1. Built-in Packages (like java.util, java.io, java.lang)
2. User-defined Packages (created by the programmer)

• Organizes classes logically (e.g., utility classes, model classes).
• Avoids class name conflicts between different modules or developers.
• Provides access protection (using public, protected, private).
• Makes searching, locating, and using classes/interfaces easier.

• package package_name;
  • This should always be the first statement in our Java file.

• 1. import package_name.class_name;
  • It is used to import only a specific class from a package.
• 2. import package_name.*;
  • It is used to import all classes from a package.
• Import statement should always be the first statement after the package declaration.

import java.util.Scanner;

public class MainApp
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter your name: ");
        String name = sc.nextLine();
        System.out.println("Hello, " + name);
    }
}

Enter your name: Deepak
Hello, Deepak

package p1;

public class MyClass
{
    public void display()
    {
        System.out.println("Hello from MyClass in p1 package.");
    }
}

package p2;

import p1.MyClass;  // Importing MyClass from p1 package

public class MainApp
{
    public static void main(String[] args)
    {
        MyClass obj = new MyClass();
        obj.display();
    }
}

Hello from MyClass in p1 package.

• javac p1/MyClass.java      # Compile the package class
  javac -cp . p2/MainApp.java      # Compile the main class using current dir as classpath
  java p2.MainApp     # Run the program