Error Handling - Law4Devs

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

​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