最新Java SE 1z0-830考試題庫，Oracle 1z0-830課程的擬真試題下載

問題1
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. oos.writeObject("Today");

B. fos.writeObject("Today");

C. fos.write("Today");

D. oos.write("Today");

正確答案: A

說明：（僅 NewDumps 成員可見）

問題2
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>();
}

正確答案: C,D

說明：（僅 NewDumps 成員可見）

問題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. 42 42

B. Compilation fails

C. 666 42

D. 666 666

正確答案: A

說明：（僅 NewDumps 成員可見）

問題4
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. An exception is thrown at runtime.

B. Compilation fails at line n2.

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

D. Nothing

E. Compilation fails at line n1.

正確答案: E

說明：（僅 NewDumps 成員可見）

問題5
Which of the following methods of java.util.function.Predicate aredefault methods?

A. test(T t)

B. not(Predicate<? super T> target)

C. and(Predicate<? super T> other)

D. negate()

E. or(Predicate<? super T> other)

F. isEqual(Object targetRef)

正確答案: C,D,E

說明：（僅 NewDumps 成員可見）

問題6
Given:
java
Deque<Integer> deque = new ArrayDeque<>();
deque.offer(1);
deque.offer(2);
var i1 = deque.peek();
var i2 = deque.poll();
var i3 = deque.peek();
System.out.println(i1 + " " + i2 + " " + i3);
What is the output of the given code fragment?

A. An exception is thrown.

B. 2 2 1

C. 1 1 2

D. 1 1 1

E. 2 1 2

F. 1 2 2

G. 1 2 1

H. 2 2 2

I. 2 1 1

正確答案: F

說明：（僅 NewDumps 成員可見）

問題7
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. An exception is thrown at runtime

B. Compilation fails

C. Numbers from 1 to 25 sequentially

D. Numbers from 1 to 25 randomly

E. Numbers from 1 to 1945 randomly

正確答案: D

說明：（僅 NewDumps 成員可見）

問題8
Given:
java
var sList = new CopyOnWriteArrayList<Customer>();
Which of the following statements is correct?

A. The CopyOnWriteArrayList class is a thread-safe variant of ArrayList where all mutative operations are implemented by making a fresh copy of the underlying array.

B. The CopyOnWriteArrayList class's iterator reflects all additions, removals, or changes to the list since the iterator was created.

C. The CopyOnWriteArrayList class is not thread-safe and does not prevent interference amongconcurrent threads.

D. The CopyOnWriteArrayList class does not allow null elements.

E. Element-changing operations on iterators of CopyOnWriteArrayList, such as remove, set, and add, are supported and do not throw UnsupportedOperationException.

正確答案: A

說明：（僅 NewDumps 成員可見）

問題9
Given:
java
import java.io.*;
class A implements Serializable {
int number = 1;
}
class B implements Serializable {
int number = 2;
}
public class Test {
public static void main(String[] args) throws Exception {
File file = new File("o.ser");
A a = new A();
var oos = new ObjectOutputStream(new FileOutputStream(file));
oos.writeObject(a);
oos.close();
var ois = new ObjectInputStream(new FileInputStream(file));
B b = (B) ois.readObject();
ois.close();
System.out.println(b.number);
}
}
What is the given program's output?

A. Compilation fails

B. NotSerializableException

C. 1

D. 2

E. ClassCastException

正確答案: E

說明：（僅 NewDumps 成員可見）

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