Creating packages in Java

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Introduction

Packages help organize your Java code into neat folders. They keep related classes together and avoid name clashes.

When you want to group related classes like all shapes or all animals.

When your project grows and you need to keep code organized.

When you want to avoid conflicts between classes with the same name.

When sharing your code with others to keep it tidy and easy to use.

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Syntax

Java

package package_name;

public class ClassName {
    // class code here
}

The package statement must be the very first line in your Java file.

Package names are usually all lowercase and use dots to separate levels, like com.example.app.

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Examples

line_end_arrow_notchThis creates a package named animals and a class Dog inside it.

Java

package animals;

public class Dog {
    public void bark() {
        System.out.println("Woof!");
    }
}

line_end_arrow_notchA deeper package com.example.utils to organize utility classes.

Java

package com.example.utils;

public class MathHelper {
    public static int add(int a, int b) {
        return a + b;
    }
}

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Sample Program

This program defines a package called greetings and prints a message from inside it.

Java

package greetings;

public class Hello {
    public static void main(String[] args) {
        System.out.println("Hello from the greetings package!");
    }
}

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Important Notes

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When you compile, place your files in folders matching the package name (e.g., greetings/Hello.java).

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To run the program, use the full class name with package: java greetings.Hello.

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Summary

Packages group related classes to keep code organized.

Use the package statement at the top of your Java file.

Package names use lowercase letters and dots to separate levels.