1z1-830試験無料問題集（85題）「Oracle Java SE 21 Developer Professional 認定」

出題：1

Given:
java
List<String> l1 = new ArrayList<>(List.of("a", "b"));
List<String> l2 = new ArrayList<>(Collections.singletonList("c"));
Collections.copy(l1, l2);
l2.set(0, "d");
System.out.println(l1);
What is the output of the given code fragment?

A. [d]

B. [a, b]

C. An UnsupportedOperationException is thrown

D. [c, b]

E. An IndexOutOfBoundsException is thrown

F. [d, b]

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：2

Given:
java
try (FileOutputStream fos = new FileOutputStream("t.tmp");
ObjectOutputStream oos = new ObjectOutputStream(fos)) {
fos.write("Today");
fos.writeObject("Today");
oos.write("Today");
oos.writeObject("Today");
} catch (Exception ex) {
// handle exception
}
Which statement compiles?

A. fos.writeObject("Today");

B. fos.write("Today");

C. oos.write("Today");

D. oos.writeObject("Today");

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：3

What do the following print?
java
public class Main {
int instanceVar = staticVar;
static int staticVar = 666;
public static void main(String args[]) {
System.out.printf("%d %d", new Main().instanceVar, staticVar);
}
static {
staticVar = 42;
}
}

A. Compilation fails

B. 42 42

C. 666 666

D. 666 42

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：4

Which methods compile?

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

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

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

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

正解：C,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

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,h i]

B. [ , hello ,hi ]

C. [,hello,h i]

D. [,hello,hi]

正解：C 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
DoubleStream doubleStream = DoubleStream.of(3.3, 4, 5.25, 6.66);
Predicate<Double> doublePredicate = d -> d < 5;
System.out.println(doubleStream.anyMatch(doublePredicate));
What is printed?

A. An exception is thrown at runtime

B. Compilation fails

C. true

D. false

E. 3.3

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：7

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

A. Stream stream = Stream.empty();

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

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

D. Stream stream = new Stream();

E. Stream stream = Stream.of();

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

正解：D,F 解答を投票する

出題：8

Given:
java
var deque = new ArrayDeque<>();
deque.add(1);
deque.add(2);
deque.add(3);
deque.add(4);
deque.add(5);
System.out.print(deque.peek() + " ");
System.out.print(deque.poll() + " ");
System.out.print(deque.pop() + " ");
System.out.print(deque.element() + " ");
What is printed?

A. 1 1 1 1

B. 1 1 2 2

C. 1 5 5 1

D. 1 1 2 3

E. 5 5 2 3

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：9

Given:
java
var frenchCities = new TreeSet<String>();
frenchCities.add("Paris");
frenchCities.add("Marseille");
frenchCities.add("Lyon");
frenchCities.add("Lille");
frenchCities.add("Toulouse");
System.out.println(frenchCities.headSet("Marseille"));
What will be printed?

A. Compilation fails

B. [Lyon, Lille, Toulouse]

C. [Paris, Toulouse]

D. [Paris]

E. [Lille, Lyon]

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)

1z1-830試験無料問題集「Oracle Java SE 21 Developer Professional 認定」