Set Up Your Environment
•Download Android Studio.
•Download the latest SDK tools and platforms using the SDK Manager
•Java JDK 1.7 and above
•Android application development on either of the following operating systems −
•Microsoft Windows XP or later version.
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•Mac OS X 10.5.8 or later version with Intel chip.
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•Linux including GNU C Library 2.7 or later.
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•Second point is that all the required tools to develop Android applications are freely available and can be downloaded from the Web. Following is the list of software's you will need before you start your Android application programming.
•Java JDK5 or later version
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•Android SDK
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•Java Runtime Environment (JRE) 6
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•Android Studio
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•Eclipse IDE for Java Developers (optional)
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•Android Development Tools (ADT) Eclipse Plug-in (optional)
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•Here last two components are optional and if you are working on Windows machine then these components make your life easy while doing Java based application development. So let us have a look how to proceed to set required environment.
•Set-up Java Development Kit (JDK)
•You can download the latest version of Java JDK from Oracle's Java site: Java SE Downloads. You will find instructions for installing JDK in downloaded files, follow the given instructions to install and configure the setup. Finally set PATH and JAVA_HOME environment variables to refer to the directory that contains java and javac, typically java_install_dir/bin and java_install_dir respectively.
•If you are running Windows and installed the JDK in C:\jdk1.6.0_15, you would have to put the following line in your C:\autoexec.bat file.
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•set PATH=C:\jdk1.7.0_75\bin;%PATH%
•set JAVA_HOME=C:\jdk1.7.0_75
•Alternatively, you could also right-click on My Computer, select Properties, then Advanced, then Environment Variables. Then, you would update the PATH value and press the OK button.
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•On Linux, if the SDK is installed in /usr/local/jdk1.6.0_15 and you use the C shell, you would put the following code into your .cshrc file.
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•setenv PATH /usr/local/jdk1.7.0_75/bin:$PATH
•setenv JAVA_HOME /usr/local/jdk1.7.0_75
•Alternatively, if you use an Integrated Development Environment (IDE) Eclipse, then it will know automatically where you have installed your Java.
Creating An Android Project
•An Android project contains all the files that comprise the source code for your Android app.
•Note: You should already have Android Studio or the Android SDK command-line tools installed. If not, download them before you start this lesson.
•In Android Studio, create a new project:
•If you don't have a project opened, in the Welcome screen, click New Project.
•If you have a project opened, from the File menu, select New Project. The Create New Project screen appears.
•Fill out the fields on the screen, and click Next.
•It is easier to follow these lessons if you use the same values as shown.
•Application Name is the app name that appears to users. For this project, use "My First App."
•Company domain provides a qualifier that will be appended to the package name; Android Studio will remember this qualifier for each new project you create.
•Package name is the fully qualified name for the project (following the same rules as those for naming packages in the Java programming language). Your package name must be unique across all packages installed on the Android system. You can Edit this value independently from the application name or the company domain.
•Project location is the directory on your system that holds the project files.
•Under Select the form factors your app will run on, check the box for Phone and Tablet.
•For Minimum SDK, select API 8: Android 2.2 (Froyo).
•The Minimum Required SDK is the earliest version of Android that your app supports, indicated using the API level. To support as many devices as possible, you should set this to the lowest version available that allows your app to provide its core feature set. If any feature of your app is possible only on newer versions of Android and it's not critical to the app's core feature set, you can enable the feature only when running on the versions that support it.
•Leave all of the other options (TV, Wear, and Glass) unchecked and click Next.
•Under Add an activity to <template>, select Blank Activity and click Next.
•Under Customize the Activity, change the Activity Name to MyActivity. The Layout Name changes to activity_my, and the Title to MyActivity. The Menu Resource Name is menu_my.
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•Click the Finish button to create the project.
•Your Android project is now a basic "Hello World" app that contains some default files
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•………………… End of Project Creation ……………………………..
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Running Your App
•How you run your app depends on two things: whether you have a real device running Android and whether you're using Android Studio. This lesson shows you how to install and run your app on a real device and on the Android emulator, and in both cases with either Android Studio or the command line tools.
•Run on a Real Device
•If you have a device running Android, here's how to install and run your app.
•Run on a Real Device
•If you have a device running Android, here's how to install and run your app.
•Set up your device
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•Plug in your device to your development machine with a USB cable. If you're developing on Windows, you might need to install the appropriate USB driver for your device. For help installing drivers, see the OEM USB Drivers document.
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•Enable USB debugging on your device. On Android 4.0
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•and newer, go to Settings > Developer options.
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•Note: On Android 4.2 and newer, Developer options is hidden by default. To make it available, go to Settings > About phone and tap Build number seven times. Return to the previous screen to find Developer options.
•Run the app from Android Studio
•Select one of your project's files and click Run from the toolbar.
•In the Choose Device window that appears, select the Choose a running device radio button, select your device, and click OK .
•Android Studio installs the app on your connected device and starts it.
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•Run the app from a command line
•Open a command-line and navigate to the root of your project directory. Use Gradle to build your project in debug mode, invoke the assembleDebug build task using the Gradle wrapper script (gradlew assembleRelease).
•This creates your debug .apk file inside the module build/ directory, named app-debug.apk.
•On Windows platforms, type this command:
•> gradlew.bat assembleDebug
•On Mac OS and Linux platforms, type these commands:
•$ chmod +x gradlew
•$ ./gradlew assembleDebug
•After you build the project, the output APK for the app module is located in app/build/outputs/apk/
•Note: The first command (chmod) adds the execution permission to the Gradle wrapper script and is only necessary the first time you build this project from the command line.
•Make sure the Android SDK platform-tools/ directory is included in your PATH environment variable, then execute:
•$ adb install app/build/outputs/apk/app-debug.apk
•On your device, locate MyFirstApp and open it.
•That's how you build and run your Android app on a device!
Android - Architecture
•Android operating system is a stack of software components which is roughly divided into five sections and four main layers as shown below in the architecture diagram.
•Linux kernel:
•At the bottom of the layers is Linux - Linux 3.6 with approximately 115 patches. This provides a level of abstraction between the device hardware and it contains all the essential hardware drivers like camera, keypad, display etc. Also, the kernel handles all the things that Linux is really good at such as networking and a vast array of device drivers, which take the pain out of interfacing to peripheral hardware.
•Libraries:
•On top of Linux kernel there is a set of libraries including open-source Web browser engine WebKit, well known library libc, SQLite database which is a useful repository for storage and sharing of application data, libraries to play and record audio and video, SSL libraries responsible for Internet security etc.
•Android Libraries
•This category encompasses those Java-based libraries that are specific to Android development. Examples of libraries in this category include the application framework libraries in addition to those that facilitate user interface building, graphics drawing and database access. A summary of some key core Android libraries available to the Android developer is as follows −
•android.app − Provides access to the application model and is the cornerstone of all Android applications.
•android.content − Facilitates content access, publishing and messaging between applications and application components.
•android.database − Used to access data published by content providers and includes SQLite database management classes.
•android.opengl − A Java interface to the OpenGL ES 3D graphics rendering API.
•android.os − Provides applications with access to standard operating system services including messages, system services and inter-process communication.
•android.text − Used to render and manipulate text on a device display.
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•android.view − The fundamental building blocks of application user interfaces.
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•android.widget − A rich collection of pre-built user interface components such as buttons, labels, list views, layout managers, radio buttons etc.
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•android.webkit − A set of classes intended to allow web-browsing capabilities to be built into applications.
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•Having covered the Java-based core libraries in the Android runtime, it is now time to turn our attention to the C/C++ based libraries contained in this layer of the Android software stack.
•Android Runtime
•This is the third section of the architecture and available on the second layer from the bottom. This section provides a key component called Dalvik Virtual Machine which is a kind of Java Virtual Machine specially designed and optimized for Android.
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•The Dalvik VM makes use of Linux core features like memory management and multi-threading, which is intrinsic in the Java language. The Dalvik VM enables every Android application to run in its own process, with its own instance of the Dalvik virtual machine.
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•The Android runtime also provides a set of core libraries which enable Android application developers to write Android applications using standard Java programming language.
•Application Framework
•The Application Framework layer provides many higher-level services to applications in the form of Java classes. Application developers are allowed to make use of these services in their applications.
•The Android framework includes the following key services −
•Activity Manager − Controls all aspects of the application lifecycle and activity stack.
•Content Providers − Allows applications to publish and share data with other applications.
•Resource Manager − Provides access to non-code embedded resources such as strings, color settings and user interface layouts.
•Notifications Manager − Allows applications to display alerts and notifications to the user.
•View System − An extensible set of views used to create application user interfaces.
•Applications
•You will find all the Android application at the top layer. You will write your application to be installed on this layer only. Examples of such applications are Contacts Books, Browser, Games etc.