Packages

Packages in Java

A package is used to group related classes and interfaces into a single unit.

Examples

• Database classes → java.sql
• File I/O classes → java.io

Package concept illustration

Advantages

• Avoid name conflicts
• Better organization
• Improved security

Use reverse domain naming: com.example.project

Naming Example

com.icicibank.loan.housing.Account

• com.icicibank → domain
• loan → module
• housing → sub-module
• Account → class

Example Program

package com.code.java;

public class Test {
    public static void main(String[] args) {
        System.out.print("hello");
    }
}

Compilation

Normal:

javac Test.java

With package folders:

javac -d . Test.java

If directory does not exist, compilation will fail.

Important Rules

• Only one package statement allowed
• It must be the first line
• Order: package → import → class