Defining Classes II - Java - page 311

operating system. If you can find out how to set the PATH variable on your operating
system, you will know enough about these topics to understand this section.

Packages and import Statements
A package is Java's way of forming a library of classes. You can make a package from a
group of classes and then use the package of classes in any other class or program you
write without the need to move the classes to the directory (folder) in which you are
working. All you need to do is include an import statement that names the package.
We have already used import statements with some predefined standard Java packages.
For example, the following, which we have used before, makes available the classes
Scanner of the package java.util :

package

import
statement

import java.util.Scanner;

You can make all the classes in the package available by using the following instead:

import java.util.*;

There is no overhead cost for importing the entire package as opposed to just a few
classes.
The import statements should be at the beginning of the file. Only blank lines,
comments, and package statements may precede the list of import statements. We dis-
cuss package statements next.

import Statement
You can use a class from a package in any program or class definition by placing an import
statement that names the package and the class from the package at the start of the file
containing the program (or class definition). The program (or class definition) need not be in
the same directory as the classes in the package.
SYNTAX
import Package_Name . Class_Name ;
EXAMPLE
import java.util.Scanner;

You can import all the classes in a package by using an asterisk in place of the class's name.
SYNTAX
import Package_Name .*;
EXAMPLE
import java.util.*;