Oracle Java SE 21 Developer Professional : 1z1-830

Exam Code: 1z1-830
Exam Name: Java SE 21 Developer Professional
Updated: Sep 30, 2026
Q & A: 85 Questions and Answers

About Oracle 1z1-830 Exam Questions

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Oracle 1z1-830 Exam Syllabus Topics:

Section	Weight	Objectives
Advanced Features and Annotations	3%	- Annotations, built-in annotations, custom annotations - Generics, type parameters, wildcards, type erasure
Java I/O and Localization	5%	- Resource bundles, locale, formatting messages, numbers, dates - File I/O, NIO.2, streams, readers/writers, serialization
Functional Programming and Streams	15%	- Lambda expressions, functional interfaces, method references - Stream API: create, intermediate/terminal operations, parallel streams, grouping, partitioning - Optional class, primitive streams
Handling Date, Time, Text, Numeric and Boolean Values	12%	- Use primitives and wrapper classes, evaluate expressions and apply type conversions - Use Date-Time API: LocalDate, LocalTime, LocalDateTime, Period, Duration, Instant, ZonedDateTime - Manipulate text, text blocks, String, StringBuilder and StringBuffer
Modules and Packaging	5%	- Create and use JAR files, modular and non-modular builds - Module system: module-info.java, exports, requires, provides, uses
Working with Arrays and Collections	12%	- Declare, instantiate, initialize, use arrays and multidimensional arrays - Collections Framework: List, Set, Map, Deque, Queue, sorting, searching
Concurrency and Multithreading	10%	- Synchronization, locks, concurrent collections, thread safety - Thread lifecycle, Runnable, Callable, ExecutorService, virtual threads
Controlling Program Flow	10%	- Loops: for, enhanced for, while, do-while, break, continue, return - Decision constructs: if-else, switch expressions and statements, pattern matching
Using Object-Oriented Concepts	20%	- Overloading, overriding, Object class methods, immutable objects - Classes, records, objects, constructors, initializers, methods, fields, encapsulation - Inheritance, abstract classes, sealed classes, interfaces, polymorphism - Enums, nested classes, local variable type inference
Handling Exceptions	8%	- Create and use custom exceptions, throw, throws - Exception hierarchy, try-catch-finally, multi-catch, try-with-resources

Oracle Java SE 21 Developer Professional Sample Questions:

Question #1

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?

A. It prints "Task is complete" once and throws an exception.
B. It prints "Task is complete" twice and throws an exception.
C. It exits normally without printing anything to the console.
D. It prints "Task is complete" twice, then exits normally.
E. It prints "Task is complete" once, then exits normally.

Reveal Solution Discussion 0

Correct Answer: A 🗳️