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Oracle 1z0-830 Exam Overview:
| Certification Vendor: | Oracle |
|---|---|
| Exam Name: | Java SE 21 Developer Professional |
| Exam Number: | 1Z0-830 |
| Exam Format: | Multiple Select, Multiple Choice |
| Certificate Validity Period: | 18 months |
| Exam Duration: | 120 minutes |
| Available Languages: | Chinese (Simplified), English, Japanese |
| Exam Price: | $300 USD |
| Passing Score: | 68% |
| Related Certifications: | Oracle Certified Professional: Java SE 11 Developer Oracle Certified Professional: Java SE 17 Developer |
| Real Exam Qty: | 50 |
| Recommended Training: | Oracle Java SE 21 Developer Training |
| Exam Registration: | Pearson VUE Oracle University Registration |
| Sample Questions: | Oracle 1z0-830 Sample Questions |
| Exam Way: | Online proctored or onsite at Pearson VUE test centers |
| Pre Condition: | No mandatory prerequisites; recommended 2+ years of Java development experience or equivalent knowledge |
| Official Syllabus URL: | https://education.oracle.com/java-se-21-developer/pexam_1Z0-830 |
Oracle 1z0-830 Exam Syllabus Topics:
| Section | Weight | Objectives |
|---|---|---|
| Topic 1: 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 |
| Topic 2: Controlling Program Flow | 10% | - Loops: for, enhanced for, while, do-while, break, continue, return - Decision constructs: if-else, switch expressions and statements, pattern matching |
| Topic 3: Java I/O and Localization | 5% | - Resource bundles, locale, formatting messages, numbers, dates - File I/O, NIO.2, streams, readers/writers, serialization |
| Topic 4: Handling Exceptions | 8% | - Create and use custom exceptions, throw, throws - Exception hierarchy, try-catch-finally, multi-catch, try-with-resources |
| Topic 5: Working with Arrays and Collections | 12% | - Declare, instantiate, initialize, use arrays and multidimensional arrays - Collections Framework: List, Set, Map, Deque, Queue, sorting, searching |
| Topic 6: Advanced Features and Annotations | 3% | - Annotations, built-in annotations, custom annotations - Generics, type parameters, wildcards, type erasure |
| Topic 7: Using Object-Oriented Concepts | 20% | - Classes, records, objects, constructors, initializers, methods, fields, encapsulation - Enums, nested classes, local variable type inference - Overloading, overriding, Object class methods, immutable objects - Inheritance, abstract classes, sealed classes, interfaces, polymorphism |
| Topic 8: Concurrency and Multithreading | 10% | - Synchronization, locks, concurrent collections, thread safety - Thread lifecycle, Runnable, Callable, ExecutorService, virtual threads |
| Topic 9: Functional Programming and Streams | 15% | - Optional class, primitive streams - Stream API: create, intermediate/terminal operations, parallel streams, grouping, partitioning - Lambda expressions, functional interfaces, method references |
| Topic 10: Modules and Packaging | 5% | - Module system: module-info.java, exports, requires, provides, uses - Create and use JAR files, modular and non-modular builds |
Oracle Java SE 21 Developer Professional Sample Questions:
Given:
java
List<String> frenchAuthors = new ArrayList<>();
frenchAuthors.add("Victor Hugo");
frenchAuthors.add("Gustave Flaubert");
Which compiles?
- A. Map<String, List<String>> authorsMap5 = new HashMap<String, List<String>>(); java authorsMap5.put("FR", frenchAuthors);
- B. Map<String, ? extends List<String>> authorsMap2 = new HashMap<String, ArrayList<String>> (); java authorsMap2.put("FR", frenchAuthors);
- C. var authorsMap3 = new HashMap<>();
java
authorsMap3.put("FR", frenchAuthors); - D. Map<String, ArrayList<String>> authorsMap1 = new HashMap<>();
java
authorsMap1.put("FR", frenchAuthors); - E. Map<String, List<String>> authorsMap4 = new HashMap<String, ArrayList<String>>(); java authorsMap4.put("FR", frenchAuthors);
Correct Answer: A,C,E 🗳️
Explanation: Only visible for Prep4King members. You can sign-up / login (it's free).
Given:
java
public class Test {
static int count;
synchronized Test() {
count++;
}
public static void main(String[] args) throws InterruptedException {
Runnable task = Test::new;
Thread t1 = new Thread(task);
Thread t2 = new Thread(task);
t1.start();
t2.start();
t1.join();
t2.join();
System.out.println(count);
}
}
What is the given program's output?
- A. It's always 2
- B. It's always 1
- C. It's either 0 or 1
- D. Compilation fails
- E. It's either 1 or 2
Correct Answer: D 🗳️
Explanation: Only visible for Prep4King members. You can sign-up / login (it's free).
Which two of the following aren't the correct ways to create a Stream?
- A. Stream stream = new Stream();
- B. Stream stream = Stream.ofNullable("a");
- C. Stream stream = Stream.of();
- D. Stream stream = Stream.empty();
- E. Stream stream = Stream.of("a");
- F. Stream stream = Stream.generate(() -> "a");
- G. Stream<String> stream = Stream.builder().add("a").build();
Correct Answer: A,G 🗳️
Explanation: Only visible for Prep4King members. You can sign-up / login (it's free).
Given:
java
Integer frenchRevolution = 1789;
Object o1 = new String("1789");
Object o2 = frenchRevolution;
frenchRevolution = null;
Object o3 = o2.toString();
System.out.println(o1.equals(o3));
What is printed?
- A. false
- B. A NullPointerException is thrown.
- C. Compilation fails.
- D. A ClassCastException is thrown.
- E. true
Correct Answer: E 🗳️
Explanation: Only visible for Prep4King members. You can sign-up / login (it's free).
Which of the following doesnotexist?
- A. BooleanSupplier
- B. Supplier<T>
- C. LongSupplier
- D. BiSupplier<T, U, R>
- E. DoubleSupplier
- F. They all exist.
Correct Answer: D 🗳️
Explanation: Only visible for Prep4King members. You can sign-up / login (it's free).
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