1z0-830試験無料問題集（85題）「Oracle Java SE 21 Developer Professional 認定」

出題：1

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. C

B. D

C. A

D. E

E. None of the above

F. B

正解：E 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：2

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. Compilation fails.

B. Peugeot 807

C. An exception is thrown at runtime.

D. Peugeot

正解：A 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：3

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. Compilation fails.

C. An exception is thrown at runtime.

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

正解：A 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：4

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. WithInstanceField

B. WithStaticField

C. ExtendingClass

D. ImplementingInterface

正解：B,D 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：5

Which of the following statements is correct about a final class?

A. It must contain at least a final method.

B. It cannot be extended by any other class.

C. The final keyword in its declaration must go right before the class keyword.

D. It cannot implement any interface.

E. It cannot extend another class.

正解：B 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：6

Given:
java
public class Versailles {
int mirrorsCount;
int gardensHectares;
void Versailles() { // n1
this.mirrorsCount = 17;
this.gardensHectares = 800;
System.out.println("Hall of Mirrors has " + mirrorsCount + " mirrors."); System.out.println("The gardens cover " + gardensHectares + " hectares.");
}
public static void main(String[] args) {
var castle = new Versailles(); // n2
}
}
What is printed?

A. Nothing

B. nginx
Hall of Mirrors has 17 mirrors.
The gardens cover 800 hectares.

C. An exception is thrown at runtime.

D. Compilation fails at line n2.

E. Compilation fails at line n1.

正解：E 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：7

Given:
java
Optional<String> optionalName = Optional.ofNullable(null);
String bread = optionalName.orElse("Baguette");
System.out.print("bread:" + bread);
String dish = optionalName.orElseGet(() -> "Frog legs");
System.out.print(", dish:" + dish);
try {
String cheese = optionalName.orElseThrow(() -> new Exception());
System.out.println(", cheese:" + cheese);
} catch (Exception exc) {
System.out.println(", no cheese.");
}
What is printed?

A. Compilation fails.

B. bread:bread, dish:dish, cheese.

C. bread:Baguette, dish:Frog legs, cheese.

D. bread:Baguette, dish:Frog legs, no cheese.

正解：D 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

出題：8

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

A. --generate-module-info

B. --print-module-deps

C. --list-reduced-deps

D. --generate-open-module

E. --list-deps

F. --check-deps

正解：F 解答を投票する

解説: (GoShiken メンバーにのみ表示されます)

1z0-830試験無料問題集「Oracle Java SE 21 Developer Professional 認定」