I am wondering if we can use index to access List
For example:
List list;
list[5] //blah....
No, you're restricted to List.get (i).
The brackets [] are defined on syntax level, not as method-name, so you can't override them. They are used just for arrays exclusively.
If you like to migrate to Scala, a more modern language for the JVM, you'll find an unified access to arrays and lists, but both with () parentheses.