This week's book giveaway is in the OCAJP forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide 1Z0-808 and have Jeanne Boyarsky & Scott Selikoff on-line! See this thread for details.
An import statement enables you to refer to a class by the shortened form of its name("ArrayList") versus having to refer to it via its fully qualified name ("java.util.ArrayList"). That is, the following two classes are equivalent:
Also note that the Java Virtual Machine's class loader is a "just in time" loader, meaning that it only loads the bytecode for a class into its memory when you first need it at run time -- i.e., the first time you instantiate an object of a particular type. Please see comments below.