Built-in and User-defined packages
Java Program (Greeting.java) 

// Greeting.java (inside mypackage folder)

package mypackage;

public class Greeting
{
    public void sayHello()
    {
        System.out.println("Hello from the user-defined package!");
    }
}
Java Program (Example.java) 

// Example.java

import java.util.Scanner;
import mypackage.Greeting;

public class Example
{
    public static void main(String[] args)
    {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter your name: ");
        String name = scanner.nextLine();

        System.out.println("Hello, " + name + "!");

        Greeting greeting = new Greeting();
        greeting.sayHello();
    }
}