Oracle 1z1-830 Exam : Java SE 21 Developer Professional

Exam Code: 1z1-830
Exam Name: Java SE 21 Developer Professional
Updated: Sep 18, 2026
Q & A: 85 Questions and Answers

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Oracle 1z1-830 Exam Syllabus Topics:

Section	Objectives
Topic 1: Java I/O and NIO	- Use Path, Files, and related APIs - Process file system resources - Read and write files
Topic 2: Controlling Program Flow	- Apply decision statements and loops - Use switch expressions and pattern matching - Work with records and sealed classes
Topic 3: Java Concurrency	- Work with concurrent collections and executors - Create and manage threads - Use virtual threads
Topic 4: Collections and Generics	- Use sequenced collections and maps - Use List, Set, Map, Queue, and Deque implementations - Apply generics and bounded types
Topic 5: Modules and Packaging	- Package and deploy applications - Manage dependencies and exports - Create and use Java modules
Topic 6: Exception Handling	- Use try-with-resources - Create custom exceptions - Handle checked and unchecked exceptions
Topic 7: Handling Date, Time, Text, Numeric and Boolean Values	- Use date, time, duration, period, and localization APIs - Use String, StringBuilder, and related APIs - Work with primitive wrappers and number formatting
Topic 8: Object-Oriented Programming	- Apply inheritance and polymorphism - Create and use classes, interfaces, enums, and records - Implement encapsulation and abstraction
Topic 9: Functional Programming	- Use lambda expressions and method references - Process data using Stream API - Work with functional interfaces
Topic 10: Annotations and JDBC	- Connect to databases using JDBC - Use built-in and custom annotations - Execute SQL operations and process results

Oracle Java SE 21 Developer Professional Sample Questions:

Question #1

Given:
java
List<String> l1 = new ArrayList<>(List.of("a", "b"));
List<String> l2 = new ArrayList<>(Collections.singletonList("c"));
Collections.copy(l1, l2);
l2.set(0, "d");
System.out.println(l1);
What is the output of the given code fragment?

A. [d, b]
B. [a, b]
C. An UnsupportedOperationException is thrown
D. An IndexOutOfBoundsException is thrown
E. [d]
F. [c, b]

Reveal Solution Discussion 0

Correct Answer: F 🗳️