Error Handling

Exception Hierarchy

All SDK exceptions extend eu.law4devs.sdk.exceptions.Law4DevsException, which itself extends RuntimeException.

RuntimeException
└── Law4DevsException          base — any SDK error
    ├── NotFoundError          404 — resource not found
    ├── ValidationError        400 — invalid parameters
    ├── RateLimitError         429 — rate limit exceeded
    └── ServerError            5xx — server-side error

Every exception exposes a getStatusCode() method:

try {
    Article article = client.articles().get("gdpr", 9999);
} catch (NotFoundError e) {
    System.out.println("Not found: " + e.getMessage());  // message from API
    System.out.println("Status: " + e.getStatusCode());  // 404
}

Catching Specific Errors

import eu.law4devs.sdk.exceptions.Law4DevsException;
import eu.law4devs.sdk.exceptions.NotFoundError;
import eu.law4devs.sdk.exceptions.RateLimitError;
import eu.law4devs.sdk.exceptions.ValidationError;

try {
    var page = client.articles().list("invalid-framework");
} catch (NotFoundError e) {
    // Framework not found
    System.out.println("Framework not found: " + e.getMessage());
} catch (ValidationError e) {
    // Bad request parameters
    System.out.println("Invalid request: " + e.getMessage());
} catch (RateLimitError e) {
    // Retry after a delay (SDK already retried 3 times)
    System.out.println("Rate limit hit: " + e.getMessage());
} catch (Law4DevsException e) {
    // All other SDK errors (server errors, network failures)
    System.out.println("SDK error (" + e.getStatusCode() + "): " + e.getMessage());
}

Automatic Retry

The SDK automatically retries on 429 Too Many Requests and 5xx Server Error responses using exponential backoff:

Attempt	Wait
1st retry	1 second
2nd retry	2 seconds
3rd retry	4 seconds

After maxRetries (default 3) attempts, the exception is re-thrown. To disable retries, set maxRetries(0):

Law4DevsClient client = Law4DevsClient.builder()
    .apiKey(System.getenv("LAW4DEVS_API_KEY"))
    .maxRetries(0)
    .build();

NotFoundError (404) and ValidationError (400) are never retried — they represent client errors that will not resolve by retrying.

Network Errors

Connection failures (timeout, DNS, SSL) throw Law4DevsException with a message describing the failure:

import eu.law4devs.sdk.exceptions.Law4DevsException;

try {
    var page = client.frameworks().list();
} catch (Law4DevsException e) {
    System.out.println("SDK error: " + e.getMessage());
}

Errors in `iter()` Loops

Exceptions can be thrown mid-iteration if a page request fails. Wrap iter() loops in a try/catch:

try {
    for (ArticleSummary a : client.articles().iter("gdpr")) {
        System.out.println(a.title());
    }
} catch (Law4DevsException e) {
    System.out.println("Error mid-iteration: " + e.getMessage());
}

Best Practices

Always catch Law4DevsException as a fallback to handle unexpected errors
Wrap iter() loops in a try/catch — exceptions can occur mid-iteration if a page request fails
Use getStatusCode() to distinguish error types when handling Law4DevsException generically
For batch processing, implement a retry strategy at the application level if you need finer control than the built-in retry
Prefer specific exception types (NotFoundError, RateLimitError) over the base class for cleaner error handling

Overview

Python SDK

TypeScript SDK

PHP SDK

Java SDK

Flutter SDK

Rust SDK

Exception Hierarchy

Catching Specific Errors

Automatic Retry

Network Errors

Errors in `iter()` Loops

Best Practices

​Exception Hierarchy

​Catching Specific Errors

​Automatic Retry

​Network Errors

​Errors in iter() Loops

​Best Practices

Exception Hierarchy

Catching Specific Errors

Automatic Retry

Network Errors

Errors in `iter()` Loops

Best Practices