Error Handling

What is Error Handling?

Error handling is the process of anticipating, detecting, and responding to runtime anomalies in software. Proper handling improves reliability, usability, and maintainability.

General Best Practices

• Prefer exceptions over error codes where the language supports them.
• Never swallow errors silently; log them with context.
• Provide user-friendly messages without exposing internal details.
• Use specific exception types to differentiate error conditions.
• Clean up resources (files, connections) in finally blocks or using scoped constructs.

JavaScript

Use try...catch for synchronous code and .catch() or async/await for promises.

// Synchronous example
function parseJSON(str) {
    try {
        return JSON.parse(str);
    } catch (e) {
        console.error('Invalid JSON:', e);
        return null;
    }
}

// Asynchronous example
async function fetchData(url) {
    try {
        const res = await fetch(url);
        if (!res.ok) throw new Error(`HTTP ${res.status}`);
        return await res.json();
    } catch (err) {
        console.error('Fetch error:', err);
        throw err; // rethrow for callers
    }
}
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Python

Use try...except blocks and the finally clause for cleanup.

def read_file(path):
    try:
        with open(path, 'r') as f:
            return f.read()
    except FileNotFoundError as e:
        print(f"File not found: {e}")
        return None
    except Exception as e:
        print(f"Unexpected error: {e}")
        raise
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Java

Use try...catch with specific exception types and try-with-resources for automatic resource management.

public String readFile(String path) {
    try (BufferedReader br = new BufferedReader(new FileReader(path))) {
        return br.lines().collect(Collectors.joining("\n"));
    } catch (FileNotFoundException e) {
        System.err.println("File not found: " + e.getMessage());
        return null;
    } catch (IOException e) {
        System.err.println("I/O error: " + e.getMessage());
        throw new RuntimeException(e);
    }
}
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