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Oracle 1z0-830 Exam Syllabus Topics:
| Section | Weight | Objectives |
|---|---|---|
| Using Object-Oriented Concepts | 20% | - Overloading, overriding, Object class methods, immutable objects - Enums, nested classes, local variable type inference - Inheritance, abstract classes, sealed classes, interfaces, polymorphism - Classes, records, objects, constructors, initializers, methods, fields, encapsulation |
| Working with Arrays and Collections | 12% | - Collections Framework: List, Set, Map, Deque, Queue, sorting, searching - Declare, instantiate, initialize, use arrays and multidimensional arrays |
| Concurrency and Multithreading | 10% | - Thread lifecycle, Runnable, Callable, ExecutorService, virtual threads - Synchronization, locks, concurrent collections, thread safety |
| Modules and Packaging | 5% | - Module system: module-info.java, exports, requires, provides, uses - Create and use JAR files, modular and non-modular builds |
| Handling Date, Time, Text, Numeric and Boolean Values | 12% | - Use primitives and wrapper classes, evaluate expressions and apply type conversions - Manipulate text, text blocks, String, StringBuilder and StringBuffer - Use Date-Time API: LocalDate, LocalTime, LocalDateTime, Period, Duration, Instant, ZonedDateTime |
| Controlling Program Flow | 10% | - Decision constructs: if-else, switch expressions and statements, pattern matching - Loops: for, enhanced for, while, do-while, break, continue, return |
| Advanced Features and Annotations | 3% | - Generics, type parameters, wildcards, type erasure - Annotations, built-in annotations, custom annotations |
| Handling Exceptions | 8% | - Create and use custom exceptions, throw, throws - Exception hierarchy, try-catch-finally, multi-catch, try-with-resources |
| 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% | - Optional class, primitive streams - Stream API: create, intermediate/terminal operations, parallel streams, grouping, partitioning - Lambda expressions, functional interfaces, method references |
Oracle Java SE 21 Developer Professional Sample Questions:
Consider the following methods to load an implementation of MyService using ServiceLoader. Which of the methods are correct? (Choose all that apply)
- A. MyService service = ServiceLoader.services(MyService.class).getFirstInstance();
- B. MyService service = ServiceLoader.load(MyService.class).iterator().next();
- C. MyService service = ServiceLoader.getService(MyService.class);
- D. MyService service = ServiceLoader.load(MyService.class).findFirst().get();
Explanation: Only visible for ValidExam members. You can sign-up / login (it's free).
Which of the following statements oflocal variables declared with varareinvalid?(Choose 4)
- A. var h = (g = 7);
- B. var e;
- C. var d[] = new int[4];
- D. var f = { 6 };
- E. var a = 1;(Valid: var correctly infers int)
- F. var b = 2, c = 3.0;
Explanation: Only visible for ValidExam 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 either 0 or 1
- B. It's always 2
- C. It's either 1 or 2
- D. It's always 1
- E. Compilation fails
Explanation: Only visible for ValidExam members. You can sign-up / login (it's free).
Given:
java
interface Calculable {
long calculate(int i);
}
public class Test {
public static void main(String[] args) {
Calculable c1 = i -> i + 1; // Line 1
Calculable c2 = i -> Long.valueOf(i); // Line 2
Calculable c3 = i -> { throw new ArithmeticException(); }; // Line 3
}
}
Which lines fail to compile?
- A. The program successfully compiles
- B. Line 1 only
- C. Line 2 only
- D. Line 1 and line 2
- E. Line 1 and line 3
- F. Line 2 and line 3
- G. Line 3 only
Explanation: Only visible for ValidExam members. You can sign-up / login (it's free).
Given:
java
public class BoomBoom implements AutoCloseable {
public static void main(String[] args) {
try (BoomBoom boomBoom = new BoomBoom()) {
System.out.print("bim ");
throw new Exception();
} catch (Exception e) {
System.out.print("boom ");
}
}
@Override
public void close() throws Exception {
System.out.print("bam ");
throw new RuntimeException();
}
}
What is printed?
- A. bim bam boom
- B. Compilation fails.
- C. bim bam followed by an exception
- D. bim boom
- E. bim boom bam
Explanation: Only visible for ValidExam members. You can sign-up / login (it's free).
