Android is a software stack for mobile devices that includes an operating system, middleware, and key applications. The Android SDK provides the tools and libraries necessary to begin developing applications that run on Android-powered devices. This site provides information about Google projects based on the Android platform, such as external libraries that extend the platform, hosted services and APIs, and more. Everything on this site is provided by Google for the benefit of Android developers. If you are interested in developing applications for Android devices, please visit the Android Developers site at developer.android.com
 The number of people working on mobile apps, and specifically Android, is growing fast. Since modern mobile software-development is a relatively new profession, the community is growing by sucking in experts from related domains, one being web design and development.
It turns out that familiarity with web UI development, particularly using modern HTML5 techniques, can be a great primer for Android UI development. The Android framework and SDK have many analogues to tools and techniques in the Web repertoire of HTML, CSS, and JavaScript. In this blog post, we’ll walk through a few web development features and look for matches in the world of Android UI development.
Device resolutions and physical sizes One of the most important aspects of both Android UI design and web design is support for multiple screen resolutions and physical sizes. Just as your web app needs to work on any physical display and inside any size browser window, your native app needs to run on a variety of form factors, ranging from 2.5” phones to 10” tablets to (possibly) 50” TVs.

CSS3 media queries allow developers to include additional stylesheets to target different viewport and screen configurations. For example, developers can provide additional style rules or override existing styles for mobile devices. Although the markup (layout hierarchy) remains the same, CSS3 has several sophisticated techniques for completely transforming the placement of elements with different stylesheets.

Android has long offered a similar mechanism in resource directory qualifiers. This extends to many different types of resources (layouts, images or ‘drawables’, styles, dimensions, etc). Thus you can customize the view hierarchy as well as styling depending on device form factor, A base set of layouts for handsets can be extended for tablets by placing additional layouts in res/layout-xlarge or res/layout-sw600dp (smallest width 600 density-independent pixels) directories. Note that the latter syntax requires Android 3.2 or later.
Let’s look at some ways in which CSS and Android allow for flexible and adaptive layouts.