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[VV123] The Java 21 Newsletter: Certification's exceptions

August 4, 2025

Here's a clean and focused Java Exception Tree containing only the exceptions relevant to the Java certifications (like 1Z0-819, 1Z0-830), with a clear emphasis on:

  • โœ… Runtime vs checked
  • โœ… Certification usage context
  • โœ… Avoiding noise from obscure exceptions

๐Ÿง  What to Know for Each (Certification-Relevant Exceptions)

  1. ๐Ÿ“„ IOException โ€“ Checked: File or stream operations, often used in try-with-resources.
  2. ๐Ÿ“ FileNotFoundException โ€“ Checked: Thrown when attempting to open a non-existent file.
  3. ๐Ÿ“ค EOFException โ€“ Checked: End of stream reached unexpectedly during input.
  4. ๐Ÿ“ฆ UncheckedIOException โ€“ Unchecked: Wraps IOException in functional interfaces or streams.
  5. ๐Ÿ’ค InterruptedException โ€“ Checked: Thrown when a thread is interrupted (e.g., during Thread.sleep()).
  6. โฑ๏ธ TimeoutException โ€“ Checked: Occurs when waiting too long for a task to complete (e.g., Future.get() with timeout).
  7. ๐Ÿ’ฅ ExecutionException โ€“ Checked: Wraps exceptions thrown in async tasks (e.g., from Future).
  8. ๐Ÿ” InvocationTargetException โ€“ Checked: Thrown when a reflected method throws an exception.
  9. ๐Ÿ” IllegalAccessException โ€“ Checked: Reflection access to a field/method is illegal.
  10. ๐Ÿงฑ InstantiationException โ€“ Checked: Attempt to instantiate an abstract class or interface via reflection.
  11. ๐Ÿงญ NoSuchMethodException โ€“ Checked: Requested method does not exist (common in reflection).
  12. ๐ŸŒ MissingResourceException โ€“ Unchecked: Missing key in a ResourceBundle.
  13. โž— ArithmeticException โ€“ Unchecked: Arithmetic error, like division by zero.
  14. โŒ NullPointerException โ€“ Unchecked: Dereferencing a null reference.
  15. ๐Ÿ“‰ IndexOutOfBoundsException โ€“ Unchecked: General out-of-bounds for collections/arrays.
  16. ๐Ÿงฎ ArrayIndexOutOfBoundsException โ€“ Unchecked: Specifically for arrays.
  17. โœ‚๏ธ StringIndexOutOfBoundsException โ€“ Unchecked: Specifically for strings.
  18. ๐Ÿงช IllegalArgumentException โ€“ Unchecked: Invalid method parameter passed.
  19. ๐Ÿ”ข NumberFormatException โ€“ Unchecked: Failed conversion from string to number (e.g., "abc" to int).
  20. ๐ŸŒ€ IllegalStateException โ€“ Unchecked: Method invoked at an inappropriate time (e.g., reusing a closed stream).
  21. ๐Ÿ”„ ClassCastException โ€“ Unchecked: Invalid casting between incompatible types.
  22. ๐Ÿšซ UnsupportedOperationException โ€“ Unchecked: Operation not supported, such as on unmodifiable collections.
  23. ๐Ÿ” ConcurrentModificationException โ€“ Unchecked: Modifying a collection during iteration.
  24. ๐Ÿ“ InputMismatchException โ€“ Unchecked: Scanner receives input of unexpected type.
  25. ๐Ÿ“ญ NoSuchElementException โ€“ Unchecked: Accessing elements from an exhausted iterator or empty optional/stream.
  26. ๐Ÿ›ก๏ธ SecurityException โ€“ Unchecked: Access control violation (e.g., attempting a restricted operation).