1z0-830問題集、Oracle実際の試験問題

質問 1

Which of the following suggestions compile?(Choose two.)

A. java
sealed class Figure permits Rectangle {}
public 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
public sealed class Figure
permits Circle, Rectangle {}
final sealed class Circle extends Figure {
float radius;
}
non-sealed class Rectangle extends Figure {
float length, width;
}

D. java
sealed class Figure permits Rectangle {}
final class Rectangle extends Figure {
float length, width;
}

正解: B,D

解説: (PassTest メンバーにのみ表示されます)

質問 2

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
Path path = Paths.get("file.txt");
byte[] strBytes = "Hello".getBytes();
Files.write(path, strBytes);

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

D. None of the suggestions

E. java
try (PrintWriter printWriter = new PrintWriter("file.txt")) {
printWriter.printf("Hello %s", "James");
}

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

正解: F

解説: (PassTest メンバーにのみ表示されます)

質問 3

Which of the following isn't a valid option of the jdeps command?

A. --list-deps

B. --generate-module-info

C. --print-module-deps

D. --list-reduced-deps

E. --generate-open-module

F. --check-deps

正解: F

解説: (PassTest メンバーにのみ表示されます)

質問 4

Given:
java
Stream<String> strings = Stream.of("United", "States");
BinaryOperator<String> operator = (s1, s2) -> s1.concat(s2.toUpperCase()); String result = strings.reduce("-", operator); System.out.println(result); What is the output of this code fragment?

A. -UnitedSTATES

B. United-STATES

C. United-States

D. UnitedStates

E. -UnitedStates

F. -UNITEDSTATES

G. UNITED-STATES

正解: A

解説: (PassTest メンバーにのみ表示されます)

質問 5

Given:
java
public class BoomBoom implements AutoCloseable {
public static void main(String[] args) {
try (BoomBoom boomBoom = new BoomBoom()) {
System.out.print("bim ");
throw new Exception();
} catch (Exception e) {
System.out.print("boom ");
}
}
@Override
public void close() throws Exception {
System.out.print("bam ");
throw new RuntimeException();
}
}
What is printed?

A. Compilation fails.

B. bim boom

C. bim bam boom

D. bim bam followed by an exception

E. bim boom bam

正解: C

解説: (PassTest メンバーにのみ表示されます)

質問 6

Given:
java
String textBlock = """
j \
a \t
v \s
a \
""";
System.out.println(textBlock.length());
What is the output?

A. 14

B. 10

C. 12

D. 11

正解: C

解説: (PassTest メンバーにのみ表示されます)

質問 7

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. Compilation fails.

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

C. Sum: 22.0, Max: 8.5, Avg: 5.5

D. An exception is thrown at runtime.

正解: C

解説: (PassTest メンバーにのみ表示されます)

質問 8

Which two of the following aren't the correct ways to create a Stream?

A. Stream<String> stream = Stream.builder().add("a").build();

B. Stream stream = Stream.empty();

C. Stream stream = Stream.ofNullable("a");

D. Stream stream = Stream.generate(() -> "a");

E. Stream stream = Stream.of();

F. Stream stream = new Stream();

正解: A,F

質問 9

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. ImplementingInterface

B. ExtendingClass

C. WithInstanceField

D. WithStaticField

正解: A,D

解説: (PassTest メンバーにのみ表示されます)

Oracle Java SE 21 Developer Professional - 1z0-830 模擬練習