The classes and interfaces of other packages can be accessed by prepending their package name. For example, to access the Vector class of the java.util package, you could refer to it as java.util.Vector as in the following example:
java.util.Vector v = new java.util.Vector();
The problem with using the package name is that it adds a lot more text to your code. I recommend that you import the java.util package instead of prepending java.util whenever you reference a class or interface of this package.