- A
try { int num = Integer.valueOf(input).intValue(); System.out.println(num); } catch (Exception e) { System.out.println("Invalid number"); }
Why wrong: Incorrect: Catching Exception is too broad; also valueOf throws NumberFormatException, but catching Exception is poor practice.
- B
int num = Integer.parseInt(input); System.out.println(num);
Why wrong: Incorrect: No exception handling; invalid input will cause an uncaught exception.
- C
if (input.matches("\\d+")) { int num = Integer.parseInt(input); System.out.println(num); } else { System.out.println("Invalid number"); }
Why wrong: Incorrect: Does not handle negative numbers or leading plus signs; also regex is less efficient.
- D
try { int num = Integer.parseInt(input); System.out.println(num); } catch (NumberFormatException e) { System.out.println("Invalid number"); }
Correct: Catches the specific exception and prints an error message.
Quick Answer
The correct choice is the try-catch block that uses `Integer.parseInt(input)` and catches `NumberFormatException` specifically, because this is the precise mechanism Java provides for integer parsing with NumberFormatException handling. When `parseInt` receives a non-numeric string, it throws a `NumberFormatException`, and the catch block gracefully intercepts that exception to print "Invalid number" instead of crashing the program. On the Oracle Certified Professional Java SE 17 Developer 1Z0-829 exam, this pattern tests your understanding of checked versus unchecked exceptions and the idiomatic use of try-catch for input validation—a common trap is catching a broader `Exception` type, which would mask other runtime issues like null pointers. Remember that `NumberFormatException` extends `IllegalArgumentException`, so it is an unchecked exception, meaning the compiler does not force you to handle it, but best practice demands you do when parsing user input. A useful memory tip: think "parse and catch the format fail"—the exception name itself tells you exactly what went wrong, so match your catch block to that specific type for clean, maintainable code.
1Z0-829 Practice Question: Handling Date, Time, Text, Numeric and Boolean Values
This 1Z0-829 practice question tests your understanding of handling date, time, text, numeric and boolean values. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A program reads user input as a string and needs to parse it into an integer, handling invalid input gracefully. Which code snippet correctly uses try-catch to parse and prints the result or 'Invalid number'?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
try { int num = Integer.parseInt(input); System.out.println(num); } catch (NumberFormatException e) { System.out.println("Invalid number"); }
Option D is correct because it uses `Integer.parseInt(input)` which throws a `NumberFormatException` for invalid input, and the catch block specifically catches that exception to print 'Invalid number'. This is the standard, idiomatic Java approach for parsing integers with error handling, as it directly addresses the requirement without unnecessary overhead or false positives.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
try { int num = Integer.valueOf(input).intValue(); System.out.println(num); } catch (Exception e) { System.out.println("Invalid number"); }
Why it's wrong here
Incorrect: Catching Exception is too broad; also valueOf throws NumberFormatException, but catching Exception is poor practice.
- ✗
int num = Integer.parseInt(input); System.out.println(num);
Why it's wrong here
Incorrect: No exception handling; invalid input will cause an uncaught exception.
- ✗
if (input.matches("\\d+")) { int num = Integer.parseInt(input); System.out.println(num); } else { System.out.println("Invalid number"); }
Why it's wrong here
Incorrect: Does not handle negative numbers or leading plus signs; also regex is less efficient.
- ✓
try { int num = Integer.parseInt(input); System.out.println(num); } catch (NumberFormatException e) { System.out.println("Invalid number"); }
Why this is correct
Correct: Catches the specific exception and prints an error message.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Option C (regex validation) thinking it's more efficient or 'cleaner', but they overlook that the regex `\d+` fails for negative numbers and other valid integer formats, while the try-catch approach in D is both correct and idiomatic for Java.
Detailed technical explanation
How to think about this question
Under the hood, `Integer.parseInt` uses a finite-state machine to parse the string character by character, checking for an optional sign and then digits, and throws `NumberFormatException` if any character is invalid or the string is empty. The `NumberFormatException` extends `IllegalArgumentException`, making it a runtime exception, so it does not require a try-catch but is typically caught for user input. In real-world applications, catching `NumberFormatException` is preferred over regex validation because it handles edge cases like locale-specific number formats or whitespace trimming automatically when combined with `trim()`.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 1Z0-829 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Questions learners often ask
What does this 1Z0-829 question test?
Handling Date, Time, Text, Numeric and Boolean Values — This question tests Handling Date, Time, Text, Numeric and Boolean Values — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: try { int num = Integer.parseInt(input); System.out.println(num); } catch (NumberFormatException e) { System.out.println("Invalid number"); } — Option D is correct because it uses `Integer.parseInt(input)` which throws a `NumberFormatException` for invalid input, and the catch block specifically catches that exception to print 'Invalid number'. This is the standard, idiomatic Java approach for parsing integers with error handling, as it directly addresses the requirement without unnecessary overhead or false positives.
What should I do if I get this 1Z0-829 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This 1Z0-829 practice question is part of Courseiva's free Oracle certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 1Z0-829 exam.
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