What a compiled method in java means

Question

Please, I often find java methods empty with comment compiled code

Here is an example

public E get(int index) { /* compiled code */ }

I can not find the point! thanks for your clarification

Answer 1

This often happens when you use an external library.

This means that your IDE does not contain the source code for this library. Therefore, he knows the name of the method and signature, but not its code