> The parenthesized comment is funnier to me because I had to download a specific bazel version to build.
If you use bazelisk to provide your `bazel` command, it'll download the appropriate Bazel version for the repo you're trying to build.
Bazel's single-binary distribution brings its own JVM, it has less dependencies than gn.
Most people use Bazelisk: https://github.com/bazelbuild/bazelisk
> Every time I build tensorflow I have to build bazel first, or get the bazel version for the tf version.
This is fixed now: https://github.com/tensorflow/tensorflow/commit/991aec351b57...
If you use Bazelisk (https://github.com/bazelbuild/bazelisk), you'll automatically get the matching Bazel version for TensorFlow in the future (and all other projects that have adopted the .bazelversion file).
You don't need to install Java. It's bundled. In fact I'd recommend that you don't even install Bazel itself. Instead, install this: https://github.com/bazelbuild/bazelisk. This will install either the latest Bazel for you automatically, or you can pin a version of Bazel you want in each repository, to limit and control build system churn.