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Oracle 1z0-830 Exam Syllabus Topics:
| Section | Objectives |
|---|---|
| Topic 1: Java Concurrency | - Use virtual threads - Create and manage threads - Work with concurrent collections and executors |
| Topic 2: Functional Programming | - Process data using Stream API - Work with functional interfaces - Use lambda expressions and method references |
| Topic 3: Handling Date, Time, Text, Numeric and Boolean Values | - Use String, StringBuilder, and related APIs - Work with primitive wrappers and number formatting - Use date, time, duration, period, and localization APIs |
| Topic 4: Object-Oriented Programming | - Implement encapsulation and abstraction - Create and use classes, interfaces, enums, and records - Apply inheritance and polymorphism |
| Topic 5: Controlling Program Flow | - Apply decision statements and loops - Work with records and sealed classes - Use switch expressions and pattern matching |
| Topic 6: Annotations and JDBC | - Use built-in and custom annotations - Connect to databases using JDBC - Execute SQL operations and process results |
| Topic 7: Collections and Generics | - Use sequenced collections and maps - Apply generics and bounded types - Use List, Set, Map, Queue, and Deque implementations |
| Topic 8: Modules and Packaging | - Manage dependencies and exports - Create and use Java modules - Package and deploy applications |
| Topic 9: Exception Handling | - Handle checked and unchecked exceptions - Create custom exceptions - Use try-with-resources |
| Topic 10: Java I/O and NIO | - Process file system resources - Read and write files - Use Path, Files, and related APIs |
Oracle Java SE 21 Developer Professional Sample Questions:
Which StringBuilder variable fails to compile?
java
public class StringBuilderInstantiations {
public static void main(String[] args) {
var stringBuilder1 = new StringBuilder();
var stringBuilder2 = new StringBuilder(10);
var stringBuilder3 = new StringBuilder("Java");
var stringBuilder4 = new StringBuilder(new char[]{'J', 'a', 'v', 'a'});
}
}
- A. stringBuilder3
- B. stringBuilder2
- C. stringBuilder1
- D. None of them
- E. stringBuilder4
Explanation: Only visible for Test4Engine 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 1
- B. It's always 2
- C. It's either 0 or 1
- D. Compilation fails
- E. It's either 1 or 2
Explanation: Only visible for Test4Engine 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. Line 2 and line 3
- B. The program successfully compiles
- C. Line 1 and line 3
- D. Line 1 only
- E. Line 2 only
- F. Line 3 only
- G. Line 1 and line 2
Explanation: Only visible for Test4Engine members. You can sign-up / login (it's free).
Which of the followingisn'ta correct way to write a string to a file?
- A. None of the suggestions
- B. java
try (BufferedWriter writer = new BufferedWriter("file.txt")) {
writer.write("Hello");
} - C. java
try (PrintWriter printWriter = new PrintWriter("file.txt")) {
printWriter.printf("Hello %s", "James");
} - D. java
Path path = Paths.get("file.txt");
byte[] strBytes = "Hello".getBytes();
Files.write(path, strBytes); - E. java
try (FileWriter writer = new FileWriter("file.txt")) {
writer.write("Hello");
} - F. java
try (FileOutputStream outputStream = new FileOutputStream("file.txt")) { byte[] strBytes = "Hello".getBytes(); outputStream.write(strBytes);
}
Explanation: Only visible for Test4Engine members. You can sign-up / login (it's free).
Given:
java
interface A {
default void ma() {
}
}
interface B extends A {
static void mb() {
}
}
interface C extends B {
void ma();
void mc();
}
interface D extends C {
void md();
}
interface E extends D {
default void ma() {
}
default void mb() {
}
default void mc() {
}
}
Which interface can be the target of a lambda expression?
- A. A
- B. D
- C. E
- D. None of the above
- E. B
- F. C
Explanation: Only visible for Test4Engine members. You can sign-up / login (it's free).
