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Oracle 1z0-830 Exam Syllabus Topics:
| Section | Weight | Objectives |
|---|---|---|
| Controlling Program Flow | 10% | - Loops: for, enhanced for, while, do-while, break, continue, return - Decision constructs: if-else, switch expressions and statements, pattern matching |
| Handling Date, Time, Text, Numeric and Boolean Values | 12% | - Use Date-Time API: LocalDate, LocalTime, LocalDateTime, Period, Duration, Instant, ZonedDateTime - Manipulate text, text blocks, String, StringBuilder and StringBuffer - Use primitives and wrapper classes, evaluate expressions and apply type conversions |
| Java I/O and Localization | 5% | - File I/O, NIO.2, streams, readers/writers, serialization - Resource bundles, locale, formatting messages, numbers, dates |
| Concurrency and Multithreading | 10% | - Synchronization, locks, concurrent collections, thread safety - Thread lifecycle, Runnable, Callable, ExecutorService, virtual threads |
| Advanced Features and Annotations | 3% | - Annotations, built-in annotations, custom annotations - Generics, type parameters, wildcards, type erasure |
| Using Object-Oriented Concepts | 20% | - Inheritance, abstract classes, sealed classes, interfaces, polymorphism - Overloading, overriding, Object class methods, immutable objects - Enums, nested classes, local variable type inference - Classes, records, objects, constructors, initializers, methods, fields, encapsulation |
| Functional Programming and Streams | 15% | - Stream API: create, intermediate/terminal operations, parallel streams, grouping, partitioning - Lambda expressions, functional interfaces, method references - Optional class, primitive streams |
| Working with Arrays and Collections | 12% | - Declare, instantiate, initialize, use arrays and multidimensional arrays - Collections Framework: List, Set, Map, Deque, Queue, sorting, searching |
| Modules and Packaging | 5% | - Module system: module-info.java, exports, requires, provides, uses - Create and use JAR files, modular and non-modular builds |
| 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:
Given:
java
public class ThisCalls {
public ThisCalls() {
this(true);
}
public ThisCalls(boolean flag) {
this();
}
}
Which statement is correct?
- A. It compiles.
- B. It does not compile.
- C. It throws an exception at runtime.
Correct Answer: B 🗳️
Explanation: Only visible for DumpsReview members. You can sign-up / login (it's free).
How would you create a ConcurrentHashMap configured to allow a maximum of 10 concurrent writer threads and an initial capacity of 42?
Which of the following options meets this requirement?
- A. None of the suggestions.
- B. var concurrentHashMap = new ConcurrentHashMap();
- C. var concurrentHashMap = new ConcurrentHashMap(42, 0.88f, 10);
- D. var concurrentHashMap = new ConcurrentHashMap(42);
- E. var concurrentHashMap = new ConcurrentHashMap(42, 10);
Correct Answer: C 🗳️
Explanation: Only visible for DumpsReview members. You can sign-up / login (it's free).
Given:
java
Runnable task1 = () -> System.out.println("Executing Task-1");
Callable<String> task2 = () -> {
System.out.println("Executing Task-2");
return "Task-2 Finish.";
};
ExecutorService execService = Executors.newCachedThreadPool();
// INSERT CODE HERE
execService.awaitTermination(3, TimeUnit.SECONDS);
execService.shutdownNow();
Which of the following statements, inserted in the code above, printsboth:
"Executing Task-2" and "Executing Task-1"?
- A. execService.submit(task2);
- B. execService.execute(task2);
- C. execService.call(task1);
- D. execService.run(task2);
- E. execService.submit(task1);
- F. execService.run(task1);
- G. execService.execute(task1);
- H. execService.call(task2);
Correct Answer: A,E 🗳️
Explanation: Only visible for DumpsReview members. You can sign-up / login (it's free).
Given:
java
sealed class Vehicle permits Car, Bike {
}
non-sealed class Car extends Vehicle {
}
final class Bike extends Vehicle {
}
public class SealedClassTest {
public static void main(String[] args) {
Class<?> vehicleClass = Vehicle.class;
Class<?> carClass = Car.class;
Class<?> bikeClass = Bike.class;
System.out.print("Is Vehicle sealed? " + vehicleClass.isSealed() +
"; Is Car sealed? " + carClass.isSealed() +
"; Is Bike sealed? " + bikeClass.isSealed());
}
}
What is printed?
- A. Is Vehicle sealed? false; Is Car sealed? true; Is Bike sealed? true
- B. Is Vehicle sealed? true; Is Car sealed? false; Is Bike sealed? false
- C. Is Vehicle sealed? true; Is Car sealed? true; Is Bike sealed? true
- D. Is Vehicle sealed? false; Is Car sealed? false; Is Bike sealed? false
Correct Answer: B 🗳️
Explanation: Only visible for DumpsReview members. You can sign-up / login (it's free).
Given:
java
package vehicule.parent;
public class Car {
protected String brand = "Peugeot";
}
and
java
package vehicule.child;
import vehicule.parent.Car;
public class MiniVan extends Car {
public static void main(String[] args) {
Car car = new Car();
car.brand = "Peugeot 807";
System.out.println(car.brand);
}
}
What is printed?
- A. An exception is thrown at runtime.
- B. Peugeot
- C. Compilation fails.
- D. Peugeot 807
Correct Answer: C 🗳️
Explanation: Only visible for DumpsReview members. You can sign-up / login (it's free).
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