None of the memory problems of C++, the speed of C++ most of the time. Thousands of high quality libraries, a JVM that is a marvel of engineering after 20 years, tooling for development, monitoring and introspection of exceptional quality. Many of the internal tools at the largest Cloud developed in Java. Most enterprise level software. NASA extensive use of Java. A team behind the development who has stunning common sense in resisting the latest fads. Support for IEEE 754 that took years. AOT compilation...The infra behind most internet banking sites out there. Use in high speed trading.

What else do you want from the ecosystem?

What would be a modern IDE for Java?

I remember programming Java in Eclipse. And it was powerful for the time, but everytime I read bloated, I automatically think Eclipse since then..

and also FOSS (Apache 2): https://github.com/JetBrains/intellij-community (as well as PyCharm found in the "python" subdirectory)