Java Package and Import Example

What is package

✓ A package in Java is a mechanism used to group related classes, interfaces and sub-packages together.

Key Benefits

• Prevents Naming Conflicts: Two classes can have the same name if they live in different packages.

• Easier Maintainability.

• Better Access Control.

How to Create a Package

package chennai.south;
public class KoyambeduMarket
{
public static void main(String[] args)
{

}
public void buyVeg(){
System.out.println("Buy vegetables at low cost");
}
}

The class KoyambeduMarket created by package chennai and exist in sub package south.

├── KoyambeduMarket.java
└── chennai
└── south
└── KoyambeduMarket.class

package chennai.north;
public class KasimeduMarket
{
public static void main(String[] args){
}
public void buyFish(){
System.out.println("Buy fishes at low cost");
}
}

├── KasimeduMarket.java
└── chennai
├── north
│ └── KasimeduMarket.class
└── south
└── KoyambeduMarket.class

Import and how to call a method in differrent package

CODE EXAMPLE

package chennai.north;
import chennai.south.KoyambeduMarket;
public class Anna_Nagar
{
public static void main(String[] args){

KoyambeduMarket vegetables = new KoyambeduMarket();
vegetables.buyVeg();

KasimeduMarket fish = new KasimeduMarket();
fish.buyFish();
}
}

Java
├── Anna_Nagar.java
├── KoyambeduMarket.java
├── KasimeduMarket.java
└── chennai
├── north
│ ├── Anna_Nagar.class
│ └── KasimeduMarket.class
└── south
└── KoyambeduMarket.class

Working Flow of the code

STEP 1. Create Package :
package chennai.north;

STEP 2. Import statement :
import chennai.south.KoyambeduMarket;

✓ Because java dosen't know the KoyambeduMarket class its exist in sub-package south, its know the same sub-package classes only

• Example its know the all classes existing in north,beacuse Anna_Nagar class existing innorth`.

✓ Java brings the KoyambeduMarket class from another package (chennai.south) into this file.

STEP 3. Create first object :
KoyambeduMarket vegetables = new KoyambeduMarket();

✓ Memory is allocated for a KoyambeduMarket object.

✓ Variable vegetables stores in the object.

STEP 4. Call the method :
vegetables.buyVeg();

✓ The buyVeg() method executes and prints the message
"Buy vegetables at low cost"

STEP 5. Create second object :
KasimeduMarket fish = new KasimeduMarket();

✓ A new KasimeduMarket object is created and variable fish stored in the object .

STEP 6. Call second method :
fish.buyFish();

✓ The buyFish() method executes and prints the message
"Buy fishes at low cost"

Output