Java Reference
In-Depth Information
$ export CLASSPATH="/home/joeuser"
$
Now Java knows where to look to find classes of the
com.myco.financial and com.myco.util packages.
The import Statement
3.3.2
Once we have put our classes into packages, we have to use that package's name
when we refer to those classes—unless we use the import statement.
Continuing our example, if we want to declare a reference to an Account
object, but Account is now part of com.myco.financial , then we could refer
to it with its full name, as in:
com.myco.financial.Account =
new com.myco.financial.Account(user, number);
which admittedly is a lot more cumbersome than just:
Account = new Account(user, number);
To avoid the unnecessarily long names, Java has import statements. They
are put at the beginning of the class file, outside the class definition, just after
any package statement. In an import statement, you can name a class with
its full name, to avoid having to use the full name all the time. So our example
becomes:
import com.myco.financial.Account;
// ...
Account = new Account(user, number);
If you have several classes from that package that you want to reference,
you can name them all with a “ * ”, and you can have multiple different import
statements, as in:
import java.util.*;
import com.myco.financial.*;
// ...
Account = new Account(user, number);
Here are a few things to remember about import statements. First, they
don't bring in any new code into the class. While their syntax and placement
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