Custom Exceptions in Dart

Custom exceptions in Dart allow developers to create specific error types tailored to their application's needs. They enhance error handling and improve code readability.

Creating Custom Exceptions

To create a custom exception in Dart, you need to extend the built-in Exception class. Here's a simple example:

class InsufficientFundsException implements Exception {
  final String message;

  InsufficientFundsException(this.message);

  @override
  String toString() => 'InsufficientFundsException: $message';
}
    

This custom exception can be used to handle specific scenarios in financial applications.

Using Custom Exceptions

Once defined, you can throw and catch custom exceptions just like built-in exceptions. Here's how:

void withdrawMoney(double amount) {
  if (amount > balance) {
    throw InsufficientFundsException('Not enough balance to withdraw $amount');
  }
  // Proceed with withdrawal
}

try {
  withdrawMoney(1000);
} on InsufficientFundsException catch (e) {
  print(e.message);
} catch (e) {
  print('An unexpected error occurred: $e');
}
    

Best Practices

• Use descriptive names for custom exceptions
• Include relevant information in the exception message
• Consider implementing a toString() method for better error reporting
• Use custom exceptions to differentiate between various error conditions in your code

Benefits of Custom Exceptions

Custom exceptions offer several advantages:

1. Improved code readability
2. More precise error handling
3. Better documentation of possible failure modes
4. Enhanced debugging capabilities

By using custom exceptions, you can create more robust and maintainable Dart applications.

Related Concepts

To further enhance your understanding of error handling in Dart, explore these related topics:

• Dart Exceptions
• Dart Try-Catch Blocks
• Dart Throw Keyword

Custom exceptions are a powerful tool in Dart programming. They allow you to create more expressive and maintainable code by providing specific error types for different scenarios in your application.