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Oracle Java SE 21 Developer Professional 考生最常問的問題

最新的 Java SE 1z0-830 免費考試真題：

問題 #1

Given:
java
int post = 5;
int pre = 5;
int postResult = post++ + 10;
int preResult = ++pre + 10;
System.out.println("postResult: " + postResult +
", preResult: " + preResult +
", Final value of post: " + post +
", Final value of pre: " + pre);
What is printed?

A. postResult: 16, preResult: 16, Final value of post: 6, Final value of pre: 6
B. postResult: 16, preResult: 15, Final value of post: 6, Final value of pre: 5
C. postResult: 15, preResult: 16, Final value of post: 6, Final value of pre: 6
D. postResult: 15, preResult: 16, Final value of post: 5, Final value of pre: 6

問題 #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. None of the suggestions
C. java
try (PrintWriter printWriter = new PrintWriter("file.txt")) {
printWriter.printf("Hello %s", "James");
}
D. java
try (BufferedWriter writer = new BufferedWriter("file.txt")) {
writer.write("Hello");
}
E. java
try (FileOutputStream outputStream = new FileOutputStream("file.txt")) { byte[] strBytes = "Hello".getBytes(); outputStream.write(strBytes);
}
F. java
Path path = Paths.get("file.txt");
byte[] strBytes = "Hello".getBytes();
Files.write(path, strBytes);

問題 #3

Given:
java
StringBuilder result = Stream.of("a", "b")
.collect(
() -> new StringBuilder("c"),
StringBuilder::append,
(a, b) -> b.append(a)
);
System.out.println(result);
What is the output of the given code fragment?

A. bca
B. cbca
C. cba
D. acb
E. abc
F. bac
G. cacb

問題 #4

Given:
java
List<Integer> integers = List.of(0, 1, 2);
integers.stream()
.peek(System.out::print)
.limit(2)
.forEach(i -> {});
What is the output of the given code fragment?

A. 012
B. Compilation fails
C. An exception is thrown
D. 01
E. Nothing

問題 #5

Which three of the following are correct about the Java module system?

A. The unnamed module can only access packages defined in the unnamed module.
B. If a package is defined in both a named module and the unnamed module, then the package in the unnamed module is ignored.
C. The unnamed module exports all of its packages.
D. If a request is made to load a type whose package is not defined in any known module, then the module system will attempt to load it from the classpath.
E. Code in an explicitly named module can access types in the unnamed module.
F. We must add a module descriptor to make an application developed using a Java version prior to SE9 run on Java 11.

問題與答案：