Namespace management refers to the concept of preventing naming collisions. There are a lot of programmers out there writing a lot of Java files, some of which are bound to have the same name.

For example, say you're writing a program and you want to use two different Graph classes, written by two different people. The packages they're in can be used to distinguish them.

Previously in this class, when you wanted to use a class someone else wrote (say, the ArrayList), you imported it with the statement

Then you could instantiate a new ArrayList like so:

It turns out that the import statement is doing nothing more than namespace management. It allows the programmer to refer to a class by its name rather than by its full name including the package it is within. The compiler later substitutes the shorthand for the full class names.

In the example above, all the import statement is doing is telling Java that we want to use the ArrayList class that is in the package java.util, and not some other ArrayList class that someone else wrote.

Java actually allows you to forego the import statement if you fully name the package yourself. For example, if you don't import ArrayList, you can still use it, but you have to refer to it with its complete package name. Here's something to try out: initialize a new ArrayList object without importing it first.

This looks like a lot of effort to type out every time. The import statement allows us to state upfront that every time we refer to the class ArrayList, we mean to use the one inside java.util. If you want to use two different ArrayList classes in your code, each from different packages, then the import statement won't help you. You just need to refer to each by their complete package name.