Library

Question

how to develop a cutom library in java ? what are the feasibilities let to know

Answer 1

You can use maven or gradle for easy going and to compile your project to a jar file.
This *.jar file will contain the code of your library.
As for the file structure you can use an IDE like IntelliJ, Eclipse, etc. just make sure to check the maven or gradle development section so that you can compile it to jar easily. You can search how to perform these on web.
As for the feasibilities it's same as code compiled to apps or you can take reference of Java itself which contains libraries that reduces production time by reducing lines of code.

Answer 2

if it is for your need, create a package in a subdir and import it