What is the proper way of using JDK on WSL2 on Windows 10?

I have installed Ubuntu 20.4 LTS on WSL. My windows 10 already have the JDK installed. Do I need to install JDK on ubuntu on WSL or can I use the Windows 10 JDK in the Ubuntu? How you do Java programming on WSL? Which is the proper way?

I was just wondering if I need to install all the development tools and binaries again on Linux won't it take a lot of space & hog a lot of CPU/Ram resources?

There is not a "proper" (as in supported or recommended by JDK providers) way to install or use Java on WSL. I could not find any official recommendations.

However, it is possible to either install and use Oracle JDK for Windows installation from WSL, or install OpenJDK Java into your WSL world from the Ubuntu package manager.

I was just wondering if I need to install all the development tools and binaries again on Linux won't it take a lot of space & hog a lot of CPU/Ram resources ?

See above. But note that you are only going to "hog CPU/RAM" if you are running both kinds of JVM at the same time.

References:

• Installing Oracle JDK on Windows subsystem for Linux
• Java JDK 11 install script for Windows Subsystem for Linux (WSL)
• Windows Subsystem for Linux Java Setup ... using the Ubuntu package system.

^{(There are many more articles on this topic if the above don't address your concerns.)}