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Free 1Z0-830 Mock Exam – Practice Online Confidently

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Exam Code: 1Z0-830
Exam Questions: 84
Java SE 21 Developer Professional
Updated: 25 Nov, 2025
Question 1

Which three of the following are correct about the Java module system? 

Options :
Answer: B,C,F

Question 2

Which StringBuilder variable fails to compile? java public class StringBuilderInstantiations { public static void main(String[] args) { var stringBuilder1 = new StringBuilder(); var stringBuilder2 = new StringBuilder(10); var stringBuilder3 = new StringBuilder("Java"); var stringBuilder4 = new StringBuilder(new char[]{'J', 'a', 'v', 'a'}); } } 

Options :
Answer: B

Question 3

Given: java double amount = 42_000.00; NumberFormat format = NumberFormat.getCompactNumberInstance(Locale.FRANCE, NumberFormat.Style. SHORT); System.out.println(format.format(amount)); What is the output?

Options :
Answer: D

Question 4

Given: java ExecutorService service = Executors.newFixedThreadPool(2); Runnable task = () -> System.out.println("Task is complete"); service.submit(task); service.shutdown(); service.submit(task); What happens when executing the given code fragment? 

Options :
Answer: A

Question 5

Which methods compile? 

Options :
Answer: A,B

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