Is it okay to learn Java without learning data structure?

It depends on how high you want to go.

Ordinary programmers don't need to understand, as long as they realize their functions within the framework, they don't need to learn.

But if you want to go further on this road, it is necessary to study.

Note: If you are just starting to learn for a year or two, you can conquer java first, and don't be overwhelmed by a lot of things.