Day 21. Writing Android Apps with Java

Once viewed primarily as a language for programs on a web page, Java has established itself as a powerful general-purpose programming language that can be run on desktop computers, Internet servers, tablets, appliances, and many other platforms. One platform in particular has in the past decade become an exciting and commercially lucrative area for new Java development: Android.

The Android operating system began on cell phones and quickly became the brains for a large number of other devices. All programs on Android are written in Java.

These programs, which are called apps, are developed on a free open source mobile OS that’s enormously popular. Android does not require costly development tools, licensing ...

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