Packages:
A package is a grouping of related types providing access protection and name space management. Note that types refers to classes, interfaces, enumerations, and annotation types.
A package is a collection of related classes.
It helps Organize your classes into a folder structure and make it easy to locate and use them.
More importantly, It helps improve re-usability.
Creating a class inside a package
Create a directory structure as shown in image
Main.java
public class Main
{
// your code
}Vehicle.java
If your code belongs to package then your programs first line should be
package <packagename>
package sam;
public class Vehicle
{
public int a = 10
//your code
}Car.java
package sam.test;
public class Car
{
// your code
}Accessing a class located in different package
There are two ways to access class located in another package
- Use import statement to access the class
Star(*) imports all classes located in the package specified.
import sam.*;
import sam.test.*;
But the best practice is to import only the specific class
import sam.Vehicle;
import sam.test.Car;
To access vehicle and car class in Main
import sam.Vehicle;
import sam.test.Car;
class Main
{
public static void main(String[] args)
{
Vehicle v1 = new Vehicle();
System.out.println(v1.i);
}
}Compile all classes and run Main.java to check the output
- Instead of importing the class you can import it while creating the object
sam.test.Vehicle v1=new sam.test.Vehicle();
class Main
{
public static void main(String[] args)
{
sam.test.Vehicle v1 = new sam.test.Vehicle();
System.out.println(v1.i);
}
}This type of import will be used to avoid import conflicts when we have same class name in different package
