Java - from first steps to first appsKnowing Java is a must-have programming skill for any programmer. It’s used in a wide array of programming projects?from enterprise apps and mobile apps to big data, scientific, and financial uses. The language regularly ranks #1 in surveys of the most popular language based on number of developers, lines of code written, and real-world usage. It’s also the language of choice in AP Computer Science classes taught in the U.S.