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Oracle 1z1-830 Exam Syllabus Topics:
| Section | Weight | Objectives |
|---|---|---|
| Modules and Packaging | 5% | - Create and use JAR files, modular and non-modular builds - Module system: module-info.java, exports, requires, provides, uses |
| Handling Exceptions | 8% | - Create and use custom exceptions, throw, throws - Exception hierarchy, try-catch-finally, multi-catch, try-with-resources |
| Advanced Features and Annotations | 3% | - Generics, type parameters, wildcards, type erasure - Annotations, built-in annotations, custom annotations |
| Concurrency and Multithreading | 10% | - Synchronization, locks, concurrent collections, thread safety - Thread lifecycle, Runnable, Callable, ExecutorService, virtual threads |
| Java I/O and Localization | 5% | - File I/O, NIO.2, streams, readers/writers, serialization - Resource bundles, locale, formatting messages, numbers, dates |
| 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 |
| Using Object-Oriented Concepts | 20% | - Enums, nested classes, local variable type inference - Overloading, overriding, Object class methods, immutable objects - 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 |
| Controlling Program Flow | 10% | - Decision constructs: if-else, switch expressions and statements, pattern matching - Loops: for, enhanced for, while, do-while, break, continue, return |
| 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 |
Oracle Java SE 21 Developer Professional Sample Questions:
What do the following print?
java
public class Main {
int instanceVar = staticVar;
static int staticVar = 666;
public static void main(String args[]) {
System.out.printf("%d %d", new Main().instanceVar, staticVar);
}
static {
staticVar = 42;
}
}
- A. 42 42
- B. Compilation fails
- C. 666 666
- D. 666 42
Explanation: Only visible for VCE4Dumps members. You can sign-up / login (it's free).
Which of the following suggestions compile?(Choose two.)
- A. java
public sealed class Figure
permits Circle, Rectangle {}
final sealed class Circle extends Figure {
float radius;
}
non-sealed class Rectangle extends Figure {
float length, width;
} - B. java
public sealed class Figure
permits Circle, Rectangle {}
final class Circle extends Figure {
float radius;
}
non-sealed class Rectangle extends Figure {
float length, width;
} - C. java
sealed class Figure permits Rectangle {}
final class Rectangle extends Figure {
float length, width;
} - D. java
sealed class Figure permits Rectangle {}
public class Rectangle extends Figure {
float length, width;
}
Explanation: Only visible for VCE4Dumps members. You can sign-up / login (it's free).
Given:
java
List<Long> cannesFestivalfeatureFilms = LongStream.range(1, 1945)
.boxed()
.toList();
try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
cannesFestivalfeatureFilms.stream()
.limit(25)
.forEach(film -> executor.submit(() -> {
System.out.println(film);
}));
}
What is printed?
- A. Compilation fails
- B. Numbers from 1 to 25 sequentially
- C. Numbers from 1 to 25 randomly
- D. An exception is thrown at runtime
- E. Numbers from 1 to 1945 randomly
Explanation: Only visible for VCE4Dumps members. You can sign-up / login (it's free).
Which of the following statements is correct about a final class?
- A. It cannot implement any interface.
- B. It cannot be extended by any other class.
- C. It cannot extend another class.
- D. It must contain at least a final method.
- E. The final keyword in its declaration must go right before the class keyword.
Explanation: Only visible for VCE4Dumps members. You can sign-up / login (it's free).
Given:
java
String s = " ";
System.out.print("[" + s.strip());
s = " hello ";
System.out.print("," + s.strip());
s = "h i ";
System.out.print("," + s.strip() + "]");
What is printed?
- A. [,hello,h i]
- B. [ , hello ,hi ]
- C. [,hello,hi]
- D. [ ,hello,h i]
Explanation: Only visible for VCE4Dumps members. You can sign-up / login (it's free).
