5 · Intermediate · lesson 25 of 41

Exceptions & try-with-resources

Handling failure without cluttering happy paths.

Java

try (var reader = Files.newBufferedReader(path)) {
    return reader.readLine();
} catch (NoSuchFileException e) {
    return "";
} catch (IOException e) {
    throw new RuntimeException("read failed", e);
}

// Custom exception
class NotFoundException extends RuntimeException {
    public NotFoundException(String msg) { super(msg); }
}

▸Checked exceptions (extends Exception) must be caught or declared.
▸Unchecked (extends RuntimeException) don't require a throws clause.
▸try-with-resources closes AutoCloseable resources in reverse order.

Key takeaways

✓Catch narrow types first, wide types last.
✓Always close I/O — let the compiler do it via try-with-resources.

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