Many smartphones and mobile computing devices run the Android platform. This allows users to download and install Android apps from the official Market. The Market offers apps for many different purposes, including business, productivity, communication, entertainment and reference. To create Android applications of your own, you need a number of software tools. You can acquire the necessary tools for free, but you must purchase an Android Developer Account to release your apps through the Market.
Development Resources
To develop Android apps, you need a few development resources on your computer. You can download the Eclipse Integrated Development Environment from the Eclipse Foundation website. Android apps use Java, so you also need the current Java Development Kit, which is available on the Oracle website. The official Android development tools include the Android Software Development Kit and the Android Developer Tools plug-in for Eclipse, both of which you can download from the Android website.
Android Projects
To create Android applications, you can start a new Android project in Eclipse. Before you start creating Android applications, you may need to familiarize yourself with the application framework, an overview of which you can read on the Android Developers Guide website. Android apps use Activities to model individual screens within user interfaces, as well as Java class declarations to implement any logical processes required. Using the available Android code components, you can carry out the processing necessary for your project. In addition to Activities, Android apps use Services for background operations, Content Providers for application data management and Broadcast Receivers for responding to system events.
User Interfaces
User interface design within Android involves layouts. The XML files within an Android project define the layouts for each part of an application. A layout determines how the visible elements within each Activity are displayed, as well as including interactive components such as buttons, text-fields and drop-down lists. You can also create and use digital images within your Android apps by including them within your project folders and linking to them in your layout files.
Testing
Within Eclipse, you can run and test your Android apps on virtual devices. The Android Virtual Device Manager allows you to define a set of one or more virtual devices to run within the emulator. This means you can see how your apps will perform on devices with various configurations in hardware and software. Within Eclipse, you can also export development versions of apps you're working on, so that you can copy these onto any actual Android devices you have access to in order to test them.
Release
To release apps through the official Android Market, you need to sign up for a Developer Account. Once you have an account, you can sign into your Developer Console, through which you can upload new apps, as well as upgrade existing apps. To do this successfully, sign and version your apps correctly. Signing involves using an encryption key within Eclipse, which must be the same for upgraded versions of an app. To version an Android app, you need to include incrementing version numbers within your application's Manifest XML file. The version number has to increase with each upgrade of an application.
References
Resources
- Android Developers Guide: Declaring Layout
- Android Developers Guide: The AndroidManifest.xml File
- Android Developers Guide: Publishing on Android Market
- Android Developers Guide: Managing Virtual Devices
- Android Developers Guide: Versioning Your Applications
- Android Developers Guide: Signing Your Applications
