Java did replace C++ in many domains, but not all simply because the JVM requires more overhead than C++.

The trade-off was more overhead, but faster development and fewer errors due to not needing to manage memory or other low-level details.

Java is easier to write than C++ and is more portable than C++, but needs more time to get fast and more memory to work with.

By way of comparison, Rust offers all of the speed of C++ and similar low overhead with practically none of the footguns that C++ is known for.