Cross platform used to mean, windows, mac, and linux. These days it is web, ios, android, windows, mac, and linux. In that order. And that's before you consider

Cross platform used to mean, windows, mac, and linux. These days it is web, ios, android, windows, mac, and linux. In that order. And that's before you consider TVs, cars, and other equipment where apps are also relevant. These days web is the new cross platform technology. It works everywhere. And mobile is where people focus for native apps. Windows is an afterthought at best. Mac even more. And Linux oddly is now a main source of open source applications that also work on windows and mac. But it's not a big market. Unless you consider Android a linux distribution. In that case it's absolutely huge. And Java/Kotlin are the languages of choice on that platform. But they are compiled to native ahead of time so don't require a JVM. Otherwise, Applet support for browsers died a long time ago so that blocked Java from being useful on the web. The JVM as distributed by Oracle (and other openjdk packagers) only really covers the traditional three desktop platforms. And it's not really native there and kind of heavy weight. That limits the appeal. Java is not really that cross platform anymore. Sun failed to anticipate and survive the move to smartphones. Up until then J2ME was a thing. These days almost no phone comes with Java support. That's the real reason Java usage on the desktop declined. It did not cover new platforms from about 2007 onwards. Despite this there's a new JVM framework on the block: compose desktop. It uses skia (like flutter) and there's a mobile variant supported by Google called jetpack compose. And a web variant called compose web. IOS support is missing. But that looks like it might be addressed at some point.