- Packages in java are used to organize relevent classes and interfaces
- Every class in java belongs to a package
- If package is not explicitly defined, class will use a default package
- Classes with similar functions can be placed in the same package to make them easy to locate
- Packages are also used to avoid from class naming conflicts
- Packages are also used to group related classes so that they can be easily distributed
- A class or interface can indicate that its Java byte code be placed in a particular package, using a package declaration
- Package declaration appears in a source file, and it must be the first statement
- Provide protection so that the protected members of the classes are accessible to the classes in the same, but not to the external classes
- One can create a package inside another package
- Using class from the other packages, write import statement
import java.lang.Math; //to access math class only
import java.lang.*; //use * to import on demand
For example :
indicates that Math is a class in lang package and that lang is a package in java package. To use Math class one must write the import statement. The following package hirarchy a is wrong because com can’t be a root folder. where as book.com.prenhall is a correct hirarchy.
Example 1 : Student Class in student package
package student; //Package name is student.
//Student class is defined inside the student package.
private int ID;
private String name;