Oracle 1z0-830 Exam Syllabus Topics:
| Section | Objectives |
|---|---|
| Concurrency and Multithreading | - Thread management
|
| Core APIs | - Java standard library usage
|
| Database Connectivity (JDBC) | - Database interaction
|
| Object-Oriented Programming | - Core OOP principles
|
| Advanced Java Features (Java SE 21) | - Modern language features
|
| Java Language Fundamentals | - Java syntax and language structure
|
| Input/Output and File Handling | - NIO and file operations
|
| Exception Handling and Debugging | - Error handling mechanisms
|
Oracle Java SE 21 Developer Professional Sample Questions:
1. Given:
java
DoubleSummaryStatistics stats1 = new DoubleSummaryStatistics();
stats1.accept(4.5);
stats1.accept(6.0);
DoubleSummaryStatistics stats2 = new DoubleSummaryStatistics();
stats2.accept(3.0);
stats2.accept(8.5);
stats1.combine(stats2);
System.out.println("Sum: " + stats1.getSum() + ", Max: " + stats1.getMax() + ", Avg: " + stats1.getAverage()); What is printed?
A) Sum: 22.0, Max: 8.5, Avg: 5.0
B) An exception is thrown at runtime.
C) Sum: 22.0, Max: 8.5, Avg: 5.5
D) Compilation fails.
2. Given:
java
var _ = 3;
var $ = 7;
System.out.println(_ + $);
What is printed?
A) 10
B) It throws an exception.
C) _$
D) Compilation fails.
3. 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 ,hi ]
B) [,hello,hi]
C) [ ,hello,h i]
D) [,hello,h i]
4. 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? true; Is Car sealed? true; Is Bike sealed? true
B) Is Vehicle sealed? false; Is Car sealed? false; Is Bike sealed? false
C) Is Vehicle sealed? false; Is Car sealed? true; Is Bike sealed? true
D) Is Vehicle sealed? true; Is Car sealed? false; Is Bike sealed? false
5. Given:
java
record WithInstanceField(String foo, int bar) {
double fuz;
}
record WithStaticField(String foo, int bar) {
static double wiz;
}
record ExtendingClass(String foo) extends Exception {}
record ImplementingInterface(String foo) implements Cloneable {}
Which records compile? (Select 2)
A) ExtendingClass
B) ImplementingInterface
C) WithStaticField
D) WithInstanceField
Solutions:
| Question # 1 Answer: C | Question # 2 Answer: D | Question # 3 Answer: D | Question # 4 Answer: D | Question # 5 Answer: B,C |
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