import - why autoimport only java.lang package?

Question

I know that the package java.lang is auto-imported by every java program we write, hence all the classes in it are automatically available to us.

My question is why not auto import java.util and other packages too? That sure will save some typing :)

So please explain why is this not done.

Answer 1

A good reason not to autoimport too much is to avoid namespace clashes. If everything in java.util was imported automatically and then you wanted to refer to a different class named 'Map', for example, you would have to refer to it by its fully-qualified name.

In response to other answers in this thread, import does not actually modify the internal representation of your class files. In fact, here is a link to the JVM spec describing the class file structure: see that imports are not stored anywhere.