Claude Code Tutorial: How to Install and Use Claude Code in 2026

Introduction

Claude Code is Anthropic's AI coding agent that works directly with your software projects. It can read files, edit code, run commands, analyze errors, write tests, and help you complete development tasks from your terminal.

Unlike a normal AI chatbot, Claude Code can work with your actual project and development environment.

In this tutorial, you'll learn how to install Claude Code, open a project, authenticate, give it instructions, make code changes, run tests, and use it safely in a real development workflow.

Quick Answer

Claude Code is an AI coding agent from Anthropic that lets developers work with their codebase directly from the terminal.

You can use it to:

• Understand an existing project

• Create and edit files

• Fix bugs

• Run commands

• Write tests

• Refactor code

• Explain unfamiliar code

• Work with Git

• Build features

• Analyze errors

Claude Code supports macOS, Windows, Linux, and WSL.

What Is Claude Code?

Claude Code is designed to act more like a coding agent than a traditional chatbot.

Instead of copying your code into a browser and asking for help, you start Claude Code inside your project.

For example:

cd my-project
claude

You can then ask it to inspect your project:

Explain the structure of this project and tell me
where the REST API controllers are.

Claude Code can inspect the project and explain what it finds.

You can also give it a development task:

Add a login endpoint using Spring Security and JWT.

Claude Code can inspect the existing application, identify relevant files, make changes, and run appropriate commands.

Why Use Claude Code?

The biggest advantage of Claude Code is context.

With a normal chatbot, you often have to paste files or explain your project structure.

Claude Code works directly inside your project, so it can understand the files, code, and development environment around your task.

You can use Claude Code to:

• Understand your codebase — Analyze project structure and explain how different components work.

• Create files — Generate controllers, services, components, tests, configuration files, and more.

• Edit files — Modify existing code based on your requirements.

• Run terminal commands — Execute build, test, and development commands when permitted.

• Debug errors — Analyze stack traces and investigate the cause of failures.

• Write tests — Generate and update unit or integration tests.

• Refactor code — Improve existing code while following your project structure.

• Explain code — Break down unfamiliar classes, functions, and workflows.

• Work with Git — Review changes and assist with Git-based development workflows.

The important difference is that Claude Code isn't limited to answering questions.

It can work with your actual development environment.

How Claude Code Works

The basic workflow looks like this:

Your Project
     ↓
Claude Code
     ↓
Reads Project Context
     ↓
Plans the Task
     ↓
Edits Files / Runs Commands
     ↓
Tests the Changes
     ↓
You Review the Result

The important part is that you remain in control.

Don't blindly accept every change.

Review the code, especially when Claude modifies authentication, database queries, infrastructure, or production configuration.

Claude Code Requirements

Before installing Claude Code, make sure your system meets the basic requirements.

You'll generally need:

• Windows 10 1809 or newer, macOS 13+, Ubuntu 20.04+, or a supported Linux distribution

• At least 4 GB RAM

• Internet connection

• 64-bit x64 or ARM64 system

• An eligible Claude account or supported API/provider setup

Windows users can use Claude Code natively or through WSL.

Git for Windows is recommended for native Windows setups.

How to Install Claude Code on Windows

If you're using Windows, the easiest installation method is the native installer.

Open PowerShell and run:

irm https://claude.ai/install.ps1 | iex

After installation, close and reopen your terminal.

Then verify the installation:

claude --version

You can also check your installation with:

claude doctor

The claude doctor command is useful when you need to diagnose installation or configuration problems.

Install Claude Code Using WinGet

Windows users can also install Claude Code through WinGet:

winget install Anthropic.ClaudeCode

Then verify:

claude --version

To update the WinGet installation later:

winget upgrade Anthropic.ClaudeCode

Install Claude Code on macOS or Linux

For macOS, Linux, or WSL, you can use the native installer:

curl -fsSL https://claude.ai/install.sh | bash

After installation:

claude --version

Start Claude Code with:

claude

You can also use supported package-manager installation methods depending on your operating system.

Step 1: Open Your Project

Let's assume you have a Java Spring Boot project.

Navigate to the project:

cd my-spring-boot-app

Then start Claude Code:

claude

On the first launch, Claude Code will guide you through authentication.

Once authentication is complete, Claude Code is ready to work with your project.

Step 2: Ask Claude Code to Understand Your Project

Don't immediately ask it to change code.

Start with something simple:

Analyze this project and explain its architecture.
Do not modify any files.

This is a good habit.

You'll understand what Claude sees before allowing it to make changes.

For a Spring Boot project, you could ask:

Explain the controller, service, repository,
and entity layers in this project.

Do not modify anything.

Claude can inspect the project and explain how the different layers work together.

Step 3: Ask Claude Code to Make a Change

Now give it a small, specific task.

For example:

Create a GET /api/users endpoint that returns
all users.

Follow the existing project structure
and coding conventions.

Claude may inspect files such as:

UserController
UserService
UserRepository
User

and determine where the required changes belong.

Before accepting the changes, review what it wants to modify.

Step 4: Let Claude Run Tests

After making a code change, ask:

Run the project's tests and fix any failures.

For a Maven project, the command might be:

./mvnw test

or:

mvn test

For a Node.js project:

npm test

The exact command depends on your project.

The important workflow is:

Make Change
     ↓
Run Tests
     ↓
Find Failures
     ↓
Fix Problems
     ↓
Run Tests Again

Don't consider the task finished just because the code looks correct.

A Real Claude Code Example

Suppose your Spring Boot application has this structure:

src/
 └── main/
     └── java/
         └── com.example.app/
             ├── controller/
             ├── service/
             ├── repository/
             └── entity/

You could ask Claude:

Add pagination to the GET /api/users endpoint.

Use Spring Data Pageable.

Keep the existing response structure if possible.

Add or update tests for the endpoint.

Do not change unrelated files.

This is much better than:

Make my API better.

The first prompt gives Claude a clear goal, constraints, and expected result.

Useful Claude Code Commands

You'll frequently use a few basic commands.

Start Claude Code

claude

Check the installed version

claude --version

Diagnose installation

claude doctor

Update Claude Code

claude update

Get help

Inside Claude Code:

/help

Claude Code evolves quickly, so check the official documentation when a command behaves differently in a newer release.

How to Write Better Claude Code Prompts

This is where beginners often struggle.

Don't write:

Fix my application.

That's too vague.

Instead, give Claude context and constraints:

The login endpoint returns HTTP 401 after
successful authentication.

Inspect the authentication flow.

Identify the root cause.

Fix only the required files.

Run the relevant tests afterward.

Explain what caused the problem.

A useful coding-agent prompt usually contains:

Goal
↓
Context
↓
Constraints
↓
Expected Result
↓
Validation

For example:

Goal:
Add JWT authentication.

Context:
This is a Spring Boot 3 application.

Constraints:
Use the existing security configuration.
Don't change unrelated endpoints.

Validation:
Run the authentication tests and explain the result.

The more clearly you describe the task, the less guessing Claude has to do.

Claude Code With Git

Claude Code can also be useful inside Git repositories.

Before making a large change, check your current Git state:

git status

Then ask Claude:

Review the current Git changes and explain
what has been modified.

Don't change anything.

After making changes, inspect the diff:

git diff

Review the changes yourself.

A good workflow is:

Claude Code
     ↓
Make Change
     ↓
Run Tests
     ↓
git diff
     ↓
Review
     ↓
Commit

Don't let an AI agent become an excuse to stop reviewing your own code.

Claude Code With Java and Spring Boot

Claude Code is especially useful for backend development.

You can ask it to:

• Create REST controllers

• Generate service classes

• Create DTOs

• Create JPA repositories

• Add validation

• Write unit tests

• Debug Spring errors

• Analyze stack traces

• Refactor services

• Create API documentation

• Review SQL queries

• Explain Spring Security configuration

For example:

Review this Spring Boot authentication implementation.

Check for:

1. Security problems
2. Incorrect JWT handling
3. Password handling
4. Exception handling
5. Test coverage

Do not modify the code.

This makes Claude useful not only for generating code, but also for learning and code review.

CLAUDE.md: Give Claude Project Instructions

One useful feature is the CLAUDE.md file.

You can use it to store project-specific instructions that Claude should follow.

For example:

# Project Instructions

- Use Java 21.
- Use Spring Boot 3.
- Use Maven.
- Follow the existing package structure.
- Use constructor injection.
- Write tests for new services.
- Do not modify database migrations without approval.

This means you don't have to repeat the same project rules every time.

For a large codebase, project instructions can make AI-assisted development much more consistent.

Claude Code and MCP

Claude Code can also work with MCP-based integrations.

MCP, or Model Context Protocol, allows AI applications to connect with external tools and data sources.

The basic idea looks like this:

Claude Code
     ↓
MCP
     ↓
External Tool or Service

This can extend an AI coding workflow beyond local project files.

For example, an MCP server could provide access to external systems, documentation, databases, or development tools.

MCP is an important topic for developers building AI-powered applications, and we'll cover it separately on TheTechLane.

Claude Code vs Traditional AI Chat

A traditional AI chatbot is mainly designed for conversations, explanations, and generating code from the context you provide.

Claude Code is designed for a more direct software-development workflow.

Traditional AI Chat

• You usually provide the code or files manually.

• You ask questions through a chat interface.

• You generally copy generated code back into your project.

• Running tests is usually your responsibility.

• The AI has limited awareness of your local project.

Claude Code

• Works directly inside your project.

• Can inspect project files.

• Can create and modify files.

• Can run development commands.

• Can help debug errors.

• Can run tests.

• Can work inside Git repositories.

• Can use project-specific instructions through CLAUDE.md.

So the main difference isn't simply code generation.

It's the ability to move from:

Ask → Copy → Paste → Test

to:

Ask → Inspect → Implement → Test → Review

Common Claude Code Mistakes

1. Giving Vague Instructions

Bad:

Fix everything.

Better:

Fix the NullPointerException in UserService.

Run the related tests afterward.

Don't modify unrelated files.

Specific instructions produce more predictable results.

2. Accepting Every Change

AI-generated code still needs review.

Always inspect changes with:

git diff

Then run your tests.

3. Giving Too Much Responsibility

Don't start with:

Rewrite my entire application.

Start with one well-defined task.

Once you're comfortable with Claude Code, you can gradually increase the scope.

4. Ignoring Project Conventions

Tell Claude what technologies and patterns your project uses.

For example:

Use Java 21,
Spring Boot 3,
constructor injection,
and JUnit 5.

This gives the agent useful constraints.

5. Not Testing the Result

Generated code isn't finished until you've validated it.

For a Maven project:

mvn test

For a Node.js project:

npm test

Always use the appropriate validation command for your project.

Claude Code Best Practices

For a reliable workflow:

• Start with small tasks.

• Give clear requirements.

• Tell Claude what it shouldn't modify.

• Ask it to explain important changes.

• Run tests after modifications.

• Review Git diffs.

• Keep project instructions in CLAUDE.md.

• Never expose API keys or secrets unnecessarily.

• Be careful with production systems.

• Don't blindly execute destructive commands.

The goal isn't to let Claude control your entire development environment.

The goal is to make you faster while keeping yourself in control.

Is Claude Code Worth Learning?

Yes, especially if you're a developer working with:

• Java

• Spring Boot

• React

• JavaScript

• Python

• Node.js

• REST APIs

• Git

• Docker

• AI applications

But there's an important distinction.

Learning Claude Code isn't just about learning prompts.

The valuable skill is learning how to direct an AI coding agent.

Instead of:

"Write this code for me."

Think:

"Here's the problem, the constraints, the expected behavior, and how we can validate the result."

That's much closer to how AI-assisted software development works in practice.

Try It Yourself

Create a small project and give Claude Code this task:

Create a simple REST API for managing tasks.

Requirements:

- Use Spring Boot.
- Create a Task entity.
- Create controller, service, and repository layers.
- Add CRUD operations.
- Add validation.
- Add tests.
- Explain the project structure.
- Run the tests after implementation.

Then inspect every file it creates.

Run the application.

Test the endpoints.

Read the generated code.

Don't just look at whether the application works.

Try to understand why the generated code works.

That's where the real learning happens.

Claude Code FAQ

Is Claude Code free?

Claude Code access depends on the Claude plan or supported developer/provider setup you're using. Check Anthropic's current pricing and Claude Code documentation for the latest availability.

Can I use Claude Code on Windows?

Yes. Claude Code supports Windows, including native Windows and WSL workflows.

Do I need Node.js to use Claude Code?

The current native installation doesn't require Node.js. An npm-based installation is also available for supported setups.

Can Claude Code modify my files?

Yes. Modifying files is one of its core capabilities. Always review changes before accepting them.

Can Claude Code run terminal commands?

Yes. Claude Code can work with terminal commands as part of its coding workflow.

Can I use Claude Code with Java?

Yes. It can work with Java projects, including Maven- and Gradle-based applications.

Can I use Claude Code with Spring Boot?

Yes. It can help create controllers, services, repositories, tests, configuration, and debug Spring Boot applications.

Does Claude Code work with GitHub?

Claude Code can work inside Git repositories and assist with Git-based development workflows.

What is CLAUDE.md?

CLAUDE.md is a project instruction file that provides Claude with project-specific rules, conventions, and context.

Is Claude Code better than an AI chatbot?

They're designed for different workflows. A chatbot is useful for questions and explanations, while Claude Code is designed to work directly with software projects and development tools.

Key Takeaways

• Claude Code is Anthropic's AI coding agent.

• It works directly with your development project.

• It can read files, edit code, run commands, and help test changes.

• It supports Windows, macOS, Linux, and WSL.

• Start Claude Code inside a project with claude.

• Give it specific tasks instead of vague instructions.

• Review generated changes before accepting them.

• Use Git and tests to validate AI-generated code.

• CLAUDE.md can store project-specific instructions.

• Claude Code is useful for Java, Spring Boot, React, backend, and AI development.

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