### Resend Java SDK - Configuration and Setup

Source: https://github.com/resend/resend-java/blob/main/_autodocs/GENERATION-SUMMARY.txt

Guidance on setting up the Resend Java SDK, including environment variable configuration, HTTP client setup, and application integration examples.

```APIDOC
## Configuration and Setup (`configuration.md`)

This section details how to configure and set up the Resend Java SDK for your application.

### Key Topics:
- **Environment variable setup**: Instructions for configuring Resend using environment variables.
- **HTTP client configuration**: Details on customizing the underlying HTTP client.
- **Dependency list**: Information on required libraries and dependencies.
- **Performance tuning**: Tips for optimizing SDK performance.
- **Security best practices**: Recommendations for secure usage.
- **Application setup examples**: Demonstrations for integrating with popular frameworks like Spring Boot and standalone applications.
```

--------------------------------

### Create API Key with Specific Permissions

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/apikeys-service.md

Example of creating an API key with a defined set of permissions for specific operations.

```java
CreateApiKeyOptions options = new CreateApiKeyOptions();
options.setName("Mobile App Key");
options.setPermissions(Arrays.asList(
    "sending:write",
    "emails:read",
    "contacts:read",
    "contacts:write"
));

CreateApiKeyResponse response = resend.apiKeys().create(options);

// Store the key securely (use environment variables or secrets manager)
System.setProperty("MOBILE_APP_API_KEY", response.getToken());
```

--------------------------------

### Full Template Workflow Example

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Demonstrates the complete lifecycle of a template: creation, optional updating, publishing, and subsequent use in sending an email. This covers all essential template management operations.

```java
// Step 1: Create template
CreateTemplateOptions createOptions = new CreateTemplateOptions();
createOptions.setName("Order Confirmation");
createOptions.setSubject("Your order #{{order_id}} is confirmed");
createOptions.setHtmlPart(
    "<h1>Order Confirmed</h1>" +
    "<p>Hi {{customer_name}},</p>" +
    "<p>Your order {{order_id}} has been received.</p>" +
    "<p>Total: {{total_amount}}</p>"
);

CreateTemplateResponseSuccess created = resend.templates().create(createOptions);
String templateId = created.getId();

// Step 2: Update if needed
UpdateTemplateOptions updateOptions = new UpdateTemplateOptions();
updateOptions.setHtmlPart("<h1>Order Confirmed</h1><p>Updated content</p>");
resend.templates().update(templateId, updateOptions);

// Step 3: Publish
PublishTemplateResponseSuccess published = resend.templates().publish(templateId);
System.out.println("Template published and ready to use");

// Step 4: Use in emails
Template template = Template.builder()
    .id(published.getId())
    .addVariable("order_id", "ORD-123456")
    .addVariable("customer_name", "John Doe")
    .addVariable("total_amount", "$99.99")
    .build();

CreateEmailOptions emailOptions = CreateEmailOptions.builder()
    .from("orders@example.com")
    .to("john@example.com")
    .template(template)
    .build();

CreateEmailResponse emailResponse = resend.emails().send(emailOptions);
```

--------------------------------

### Create Email Automation

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Example of how to create an email automation using the automations service. Requires a Resend client instance and automation options.

```java
CreateAutomationResponseSuccess automation = resend.automations().create(options);

```

--------------------------------

### List Email Events

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Example of how to list email events using the events service. Requires a Resend client instance.

```java
ListEventsResponse events = resend.events().list();

```

--------------------------------

### Thread-Safe SDK Usage Example

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Demonstrates how to safely use a single `Resend` client instance across multiple threads for concurrent API operations.

```java
// Single shared instance
Resend resend = new Resend(apiKey);

// Safe to use from multiple threads
ExecutorService executor = Executors.newFixedThreadPool(10);

for (int i = 0; i < 100; i++) {
    final int index = i;
    executor.submit(() -> {
        try {
            resend.emails().send(createEmailOptions(index));
        } catch (ResendException e) {
            logger.error("Send failed", e);
        }
    });
}
```

--------------------------------

### Manage Template Versions

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Demonstrates how to get the current template version, duplicate an existing template to create a new version, update the new version's content, and publish it.

```java
// Get current template
GetTemplateResponseSuccess template = resend.templates().get("tmpl_123");
System.out.println("Version: " + template.getVersion());

// Create a new version by duplicating
DuplicateTemplateResponseSuccess copy = resend.templates().duplicate("tmpl_123");
System.out.println("New version created: " + copy.getId());

// Update the copy
UpdateTemplateOptions options = new UpdateTemplateOptions();
options.setHtmlPart("<h1>New Version Content</h1>");
resend.templates().update(copy.getId(), options);

// Publish when ready
resend.templates().publish(copy.getId());
```

--------------------------------

### List Email Activity Logs

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Example of how to list email activity logs using the logs service. Requires a Resend client instance.

```java
ListLogsResponse logs = resend.logs().list();

```

--------------------------------

### get() - Retrieve Template

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Retrieves a template by its ID or alias.

```APIDOC
## get() - Retrieve Template

Retrieves a template by ID or alias.

### Method
GET

### Endpoint
/templates/{templateId}

### Parameters
#### Path Parameters
- **templateId** (String) - Required - Template ID or alias

### Response
#### Success Response (200)
- **id** (String) - The unique identifier of the template.
- **name** (String) - The name of the template.
- **subject** (String) - The subject of the template, can include variables.
- **html_part** (String) - The HTML content of the template.
- **text_part** (String) - The plain text content of the template.
- **variables** (Object) - An object containing template variables.
- **alias** (String) - An optional alias for the template.
- **created_at** (String) - The timestamp when the template was created.
- **updated_at** (String) - The timestamp when the template was last updated.

### Response Example
```json
{
  "id": "tmpl_abc123",
  "name": "Welcome Email",
  "subject": "Welcome {{first_name}}!",
  "html_part": "<h1>Hello {{first_name}}</h1><p>Welcome to our service!</p>",
  "text_part": "Hello {{first_name}}!\nWelcome to our service!",
  "variables": {},
  "alias": "welcome-email",
  "created_at": "2023-10-27T10:00:00Z",
  "updated_at": "2023-10-27T10:05:00Z"
}
```
```

--------------------------------

### Resend Constructor

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Initializes the Resend client with your API key. This is the primary way to start using the Resend Java SDK.

```APIDOC
## Resend Constructor

### Description
Initializes the Resend client with your API key. This is the primary way to start using the Resend Java SDK.

### Method Signature
```java
public Resend(String apiKey)
```

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Parameters Table
| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| apiKey | String | Yes | — | API key from Resend Dashboard for authentication |
```

--------------------------------

### Resend Java SDK - Overview

Source: https://github.com/resend/resend-java/blob/main/_autodocs/GENERATION-SUMMARY.txt

This section outlines the structure and content of the Resend Java SDK documentation, guiding users on how to navigate and utilize the provided resources.

```APIDOC
## Resend Java SDK Documentation Structure

This documentation is organized to help both new and experienced users effectively leverage the Resend Java SDK.

### For New Users:
1. **00-START-HERE.md**: Begin with this file for a quick introduction and navigation guide.
2. **README.md**: Provides a project overview and quick start examples.
3. **Quick Examples**: Follow the provided examples to get started quickly.
4. **Service Docs**: Reference specific service documentation as needed.

### For Developers:
1. **INDEX.md**: Use this file to locate specific methods.
2. **Service Files**: Navigate to the relevant service file (e.g., `emails-service.md`) for detailed method documentation.
3. **Code Examples**: Copy and adapt the provided code examples.
4. **types.md**: Refer to this file for information on data types.
5. **errors.md**: Consult this file for details on error handling.

### For API Lookup:
1. **INDEX.md**: Find the desired method.
2. **Service File**: Read the detailed documentation for the method.
3. **types.md**: Understand the associated data types.
4. **errors.md**: Learn how to handle potential exceptions.

### For Setup:
1. **configuration.md**: Find instructions for environment setup.
2. **README.md**: Review quick examples for initial setup.
3. **errors.md**: Understand error handling during setup.
4. **Service Docs**: Refer to specific service documentation for implementation details.
```

--------------------------------

### Resend Java SDK - API Reference Files

Source: https://github.com/resend/resend-java/blob/main/_autodocs/GENERATION-SUMMARY.txt

Detailed documentation for each service within the Resend Java SDK, including method signatures, code examples, and workflow patterns.

```APIDOC
## API Reference Files

The Resend Java SDK provides comprehensive API reference documentation for each service, ensuring clarity and ease of use.

### Available Service Files:
- **resend-client.md**: Documentation for the main Resend client.
- **emails-service.md**: Documentation for Email operations.
- **batch-service.md**: Documentation for Batch email sending.
- **contacts-service.md**: Documentation for Contact management.
- **domains-service.md**: Documentation for Domain management.
- **templates-service.md**: Documentation for Template management.
- **apikeys-service.md**: Documentation for API key management.
- **core-utilities.md**: Documentation for infrastructure classes.

### Content per Service File:
- **Complete method documentation**: Detailed signatures and descriptions for all public methods.
- **Real code examples**: Runnable examples demonstrating method usage.
- **Workflow patterns**: Guidance on common usage scenarios.
- **Related types**: Links to type definitions in `types.md`.
- **Error handling per method**: Specific error scenarios and handling strategies for each method.
```

--------------------------------

### Send Email using Resend Java SDK

Source: https://github.com/resend/resend-java/blob/main/README.md

This example demonstrates how to send an email using the Resend Java SDK. It includes setting sender, recipients (to, cc, bcc), reply-to, subject, and body. Ensure you have your API key and necessary imports.

```java
package com.resend;

import com.resend.services.emails.model.*;
import com.resend.core.provider.AuthenticationProvider;
import com.resend.core.provider.impl.AuthenticationProviderStandard;
import com.resend.services.emails.ResendEmails;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_123");

        CreateEmailOptions params = CreateEmailOptions.builder()
                .from("Me <me@exemple.io>")
                .to("to@example", "you@example.com")
                .cc("carbon@example.com", "copy@example.com")
                .bcc("blind@example.com", "carbon.copy@example.com")
                .replyTo("reply@example.com", "to@example.com")
                .text("Hello, world!")
                .subject("Hello from Java!")
                .build();

        try {
            CreateEmailResponse data = resend.emails().send(params);
            System.out.println(data.getId());
        } catch (ResendException e) {
            e.printStackTrace();
        }
    }
}
```

--------------------------------

### List All Email Attachments

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/emails-service.md

Lists all attachments for a given email. Use this to get a list of all associated files.

```java
public ListAttachmentsResponse listAttachments(String emailId) throws ResendException
```

```java
ListAttachmentsResponse response = resend.emails().listAttachments("email_123");
for (AttachmentResponse att : response.getAttachments()) {
    System.out.println(att.getFileName());
}
```

--------------------------------

### Send an Email

Source: https://github.com/resend/resend-java/blob/main/_autodocs/00-START-HERE.md

Example of sending a single email using the Resend Java SDK. Ensure you have initialized the Resend client with your API key.

```java
Resend resend = new Resend("re_123");

CreateEmailOptions options = CreateEmailOptions.builder()
    .from("sender@example.com")
    .to("recipient@example.com")
    .subject("Hello!")
    .text("Body")
    .build();

try {
    CreateEmailResponse response = resend.emails().send(options);
    System.out.println("Email sent: " + response.getId());
} catch (ResendException e) {
    System.err.println("Error: " + e.getMessage());
}
```

--------------------------------

### Example: Handling 404 Not Found

Source: https://github.com/resend/resend-java/blob/main/_autodocs/errors.md

Illustrates attempting to retrieve a non-existent email ID, which results in a 404 Not Found error. The `ResendException` will report `statusCode: 404` and `errorName: "not_found"`.

```java
try {
    resend.emails().get("nonexistent_email_id");
} catch (ResendException e) {
    // statusCode: 404
    // errorName: "not_found"
    // message: "Email not found"
}
```

--------------------------------

### Example: Handling 401 Unauthorized (Authentication Error)

Source: https://github.com/resend/resend-java/blob/main/_autodocs/errors.md

Shows how to trigger a 401 Unauthorized error by using an invalid API key. The `ResendException` will have `statusCode: 401` and `errorName: "authentication_error"`.

```java
Resend resend = new Resend("invalid_key_xyz");

try {
    resend.emails().list();
} catch (ResendException e) {
    // statusCode: 401
    // errorName: "authentication_error"
    // message: "Unauthorized"
}
```

--------------------------------

### Use Batch API for High Volume

Source: https://github.com/resend/resend-java/blob/main/_autodocs/README.md

Send emails in batches to handle high volumes efficiently. This example shows how to send 100 emails at a time, up to 1000 total.

```java
List<CreateEmailOptions> batch = new ArrayList<>();
for (int i = 0; i < 1000; i++) {
    batch.add(createEmail(i));
    if (batch.size() == 100) {
        resend.batch().send(batch);
        batch.clear();
    }
}
```

--------------------------------

### Example: Handling 400 Bad Request (Validation Error)

Source: https://github.com/resend/resend-java/blob/main/_autodocs/errors.md

Demonstrates sending an email with invalid 'from' address, triggering a 400 Bad Request error. The `ResendException` will contain `statusCode: 400` and `errorName: "validation_error"`.

```java
CreateEmailOptions options = CreateEmailOptions.builder()
    .from("invalid")  // Missing domain
    .to("recipient@example.com")
    .subject("Test")
    .text("Body")
    .build();

try {
    resend.emails().send(options);
} catch (ResendException e) {
    // statusCode: 400
    // errorName: "validation_error"
    // message: "Invalid email format: invalid"
}
```

--------------------------------

### Handle 500/503 Server Errors with Fallback

Source: https://github.com/resend/resend-java/blob/main/_autodocs/errors.md

Implement a fallback mechanism for server errors (5xx status codes). This example logs the error and queues the email for a later asynchronous retry.

```java
try {
    resend.emails().send(options);
} catch (ResendException e) {
    if (e.getStatusCode() >= 500) {
        // Server error - log and retry later
        logger.error("Server error sending email: " + e.getMessage());
        queueForRetry(options); // Store in queue for async retry
    } else {
        throw e; // Client error - don't retry
    }
}
```

--------------------------------

### Emails Service - Get Email

Source: https://github.com/resend/resend-java/blob/main/_autodocs/INDEX.md

Retrieves the details of a specific email using its ID.

```APIDOC
## get()

### Description
Retrieves the details of a specific email.

### Method
`get(String emailId)`

### Parameters
#### Path Parameters
- **emailId** (String) - Required - The ID of the email to retrieve.
```

--------------------------------

### Initialize Resend Client with API Key from Environment Variable

Source: https://github.com/resend/resend-java/blob/main/_autodocs/configuration.md

Demonstrates the recommended way to initialize the Resend client by securely retrieving the API key from an environment variable.

```java
// ✓ GOOD: Use environment variable
Resend resend = new Resend(System.getenv("RESEND_API_KEY"));
```

--------------------------------

### Domain Verification Workflow

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/domains-service.md

Illustrates the typical workflow for setting up a domain, including creation, DNS record retrieval, and verification. It involves creating a domain, fetching its DNS records, configuring them with a DNS provider, waiting for propagation, and then verifying the domain.

```java
// Step 1: Create the domain
CreateDomainOptions createOptions = new CreateDomainOptions();
createOptions.setDomain("mail.mycompany.com");
CreateDomainResponse createResponse = resend.domains().create(createOptions);

// Step 2: Get DNS records and configure them in your DNS provider
Domain domain = resend.domains().get(createResponse.getId());
System.out.println("Add these DNS records to your DNS provider:");
for (DnsRecord record : domain.getDnsRecords()) {
    System.out.println("Type: " + record.getType());
    System.out.println("Name: " + record.getName());
    System.out.println("Value: " + record.getValue());
}

// Step 3: After DNS propagation (typically 15-30 minutes), verify
Thread.sleep(5 * 60 * 1000); // Wait 5 minutes
VerifyDomainResponse verifyResponse = resend.domains().verify(domain.getId());

if ("success".equals(verifyResponse.getStatus())) {
    System.out.println("Domain verified successfully!");
} else {
    System.out.println("Domain verification still pending: " + verifyResponse.getStatus());
}
```

--------------------------------

### Get HTTP Status Code

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Retrieves the integer status code from an HTTP response.

```java
public int getCode()
```

--------------------------------

### get() - Retrieve Email

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/emails-service.md

Retrieves the details of a previously sent email using its unique identifier.

```APIDOC
## get() - Retrieve Email

### Description
Retrieves the details of a previously sent email using its unique identifier.

### Method
```java
public Email get(String emailId)
```

### Parameters
#### Path Parameters
- **emailId** (String) - Required - Unique identifier of the email to retrieve

#### Query Parameters
None

#### Request Body
None

### Request Example
```java
Email email = resend.emails().get("email_123abc");
System.out.println("To: " + email.getTo());
System.out.println("Subject: " + email.getSubject());
System.out.println("Created: " + email.getCreatedAt());
```

### Response
#### Success Response
- **Email** - Complete email details including content, recipients, and metadata

#### Response Example
(Response structure not detailed in source, only return type is mentioned)

### Throws
- **ResendException** - If the email does not exist or request fails
```

--------------------------------

### Service Instantiation for Operations

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Illustrates creating service instances (e.g., `Emails`) on a per-operation basis, highlighting their lightweight and thread-safe nature.

```java
// Services are lightweight, safe to create per-operation
public void sendEmail(CreateEmailOptions options) throws ResendException {
    Emails emailsService = resend.emails();
    return emailsService.send(options);
}
```

--------------------------------

### Constructor

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Initializes the Templates service with an API key for authentication.

```APIDOC
## Constructor

```java
public Templates(String apiKey)
```

### Parameters
#### Path Parameters
- **apiKey** (String) - Required - API key for authentication
```

--------------------------------

### get() - Retrieve Domain

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/domains-service.md

Retrieves details about a specific sending domain using its unique identifier.

```APIDOC
## get() - Retrieve Domain

### Description
Retrieves details about a specific sending domain.

### Method
GET

### Endpoint
/domains/{domain_id}

### Parameters
#### Path Parameters
- **domain_id** (string) - Required - Unique identifier of the domain

### Response
#### Success Response (200)
- **id** (string) - The unique identifier for the domain.
- **domain** (string) - The domain name.
- **status** (string) - The verification status of the domain.
- **created_at** (string) - The timestamp when the domain was created.
- **dns_records** (object) - DNS records associated with the domain (may be null if verified).

#### Response Example
```json
{
  "id": "domain_abc123",
  "domain": "mail.example.com",
  "status": "verified",
  "created_at": "2023-10-27T10:00:00Z",
  "dns_records": null
}
```
```

--------------------------------

### Initialize Email Service with API Key

Source: https://github.com/resend/resend-java/blob/main/_autodocs/configuration.md

Instantiates the Resend client using an API key from environment variables. Throws an exception if the API key is not found.

```java
public class EmailService {
    private final Resend resend;
    
    public EmailService() {
        String apiKey = System.getenv("RESEND_API_KEY");
        if (apiKey == null || apiKey.isEmpty()) {
            throw new IllegalStateException("RESEND_API_KEY environment variable not set");
        }
        this.resend = new Resend(apiKey);
    }
    
    public void sendWelcomeEmail(String recipientEmail) throws ResendException {
        CreateEmailOptions options = CreateEmailOptions.builder()
            .from("welcome@myapp.com")
            .to(recipientEmail)
            .subject("Welcome!")
            .text("Thanks for signing up")
            .build();
            
        resend.emails().send(options);
    }
}
```

--------------------------------

### Get Resend SDK Version

Source: https://github.com/resend/resend-java/blob/main/_autodocs/configuration.md

Retrieves the current version of the Resend SDK being used in the project.

```java
String version = SdkVersion.getVersion();
System.out.println("Resend SDK Version: " + version);
```

--------------------------------

### Constructor

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/contacts-service.md

Initializes the Contacts service with an API key for authentication.

```APIDOC
## Constructor

### Description
Initializes the Contacts service with an API key for authentication.

### Parameters
#### Path Parameters
- **apiKey** (String) - Required - API key for authentication
```

--------------------------------

### Emails Service - Get Attachment

Source: https://github.com/resend/resend-java/blob/main/_autodocs/INDEX.md

Retrieves a single attachment for a given email ID and attachment ID.

```APIDOC
## getAttachment()

### Description
Retrieves a single attachment for an email.

### Method
`getAttachment(String emailId, String attachmentId)`

### Parameters
#### Path Parameters
- **emailId** (String) - Required - The ID of the email.
- **attachmentId** (String) - Required - The ID of the attachment.
```

--------------------------------

### Get HTTP Response Body

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Retrieves the body of an HTTP response, typically parsed into a specific type.

```java
public T getBody()
```

--------------------------------

### Typical Usage Pattern for Sending Email

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Demonstrates the typical usage pattern for initializing the Resend client and sending a single email. Includes error handling for potential exceptions.

```java
// Initialize the client with API key
Resend resend = new Resend(System.getenv("RESEND_API_KEY"));

// Send a single email
CreateEmailOptions emailOptions = CreateEmailOptions.builder()
    .from("sender@example.com")
    .to("recipient@example.com")
    .subject("Hello World")
    .text("This is a test email")
    .build();

try {
    CreateEmailResponse response = resend.emails().send(emailOptions);
    System.out.println("Email sent with ID: " + response.getId());
} catch (ResendException e) {
    System.err.println("Failed to send email: " + e.getMessage());
    System.err.println("Status code: " + e.getStatusCode());
}

```

--------------------------------

### Initialize Resend Client with API Key from Secrets Manager

Source: https://github.com/resend/resend-java/blob/main/_autodocs/configuration.md

Shows how to initialize the Resend client by fetching the API key from a secrets management service.

```java
// ✓ GOOD: Use secrets manager
Resend resend = new Resend(secretsManager.get("resend.api_key"));
```

--------------------------------

### Get Audiences Service (Deprecated)

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Returns an Audiences object for audience operations. This method is deprecated and `segments()` should be used instead.

```java
@Deprecated
public Audiences audiences()

```

--------------------------------

### ResendMapper writeValue Example

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Serializes a Java object into a JSON string using the ResendMapper. This is useful for preparing request bodies.

```java
CreateEmailOptions options = CreateEmailOptions.builder().build();
String json = mapper.writeValue(options);
// Result: {"from":"...", "to":[...], ...}
```

--------------------------------

### Initialize Client

Source: https://github.com/resend/resend-java/blob/main/_autodocs/README.md

Initializes the Resend client using an API key from environment variables. This is the main entry point for interacting with the Resend API.

```APIDOC
## Initialize Client

### Description
Initializes the Resend client using an API key from environment variables. This is the main entry point for interacting with the Resend API.

### Method
```java
Resend resend = new Resend(System.getenv("RESEND_API_KEY"));
```

### Parameters
- **RESEND_API_KEY** (string) - Required - Your Resend API key, typically set as an environment variable.
```

--------------------------------

### Initialize Resend Client with Environment Variable

Source: https://github.com/resend/resend-java/blob/main/_autodocs/configuration.md

Configure the Resend client using the RESEND_API_KEY environment variable for secure API key management. This avoids hardcoding sensitive credentials.

```java
Resend resend = new Resend(System.getenv("RESEND_API_KEY"));
```

```bash
# Linux/macOS
export RESEND_API_KEY=re_1234567890abcdef
```

```powershell
# Windows (PowerShell)
$env:RESEND_API_KEY = "re_1234567890abcdef"
```

```properties
RESEND_API_KEY=re_1234567890abcdef
```

--------------------------------

### List all email templates

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Retrieves all email templates associated with the account. This method can be used without any parameters to get an unfiltered list.

```java
ListTemplatesResponseSuccess response = resend.templates().list();
for (Template template : response.getData()) {
    System.out.println(template.getId() + ": " + template.getName());
}
```

--------------------------------

### Get Automations Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Returns an Automations object for managing email automation workflows. Use this service to create and manage automations.

```java
public Automations automations()

```

--------------------------------

### Project Directory Structure

Source: https://github.com/resend/resend-java/blob/main/_autodocs/MANIFEST.md

Illustrates the hierarchical organization of the Resend Java client library documentation files.

```text
output/
├── README.md (START HERE)
├── INDEX.md (Navigation)
├── MANIFEST.md (This file)
├── types.md (All type definitions)
├── configuration.md (Setup and configuration)
├── errors.md (Error handling)
└── api-reference/
    ├── resend-client.md (Main entry point)
    ├── emails-service.md (Email operations)
    ├── batch-service.md (Batch email send)
    ├── contacts-service.md (Contact management)
    ├── domains-service.md (Domain management)
    ├── templates-service.md (Template management)
    ├── apikeys-service.md (API key management)
    └── core-utilities.md (Infrastructure classes)
```

--------------------------------

### Get Events Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Returns an Events object for querying email events. Use this service to access email event data.

```java
public Events events()

```

--------------------------------

### Initialize Resend Client with API Key

Source: https://github.com/resend/resend-java/blob/main/_autodocs/configuration.md

Initialize the Resend client by passing your API key directly to the constructor. Ensure the API key is obtained from your Resend Dashboard.

```java
Resend resend = new Resend("your_api_key_here");
```

--------------------------------

### Get Logs Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Returns a Logs object for querying email activity logs. Use this service to retrieve log data.

```java
public Logs logs()

```

--------------------------------

### Initialize Batch Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/batch-service.md

Instantiate the Batch service with your Resend API key.

```java
public Batch(String apiKey)
```

--------------------------------

### Error Handling

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/domains-service.md

Provides examples of how to handle potential `ResendException` errors when interacting with the Domains API, including specific status codes.

```APIDOC
## Error Handling

```java
try {
    resend.domains().verify("domain_123");
} catch (ResendException e) {
    if (e.getStatusCode() == 404) {
        System.err.println("Domain not found");
    } else if (e.getStatusCode() == 400) {
        System.err.println("Invalid domain or verification failed: " + e.getMessage());
    } else {
        System.err.println("Error: " + e.getMessage());
    }
}
```
```

--------------------------------

### Initialize Contacts Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/contacts-service.md

Instantiate the Contacts service with your API key. This is the entry point for all contacts-related operations.

```java
public Contacts(String apiKey)
```

--------------------------------

### Access Topics Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Get a `Topics` service object for managing email topics, which are used for subscription management. This is for controlling email subscriptions.

```java
CreateTopicResponseSuccess topic = resend.topics().create(options);
```

--------------------------------

### Access Broadcasts Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Get a `Broadcasts` service object for sending broadcast emails to specific contact segments. This is for one-to-many email campaigns.

```java
CreateBroadcastResponseSuccess broadcast = resend.broadcasts().create(options);
```

--------------------------------

### Create and Verify a Domain

Source: https://github.com/resend/resend-java/blob/main/_autodocs/README.md

Programmatically create a new sending domain and then verify its status. This involves creating the domain first and then calling the verify method.

```java
// Create domain
CreateDomainResponse response = resend.domains().create(
    new CreateDomainOptions("mail.example.com")
);

// Wait for DNS configuration...

// Verify domain
VerifyDomainResponse verified = resend.domains().verify(response.getId());
System.out.println("Status: " + verified.getStatus());
```

--------------------------------

### Access Contact Properties Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Get a `ContactProperties` service instance to manage custom properties for your contacts. This is useful for advanced contact segmentation.

```java
ContactProperties service = resend.contactProperties();
```

--------------------------------

### ResendMapper readValue Example

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Deserializes a JSON string into a Java object of a specified type using the ResendMapper. This is useful for parsing API responses.

```java
String json = "{\"id\":\"email_123\"}";
CreateEmailResponse response = mapper.readValue(json, CreateEmailResponse.class);
```

--------------------------------

### Create Batch Emails (Alias)

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/batch-service.md

Use the `create` method as an alias for `send()` to create and send a batch of emails. It functions identically to the basic `send` method.

```java
public CreateBatchEmailsResponse create(List<CreateEmailOptions> emails) throws ResendException
```

```java
CreateBatchEmailsResponse response = resend.batch().create(emailList);
```

--------------------------------

### CreateTemplateOptions Configuration

Source: https://github.com/resend/resend-java/blob/main/_autodocs/types.md

Defines the configuration options for creating a new template, including name, subject, HTML and text parts, and an optional alias. Required fields are name and subject.

```java
public class CreateTemplateOptions {
    private String name;
    private String subject;
    private String htmlPart;
    private String textPart;
    private String alias;
}
```

--------------------------------

### get(String contactIdOrEmail)

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/contacts-service.md

Retrieves a global contact by their unique ID or email address. This method is useful for fetching the complete details of a specific contact.

```APIDOC
## get(String contactIdOrEmail)

### Description
Retrieves a global contact by ID or email address. This method is useful for fetching the complete details of a specific contact.

### Method
```java
public GetContactResponseSuccess get(String contactIdOrEmail) throws ResendException
```

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Parameters Table
| Parameter | Type | Required | Default | Description |
|---|---|---|---|---|
| contactIdOrEmail | String | Yes | — | Contact ID or email address |

### Returns
`GetContactResponseSuccess` — Complete contact details

### Throws
`ResendException` — If contact not found or retrieval fails

### Example
```java
GetContactResponseSuccess contact = resend.contacts().get("john@example.com");
System.out.println("Name: " + contact.getFirstName() + " " + contact.getLastName());

// Or by ID
GetContactResponseSuccess contact = resend.contacts().get("contact_123");
```
```

--------------------------------

### list() - List All Templates

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Retrieves all templates for the account, with support for pagination.

```APIDOC
## list() - List All Templates

Retrieves all templates for the account with pagination support.

### Method
GET

### Endpoint
/templates

### Parameters
#### Query Parameters
- **limit** (Integer) - Optional - The maximum number of templates to return.
- **after** (String) - Optional - The cursor for the next page of results.

### Response
#### Success Response (200)
- **data** (Array) - A list of template objects.
  - **id** (String) - The unique identifier of the template.
  - **name** (String) - The name of the template.
  - **subject** (String) - The subject of the template.
  - **html_part** (String) - The HTML content of the template.
  - **text_part** (String) - The plain text content of the template.
  - **variables** (Object) - An object containing template variables.
  - **alias** (String) - An optional alias for the template.
  - **created_at** (String) - The timestamp when the template was created.
  - **updated_at** (String) - The timestamp when the template was last updated.
- **next_cursor** (String) - The cursor for the next page of results.

### Response Example
```json
{
  "data": [
    {
      "id": "tmpl_abc123",
      "name": "Welcome Email",
      "subject": "Welcome {{first_name}}!",
      "html_part": "<h1>Hello {{first_name}}</h1><p>Welcome to our service!</p>",
      "text_part": "Hello {{first_name}}!\nWelcome to our service!",
      "variables": {},
      "alias": "welcome-email",
      "created_at": "2023-10-27T10:00:00Z",
      "updated_at": "2023-10-27T10:05:00Z"
    }
  ],
  "next_cursor": "cursor_456"
}
```
```

--------------------------------

### list() - List All API Keys

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/apikeys-service.md

Retrieves all API keys for the account, with support for pagination.

```APIDOC
## list() - List All API Keys

### Description
Retrieves all API keys for the account, with support for pagination.

### Method
GET

### Endpoint
/v1/api-keys

### Parameters
#### Query Parameters
- **limit** (integer) - Optional - The maximum number of API keys to return.
- **after** (string) - Optional - The ID of the API key to start listing after.
- **before** (string) - Optional - The ID of the API key to list before.

### Response
#### Success Response (200)
- **keys** (array of objects) - A list of API key metadata. Each object contains:
  - **id** (string) - The unique identifier of the API key.
  - **name** (string) - The name of the API key.
  - **status** (string) - The status of the API key (e.g., "active", "revoked").
  - **created_at** (string) - The timestamp when the API key was created.

### Response Example
```json
{
  "keys": [
    {
      "id": "key_abc123",
      "name": "Production API Key",
      "status": "active",
      "created_at": "2023-10-26T10:00:00Z"
    },
    {
      "id": "key_def456",
      "name": "Test API Key",
      "status": "active",
      "created_at": "2023-10-25T09:00:00Z"
    }
  ]
}
```
```

--------------------------------

### Get Contact Topics Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/contacts-service.md

Obtain the ContactTopics service for managing contact subscriptions to topics. This service allows for listing topic subscriptions for a given contact.

```java
ContactTopics topicsService = resend.contacts().topics();
ListContactTopicsResponse topics = topicsService.list("contact_id");
```

--------------------------------

### Get Contact Segments Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/contacts-service.md

Retrieve the ContactSegments service to manage contact memberships within segments. Use this to add or remove contacts from specific segments.

```java
ContactSegments segmentsService = resend.contacts().segments();
AddContactToSegmentResponseSuccess result = segmentsService.add(options);
```

--------------------------------

### create() - Create API Key

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/apikeys-service.md

Creates a new API key with optional permissions and expiration. The API key token is only shown once at creation and should be stored securely.

```APIDOC
## create() - Create API Key

### Description
Creates a new API key with optional permissions and expiration.

### Method
POST

### Endpoint
/v1/api-keys

### Parameters
#### Request Body
- **name** (string) - Required - The name of the API key.
- **permissions** (array of strings) - Optional - The permissions to grant to the API key. Possible values: "sending", "sending:write", "emails:read", "emails:write", "contacts:read", "contacts:write", "batch:read", "batch:write", "uploads:read", "uploads:write".
- **domain_id** (string) - Optional - The ID of the domain to associate with the API key.
- **expires_in** (string) - Optional - The expiration time for the API key (e.g., "24h", "7d").

### Response
#### Success Response (200)
- **id** (string) - The unique identifier of the API key.
- **token** (string) - The generated API key token. This is only shown once.

### Request Example
```json
{
  "name": "Production API Key",
  "permissions": ["sending", "contacts:read"],
  "expires_in": "7d"
}
```

### Response Example
```json
{
  "id": "key_abc123",
  "token": "re ซึ่งเป็นคีย์ลับที่สร้างขึ้นใหม่"
}
```
```

--------------------------------

### Domain Verification Workflow

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/domains-service.md

Illustrates the typical workflow for setting up and verifying a domain with Resend, including creating a domain, configuring DNS records, and verifying the domain.

```APIDOC
## Domain Verification Workflow

Typical workflow for setting up a domain:

```java
// Step 1: Create the domain
CreateDomainOptions createOptions = new CreateDomainOptions();
createOptions.setDomain("mail.mycompany.com");
CreateDomainResponse createResponse = resend.domains().create(createOptions);

// Step 2: Get DNS records and configure them in your DNS provider
Domain domain = resend.domains().get(createResponse.getId());
System.out.println("Add these DNS records to your DNS provider:");
for (DnsRecord record : domain.getDnsRecords()) {
    System.out.println("Type: " + record.getType());
    System.out.println("Name: " + record.getName());
    System.out.println("Value: " + record.getValue());
}

// Step 3: After DNS propagation (typically 15-30 minutes), verify
Thread.sleep(5 * 60 * 1000); // Wait 5 minutes
VerifyDomainResponse verifyResponse = resend.domains().verify(domain.getId());

if ("success".equals(verifyResponse.getStatus())) {
    System.out.println("Domain verified successfully!");
} else {
    System.out.println("Domain verification still pending: " + verifyResponse.getStatus());
}
```
```

--------------------------------

### CreateApiKeyOptions

Source: https://github.com/resend/resend-java/blob/main/_autodocs/types.md

Configuration for creating API keys, including a display name and optional permission scopes.

```APIDOC
## CreateApiKeyOptions

### Description
Configuration for creating API keys, including a display name and optional permission scopes.

### Fields
#### name (String) - Yes - Display name for the key
#### permissions (List<String>) - No - Permission scopes
```

--------------------------------

### Access Batch Email Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/resend-client.md

Get a `Batch` service instance for sending multiple emails efficiently in a single request. Supports up to 100 emails per batch.

```java
List<CreateEmailOptions> emails = Arrays.asList(email1, email2, email3);
CreateBatchEmailsResponse response = resend.batch().send(emails);
```

--------------------------------

### Initialize Emails Service

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/emails-service.md

Instantiate the Emails service with your Resend API key.

```java
public Emails(String apiKey)
```

--------------------------------

### Template Versioning Operations

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Demonstrates how to interact with template versions using the Resend Java SDK. This includes fetching the current template, creating a new version by duplicating an existing one, updating the new version's content, and publishing it.

```APIDOC
## Template Versioning

Templates are versioned automatically.

### Get current template
```java
GetTemplateResponseSuccess template = resend.templates().get("tmpl_123");
System.out.println("Version: " + template.getVersion());
```

### Create a new version by duplicating
```java
DuplicateTemplateResponseSuccess copy = resend.templates().duplicate("tmpl_123");
System.out.println("New version created: " + copy.getId());
```

### Update the copy
```java
UpdateTemplateOptions options = new UpdateTemplateOptions();
options.setHtmlPart("<h1>New Version Content</h1>");
resend.templates().update(copy.getId(), options);
```

### Publish when ready
```java
resend.templates().publish(copy.getId());
```
```

--------------------------------

### Use Builder Pattern for Email Options

Source: https://github.com/resend/resend-java/blob/main/_autodocs/README.md

Construct `CreateEmailOptions` using the builder pattern for clear, chainable, and validated option configurations.

```java
// ✓ Good: Clear, chainable, validates on build
CreateEmailOptions options = CreateEmailOptions.builder()
    .from("sender@example.com")
    .to("recipient@example.com")
    .subject("Hello")
    .text("Body")
    .build();
```

--------------------------------

### Handle API Key Creation Errors

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/apikeys-service.md

Demonstrates how to catch and handle specific `ResendException` errors that may occur during the API key creation process. This includes handling invalid options, authentication failures, and rate limiting.

```java
try {
    CreateApiKeyResponse response = resend.apiKeys().create(options);
} catch (ResendException e) {
    if (e.getStatusCode() == 400) {
        System.err.println("Invalid key options: " + e.getMessage());
    } else if (e.getStatusCode() == 401) {
        System.err.println("Authentication failed");
    } else if (e.getStatusCode() == 429) {
        System.err.println("Rate limited - too many keys created recently");
    }
}
```

--------------------------------

### Verify a Domain's DNS Configuration

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/domains-service.md

Initiate domain verification by checking if the necessary DNS records have been correctly configured. This confirms your domain is ready for sending.

```java
VerifyDomainResponse response = resend.domains().verify("domain_123");
System.out.println("Verification status: " + response.getStatus());
```

--------------------------------

### List API Keys with Pagination

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/apikeys-service.md

Retrieves API keys with pagination support using limit, after, and before parameters.

```java
ListParams params = ListParams.builder()
    .limit(20)
    .after("cursor_123")
    .build();

ListApiKeysResponse response = resend.apiKeys().list(params);
System.out.println("Retrieved " + response.getKeys().size() + " API keys");
```

--------------------------------

### Avoid Hardcoding API Key

Source: https://github.com/resend/resend-java/blob/main/_autodocs/configuration.md

Illustrates insecure methods of initializing the Resend client by hardcoding the API key directly in the source code or committing it to version control.

```java
// ✗ BAD: Hardcode in source
Resend resend = new Resend("re_actual_key_12345");

// ✗ BAD: Check into version control
// .env file with RESEND_API_KEY=re_12345
```

--------------------------------

### BaseService getHttpClient Method

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Retrieves the configured HTTP client instance from the BaseService.

```java
public IHttpClient getHttpClient()
```

--------------------------------

### Handle Template Creation Errors

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/templates-service.md

Shows how to implement error handling for template creation using a try-catch block to manage specific Resend API exceptions like invalid input, not found, or name conflicts.

```java
try {
    CreateTemplateResponseSuccess template = resend.templates().create(options);
} catch (ResendException e) {
    if (e.getStatusCode() == 400) {
        System.err.println("Invalid template: " + e.getMessage());
    } else if (e.getStatusCode() == 404) {
        System.err.println("Template not found");
    } else if (e.getStatusCode() == 409) {
        System.err.println("Name already exists");
    }
}
```

--------------------------------

### List API Keys by Permissions

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/apikeys-service.md

Retrieves a list of API keys and filters them to display keys with 'write' permissions. Ensure you have initialized the Resend client.

```java
ListApiKeysResponse response = resend.apiKeys().list();

System.out.println("Keys with write access:");
for (ApiKey key : response.getKeys()) {
    List<String> permissions = key.getPermissions();
    if (permissions != null && permissions.stream()
            .anyMatch(p -> p.contains("write"))) {
        System.out.println("  - " + key.getName());
    }
}
```

--------------------------------

### Use Templates

Source: https://github.com/resend/resend-java/blob/main/_autodocs/README.md

Sends an email using a pre-defined template, allowing for dynamic content injection via variables.

```APIDOC
## Use Templates

### Description
Sends an email using a pre-defined template, allowing for dynamic content injection via variables.

### Method
```java
CreateEmailResponse response = resend.emails().send(options);
```

### Parameters
#### Request Body (`CreateEmailOptions`)
- **from** (string) - Required - The sender's email address.
- **to** (string) - Required - The recipient's email address.
- **template** (Template object) - Required - The template to use.
  - **id** (string) - Required - The ID of the template.
  - **variables** (Map<string, object>) - Optional - Key-value pairs for dynamic content.

### Request Example
```java
Template template = Template.builder()
    .id("tmpl_welcome_123")
    .addVariable("first_name", "John")
    .addVariable("company", "ACME Corp")
    .build();

CreateEmailOptions options = CreateEmailOptions.builder()
    .from("sender@example.com")
    .to("john@example.com")
    .template(template)
    .build();
```

### Response
#### Success Response
- **id** (string) - The unique identifier for the sent email.
```

--------------------------------

### IHttpClient.perform (basic)

Source: https://github.com/resend/resend-java/blob/main/_autodocs/api-reference/core-utilities.md

Performs an HTTP request with the specified details. This is a core method for SDK communication.

```APIDOC
## IHttpClient.perform (basic)

### Description
Performs an HTTP request with the specified details.

### Method
`public AbstractHttpResponse<String> perform(
    String path,
    String apiKey,
    HttpMethod method,
    String payload,
    MediaType mediaType
)`

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
- **path** (`String`) - Required - The API endpoint path.
- **apiKey** (`String`) - Required - The API key for authentication.
- **method** (`HttpMethod`) - Required - The HTTP method (GET, POST, etc.).
- **payload** (`String`) - Optional - The request body payload.
- **mediaType** (`MediaType`) - Required - The media type of the payload.
```