3 billion devices run Java

At least, that’s what the JRE installer window on Microsoft Windows claims, and that figure has remained unchanged for decades. However, there is a hidden message in this: Java was then and remains now one of the most portable platforms for the “write once, run anywhere” approach. Its mobile version, J2ME, was a way to bring the vast diversity of mobile operating systems in the early 2000s to some common ground. Even smartphones that had native apps were required to support J2ME. Everything changed with the arrival of the iPhone on the market, but until then, our guarantee for running proper web browsers, messengers, and e-books was J2ME.