well as libraries for accessing device features such as the camera and sensors.

Tools in Android SDK:

Some of the important tools included in the Android SDK are:

1. Android Debug Bridge (ADB): A command-line tool that allows developers to communicate with a connected Android device or emulator.

2. Android Virtual Device (AVD) Manager: A tool for creating and managing virtual Android devices for testing and development purposes.

3. Android Asset Packaging Tool (AAPT): A tool for packaging application resources into the APK format used by Android devices.

Example:

Example Code and Implementation:

Let's take a simple example to demonstrate how to create an Android application using Java programming language.

1. Open Android Studio and create a new project.

2. Give your project a name and select the minimum SDK version you want to support.

3. In the project structure, you will see several folders, including the app folder. Open the app folder and then open the java folder.

4. Right-click onthe java folder and select "New" -> "Java Class".

5. In the "Create New Class" dialog box, give your class a name and click "OK".

6. In the code editor, you will see the skeleton code for your class. Add the following code to create a simple user interface:

```java

import android.app.Activity;

import android.os.Bundle;

import android.widget.TextView;

public class MainActivity extends Activity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        TextView textView = new TextView(this);

        textView.setText("Hello, Android!");

        setContentView(textView);

    }

}

```

7. Save the file and run the application on an Android device or emulator.

This code creates a simple user interface that displays the text "Hello, Android!" on the screen.

Types of Android Apps

• Phone: Contacts, Messages, Dialer, etc.

• Tablet: YouTube, Gmail, Gallery, etc.

• Widgets: Clock, Calculator, Music player

• Games: Casual, Arcade, Puzzle

• Productivity: Calendar, Notes, Tasks

• Social: Facebook, Instagram, WhatsApp

• News: Flipboard, Feedly, NY Times  

• Music / Video players

• Shopping: Amazon, Flipkart, eBay

• Finance: Google Wallet, PayPal

• Location based: Foursquare, Uber, Ola  

Activities, Intents, XML Layouts...

Snippet:

Snippet: Showing a Toast

```java

Toast.makeText(this, "Hello!", Toast.LENGTH_SHORT).show();

```

Snippet: Playing audio

```java

MediaPlayer mediaPlayer = MediaPlayer.create(this, R.raw.soundfile);  

mediaPlayer.start();

```

Hope this expanded chapter with more content types helps! Let me know if you have any other questions.

Activities & Intents in Code:

An Activity class:

```java

public class MainActivity extends Activity {

   protected void onCreate(Bundle savedInstanceState) {

      super.onCreate(savedInstanceState);  

      setContentView(R.layout.activity_main);

   }

}

``` 

Corresponding XML Layout:

```xml

<LinearLayout xmlns:android="..." ...>

   <TextView  

      android:layout_width="wrap_content" 

      android:layout_height="wrap_content"

      android:text="@string/hello_world"/>

</LinearLayout>  

```

Important Content:

In addition to the topics covered above, it is also important to understand the following concepts related to Android app development:

1. User interface design: Android provides a rich set of user interface components such as buttons, text fields, and images. It is important to understand how to design a user interface that is both visually appealing and easy to use.

2. Data storage: Android provides several options for storing data on the device, including shared preferences, SQLite databases, and file storage. It is important to understand how to use these storage options to store and retrieve data in your application.

3. Networking: Android provides APIs for accessing the internet and communicating withweb services. It is important to understand how to use these APIs to build network-enabled applications.

4. Security: Android provides several security features such as permissions, encryption, and secure networking protocols. It is important to understand how to use these features to keep your application and user data secure.

5. Performance: Android devices come in a variety of hardware configurations, and it is important to optimize your application's performance to run smoothly on different devices. This includes optimizing memory usage, minimizing network calls, and using threading and background services appropriately.

In conclusion, Introduction to Java Programming for Android app development is an exciting and important topic for aspiring Android developers. 

By understanding the Android architecture and components, setting up the development environment, and mastering the Android SDK and tools, you can start building your own Android applications. 

Additionally, understanding the extra important concepts such as user interface design, data storage, networking, security, and performance will help you create high-quality and successful applications.