<aside> 💡 Java has an organizational unit called package.

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Can use import to use packages directly: import java.math.BigDecimal

• To import all classes in the java.math package:

  import java.math.* → * denotes all.

<aside> 💡 Note that * is not recursive. → Cannot write : import java.* → Will NOT import all packages in java.

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Creating and Naming Packages

• Aim: To build or create our own packages.

The naming convention for packages in java is similar to Internet Domain name, but in reverse:

• Internet Domain: onlinedegree.iitm.ac.in
• Package Name: in.ac.iitm.onlinedegree

Add a package header to include a class in a packge:

package in.ac.iitm.onlinedegree;

public class Employee { ... }
// This class is now available in the above defined package.

<aside> 💡 By default, all classes in a directory belong to the same anonymous package.

</aside>

More About Visibility

• Recall the modifiers public and private

<aside> 💡 If we don’t specify modifiers, the default visibility is public within the package. (Applies to both methods and variables)

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We can also restrict visibility with respect to the class inheritance hierarchy → i.e, visibile to subclasses only.

• Use protected modifier → Means that it is visible within the subtree → All subclasses.