Java SE 21 Developer Professional (1z1-830) Free Practice Test

Question 1

Which of the followingisn'ta correct way to write a string to a file?

A. java
try (FileWriter writer = new FileWriter("file.txt")) {
writer.write("Hello");
}

B. java
try (FileOutputStream outputStream = new FileOutputStream("file.txt")) { byte[] strBytes = "Hello".getBytes(); outputStream.write(strBytes);
}

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. None of the suggestions

F. java
try (BufferedWriter writer = new BufferedWriter("file.txt")) {
writer.write("Hello");
}

Correct Answer: F

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Question 2

Given:
java
var counter = 0;
do {
System.out.print(counter + " ");
} while (++counter < 3);
What is printed?

A. An exception is thrown.

B. 0 1 2

C. 0 1 2 3

D. Compilation fails.

E. 1 2 3

F. 1 2 3 4

Correct Answer: B

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Question 3

Given:
java
interface SmartPhone {
boolean ring();
}
class Iphone15 implements SmartPhone {
boolean isRinging;
boolean ring() {
isRinging = !isRinging;
return isRinging;
}
}
Choose the right statement.

A. SmartPhone interface does not compile

B. Iphone15 class does not compile

C. An exception is thrown at running Iphone15.ring();

D. Everything compiles

Correct Answer: B

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Question 4

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: 5.5

B. Sum: 22.0, Max: 8.5, Avg: 5.0

C. An exception is thrown at runtime.

D. Compilation fails.

Correct Answer: A

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Question 5

You are working on a module named perfumery.shop that depends on another module named perfumery.
provider.
The perfumery.shop module should also make its package perfumery.shop.eaudeparfum available to other modules.
Which of the following is the correct file to declare the perfumery.shop module?

A. File name: module-info.java
java
module perfumery.shop {
requires perfumery.provider;
exports perfumery.shop.eaudeparfum;
}

B. File name: module.java
java
module shop.perfumery {
requires perfumery.provider;
exports perfumery.shop.eaudeparfum;
}

C. File name: module-info.perfumery.shop.java
java
module perfumery.shop {
requires perfumery.provider;
exports perfumery.shop.eaudeparfum.*;
}

Correct Answer: A

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Question 6

Which methods compile?

A. ```java public List<? extends IOException> getListExtends() { return new ArrayList<Exception>(); } csharp

B. ```java
public List<? super IOException> getListSuper() {
return new ArrayList<FileNotFoundException>();
}

C. ```java public List<? super IOException> getListSuper() { return new ArrayList<Exception>(); } csharp

D. ```java
public List<? extends IOException> getListExtends() {
return new ArrayList<FileNotFoundException>();
}

Correct Answer: C,D

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Question 7

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,h i]

C. [ , hello ,hi ]

D. [ ,hello,h i]

Correct Answer: B

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Question 8

Given:
java
public class OuterClass {
String outerField = "Outer field";
class InnerClass {
void accessMembers() {
System.out.println(outerField);
}
}
public static void main(String[] args) {
System.out.println("Inner class:");
System.out.println("------------");
OuterClass outerObject = new OuterClass();
InnerClass innerObject = new InnerClass(); // n1
innerObject.accessMembers(); // n2
}
}
What is printed?

A. Nothing

B. Compilation fails at line n2.

C. Compilation fails at line n1.

D. An exception is thrown at runtime.

E. markdown
Inner class:
------------
Outer field

Correct Answer: C

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Question 9

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. Numbers from 1 to 25 randomly

B. Numbers from 1 to 25 sequentially

C. Numbers from 1 to 1945 randomly

D. An exception is thrown at runtime

E. Compilation fails

Correct Answer: A

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Oracle Java SE 21 Developer Professional (1z1-830) Free Practice Test