[2024年08月]更新の1Z0-829問題集には100%厳密検証された問題と解答で合格保証もしくは全額返金
合格させるOracle 1Z0-829試験には練習テスト問題集豪華お試しセット
Oracle 1Z0-829（Java SE 17 Developer）認定試験は、Java開発者が潜在的な雇用主に彼らのスキルと知識を示す優れた方法です。この認定は世界的に認められ、経験豊富なJava開発者を採用したい雇用主にとって高く評価されています。この認定を取得することで、開発者はJavaプログラミングの専門知識を示し、業界で夢の仕事を見つける可能性を高めることができます。
試験は、150分以内に回答する必要のある60の多肢選択問題から構成されています。質問は、Java言語の基礎、オブジェクト指向プログラミングの概念、関数型プログラミング、並行性、およびI / O操作など、様々なトピックをカバーしています。試験には、instanceofのパターンマッチング、シールドクラス、レコードなど、Java SE 17で導入された新機能に関する質問も含まれます。試験に合格するには、60の質問のうち少なくとも63％または38の正解を得る必要があります。Oracle 1Z0-829認定は、Java開発者にとって貴重な資産であり、最新のJava技術における専門知識を検証し、キャリアアップを支援することができます。
Oracle 1Z0-829：Java SE 17 Developer試験は、Javaプログラミングのキャリアを追求する人にとって必須の認定です。Java SE 17プログラミング言語およびその関連ツールや技術の包括的な概要を提供します。この認定は、グローバルに認知され、ソフトウェア開発業界の雇用主に高く評価されています。
質問 # 13
Given the code fragment:
What is the result?
- A. Cat
Dog - B. A NullPointerException is thrown
Cat
Cat - C. Dog
Dog - D. Cat
null
正解：D
解説：
The answer is E because the code fragment creates a new Pet object with the name "Dog" and assigns it to the variable p. Then, it assigns p to p1. Next, it changes the name of p1 to "Cat". Then, it assigns p1 to p. Finally, it sets p to null and prints the name of p and p1. The output will be "Cat" and "null" because p is set to null and p1 still points to the Pet object with the name "Cat".
質問 # 14
Given the code fragment:
Which code fragment invokes all callable objects in the workers set?
- A.
- B.
- C.
- D.
正解：D
解説：
Explanation
The code fragment in Option C invokes all callable objects in the workers set by using the ExecutorService's invokeAll() method. This method takes a collection of Callable objects and returns a list of Future objects representing the results of the tasks. The other options are incorrect because they either use the wrong method (invokeAny() or submit()) or have syntax errors (missing parentheses or semicolons). References: AbstractExecutorService (Java SE 17 & JDK 17) - Oracle
質問 # 15
Given:
What is the result?
- A. Compilation fails
- B. wTableChair TableChair
- C. A RuntimeException is thrown
- D. Tablechair Tablechair
- E. Wtablechair tableChair
正解：A
解説：
Explanation
The code fragment will fail to compile because the class name and the constructor name do not match. The class name is Furniture, but the constructor name is Wtable. This will cause a syntax error. The correct way to define a constructor is to use the same name as the class name. Therefore, the code fragment should change the constructor name to Furniture or change the class name to Wtable.
質問 # 16
Which statement is true about migration?
- A. The required modules migrate before the modules that depend on them in a top-down ^migration.
- B. Every module is moved to the module path in a bottom-up migration.
- C. Unnamed modules are automatic modules in a top-down migration.
- D. Every module is moved to the module path in a top-down migration.
正解：B
解説：
The answer is B because a bottom-up migration is a strategy for modularizing an existing application by moving its dependencies to the module path one by one, starting from the lowest-level libraries and ending with the application itself. This way, each module can declare its dependencies on other modules using the module-info.java file, and benefit from the features of the Java Platform Module System (JPMS), such as reliable configuration, strong encapsulation, and service loading.
Option A is incorrect because a top-down migration is a strategy for modularizing an existing application by moving it to the module path first, along with its dependencies as automatic modules. Automatic modules are non-modular JAR files that are treated as modules with some limitations, such as not having a module descriptor or a fixed name. A top-down migration allows the application to use the module path without requiring all of its dependencies to be modularized first.
Option C is incorrect because a top-down migration does not require any specific order of migrating modules, as long as the application is moved first and its dependencies are moved as automatic modules. A bottom-up migration, on the other hand, requires the required modules to migrate before the modules that depend on them.
Option D is incorrect because unnamed modules are not automatic modules in any migration strategy. Unnamed modules are modules that do not have a name or a module descriptor, such as classes loaded from the class path or dynamically generated classes. Unnamed modules have unrestricted access to all other modules, but they cannot be accessed by named modules, except through reflection with reduced security checks. Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Migrating to Modules (How and When) - JavaDeploy
Java 9 Modularity: Patterns and Practices for Developing Maintainable Applications
質問 # 17
Which two code fragments compile?
- A.
- B.
- C.
- D.
- E.
正解：B、D
解説：
The two code fragments that compile are B and E. These are the only ones that use the correct syntax for declaring and initializing a var variable. The var keyword is a reserved type name that allows the compiler to infer the type of the variable based on the initializer expression. However, the var variable must have an initializer, and the initializer must not be null or a lambda expression. Therefore, option A is invalid because it does not have an initializer, option C is invalid because it has a null initializer, and option D is invalid because it has a lambda expression as an initializer. Option B is valid because it has a String initializer, and option E is valid because it has an int initializer.
https://docs.oracle.com/en/java/javase/17/language/local-variable-type-inference.html
質問 # 18
Given the code fragment:
Which code line n1, obtains the java.io.Console object?
- A.
- B.
- C.
- D.
- E.
正解：E
解説：
The code fragment is trying to obtain the java.io.Console object, which is a class that provides methods to access the character-based console device, if any, associated with the current Java virtual machine. The correct way to obtain the Console object is to call the static method Console console() in the java.lang.System class. This method returns the unique Console object associated with the current Java virtual machine, if any. Therefore, option A is correct, as it calls System.console() and assigns it to a Console variable. Reference:
https://docs.oracle.com/javase/17/docs/api/java.base/java/io/Console.html
https://docs.oracle.com/javase/17/docs/api/java.base/java/lang/System.html#console()
https://education.oracle.com/products/trackp_OCPJSE17
https://mylearn.oracle.com/ou/learning-path/java-se-17-developer/99487
質問 # 19
Given the code fragment:
What is the result?
- A. 010 optional (Newyear)
- B. True true false NewYear
- C. False true true optional (Newyear)
- D. 0110
正解：C
解説：
Explanation
The code fragment is using the stream methods allMatch, anyMatch, noneMatch, and findFirst on a list of strings called specialDays. These methods are used to perform matching operations on the elements of a stream, such as checking if all, any, or none of the elements satisfy a given predicate, or finding the first element that matches a predicate1. The predicate in this case is that the string equals "Labour" or
"Halloween". The output will be:
False: because not all of the elements in specialDays are equal to "Labour" or "Halloween".
true: because at least one of the elements in specialDays is equal to "Labour" or "Halloween".
true: because none of the elements in specialDays are equal to both "Labour" and "Halloween".
Optional[NewYear]: because the first element in specialDays that matches the predicate is "NewYear", and the findFirst method returns an Optional object that may or may not contain a non-null value2.
References: Stream (Java SE 17 & JDK 17), Optional (Java SE 17 & JDK 17)
質問 # 20
Given:
Which statement is true?
- A. The program fails to compile.
- B. The program throws outofStockException.
- C. The program throws StockException.
- D. The program throws ClassCastException
正解：A
解説：
The answer is B because the code fragment contains a syntax error that prevents it from compiling. The code fragment tries to catch a StockException in line 10, but the catch block does not have a parameter of type StockException. The catch block should have a parameter of type StockException, such as:
catch (StockException e) { // handle the exception }
This is required by the Java syntax for the catch clause, which must have a parameter that is a subclass of Throwable. Without a parameter, the catch block is invalid and causes a compilation error.
Option A is incorrect because the program does not throw a StockException, as it does not compile.
Option C is incorrect because the program does not throw an OutofStockException, as it does not compile.
Option D is incorrect because the program does not throw a ClassCastException, as it does not compile. Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
The try-with-resources Statement (The Java™ Tutorials > Essential Classes > Exceptions) The catch Blocks (The Java™ Tutorials > Essential Classes > Exceptions)
質問 # 21
Given the product class:
And the shop class:
What is the result?
- A. Cookie 3.99 2.99
- B. Compilation fails
- C. Cookie 0.0 2.99
- D. Cookie 2.99 2.99
- E. An exception is produced at runtime
- F. Cookie 0.0 0.0
正解：B
解説：
Explanation
The code fragment will fail to compile because the readObject method in the Product class is missing the
@Override annotation. The readObject method is a special method that is used to customize the deserialization process of an object. It must be declared as private, have no return type, and take a single parameter of type ObjectInputStream. It must also be annotated with @Override to indicate that it overrides the default behavior of the ObjectInputStream class. Without the @Override annotation, the compiler will treat the readObject method as a normal method and not as a deserialization hook. Therefore, the code fragment will produce a compilation error. References: Object Serialization - Oracle, [ObjectInputStream (Java SE 17 & JDK 17) - Oracle]
質問 # 22
Given the code fragment:
Which code fragment returns different values?
- A. int sum = listOfNumbers. Stream () reduce (5, (a, b) -> a + b) ;
- B. int sum = listOfNumbers. parallelStream () reduce (5, Integer:: sum) ;
- C. int sum = listOfNumbers. parallelStream () reduce ({m, n) -> m +n) orElse (5) +5;
- D. int sum = listOfNumbers. Stream () reduce (0, Integer:: sum) + 5
- E. int sum = listOfNumbers. Stream () reduce ( Integer:: sum) ; +5;
正解：E
解説：
The answer is C because the code fragment uses a different syntax and logic for the reduce operation than the other options. The reduce method in option C takes a single parameter, which is a BinaryOperator that combines two elements of the stream into one. The method returns an Optional, which may or may not contain a value depending on whether the stream is empty or not. The code fragment then adds 5 to the result of the reduce method, regardless of whether it is present or not. This may cause an exception if the Optional is empty, or produce a different value than the other options if the Optional is not empty.
The other options use a different syntax and logic for the reduce operation. They all take two parameters, which are an identity value and a BinaryOperator that combines an element of the stream with an accumulator. The method returns the final accumulator value, which is equal to the identity value if the stream is empty, or the result of applying the BinaryOperator to all elements of the stream otherwise. The code fragments then add 5 to the result of the reduce method, which will always produce a valid value.
For example, suppose listOfNumbers contains [1, 2, 3]. Then, option A will perform the following steps:
Initialize accumulator to identity value 5
Apply BinaryOperator Integer::sum to accumulator and first element: 5 + 1 = 6 Update accumulator to 6 Apply BinaryOperator Integer::sum to accumulator and second element: 6 + 2 = 8 Update accumulator to 8 Apply BinaryOperator Integer::sum to accumulator and third element: 8 + 3 = 11 Update accumulator to 11 Return final accumulator value 11 Add 5 to final accumulator value: 11 + 5 = 16 Option B will perform the same steps as option A, except using a lambda expression instead of a method reference for the BinaryOperator. Option D will perform the same steps as option A, except using parallelStream instead of stream, which may change the order of applying the BinaryOperator but not the final result. Option E will perform the same steps as option A, except using identity value 0 instead of 5.
Option C, however, will perform the following steps:
Apply BinaryOperator Integer::sum to first and second element: 1 + 2 = 3 Apply BinaryOperator Integer::sum to previous result and third element: 3 + 3 = 6 Return Optional containing final result value 6 Add 5 to Optional value: Optional.of(6) + 5 = Optional.of(11) As you can see, option C produces a different value than the other options, and also uses a different syntax and logic for the reduce operation. Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Guide to Stream.reduce()
質問 # 23
Given the code fragment:
Which action sorts the book list?
- A. At Line n2, replace compareTo () with compare ().
- B. At Line n2, replace books,sort() with books.stream().sort(0.
- C. At Line n1, convert type to mutable array type.
- D. At line n1, convert books type to mutable ArrayList type.
正解：A
解説：
Explanation
The code fragment is trying to sort a list of books using the Collections.sort() method. The correct answer is D, because the compareTo() method is not the correct way to compare two objects in a Comparator. The compare() method is the correct way to compare two objects in a Comparator and return an int value that indicates their order1. The compareTo() method is used to implement the Comparable interface, which defines the natural order of objects of a class2. The other options are incorrect because they either do not change the type of the list, which is already mutable, or they do not use the correct syntax for sorting a stream, which requires a terminal operation such as collect()3. References: Comparator (Java SE 17 & JDK 17), Comparable (Java SE 17 & JDK 17), Stream (Java SE 17 & JDK 17)
質問 # 24
Given:
What is the result?
- A. Software Game Software Game chess 0
- B. Software Game Software Game Chese 2
- C. Software game write error
- D. Software Game read error
- E. Software Game Chess 0
- F. Software Game Chess 2
正解：B
解説：
Explanation
The answer is B because the code uses the writeObject and readObject methods of the ObjectOutputStream and ObjectInputStream classes to serialize and deserialize the Game object. These methods use the default serialization mechanism, which writes and reads the state of the object's fields, including the inherited ones. Therefore, the title field of the Software class is also serialized and deserialized along with the players field of the Game class. The toString method of the Game class calls the toString method of the Software class using super.toString(), which returns the value of the title field.
Hence, when the deserialized object is printed, it shows "Software Game Software Game Chess 2".
References:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Serialization and Deserialization in Java with Example
質問 # 25
Daylight Saving Time (DST) is the practice of advancing clocks at the start of spring by one hour and adjusting them backward by one hour in autumn.
Considering that in 2021, DST in Chicago (Illinois) ended on November 7th at 2 AM, and given the fragment:
What is the output?
- A. true
true - B. true
false - C. false
true - D. False
false
正解：B
解説：
The answer is A because the code fragment uses the ZoneId and ZonedDateTime classes to create two date-time objects with the same local date-time but different zone offsets. The ZoneId class represents a time-zone ID, such as America/Chicago, and the ZonedDateTime class represents a date-time with a time-zone in the ISO-8601 calendar system. The code fragment creates two ZonedDateTime objects with the same local date-time of 2021-11-07T01:30, but different zone IDs of America/Chicago and UTC. The code fragment then compares the two objects using the equals and isEqual methods.
The equals method compares the state of two objects for equality. In this case, it compares the local date-time, zone offset, and zone ID of the two ZonedDateTime objects. Since the zone offsets and zone IDs are different, the equals method returns false.
The isEqual method compares the instant of two temporal objects for equality. In this case, it compares the instant of the two ZonedDateTime objects, which is derived from the local date-time and zone offset. Since DST in Chicago ended on November 7th at 2 AM in 2021, the local date-time of 2021-11-07T01:30 in America/Chicago corresponds to the same instant as 2021-11-07T06:30 in UTC. Therefore, the isEqual method returns true.
Hence, the output is true false. Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
ZoneId (Java Platform SE 8 )
ZonedDateTime (Java Platform SE 8 )
Time Zone & Clock Changes in Chicago, Illinois, USA
Daylight Saving Time Changes 2023 in Chicago, USA
質問 # 26
Given:
Which two should the module-info file include for it to represent the service provider interface?
- A. Exports com.transport.vehicle.cars;
- B. Requires cm.transport.vehicle,cars:
- C. Requires cm.transport.vehicle,cars:
- D. Exports com.transport.vehicle;
- E. Provides.com.transport.vehicle.cars.Car with com.transport.vehicle.cars. impt, CatImpI;
- F. Provides.com.transport.vehicle.cars.Car impl,CarImp1 to com.transport.vehicle.cars. Cars
- G. exports com.transport.vehicle.cars.Car;
正解：E、G
解説：
The answer is B and E because the module-info file should include a provides directive and an exports directive to represent the service provider interface. The provides directive declares that the module provides an implementation of a service interface, which is com.transport.vehicle.cars.Car in this case. The with clause specifies the fully qualified name of the service provider class, which is com.transport.vehicle.cars.impl.CarImpl in this case. The exports directive declares that the module exports a package, which is com.transport.vehicle.cars in this case, to make it available to other modules. The package contains the service interface that other modules can use.
Option A is incorrect because requires is not the correct keyword to declare a service provider interface. Requires declares that the module depends on another module, which is not the case here.
Option C is incorrect because it has a typo in the module name. It should be com.transport.vehicle.cars, not cm.transport.vehicle.cars.
Option D is incorrect because it has a typo in the keyword provides. It should be provides, not Provides. It also has a typo in the service interface name. It should be com.transport.vehicle.cars.Car, not com.transport.vehicle.cars.Car impl. It also has an unnecessary to clause, which is used to limit the accessibility of an exported package to specific modules.
Option F is incorrect because it exports the wrong package. It should export com.transport.vehicle.cars, not com.transport.vehicle.cars.impl. The impl package contains the service provider class, which should not be exposed to other modules.
Option G is incorrect because it exports the wrong package. It should export com.transport.vehicle.cars, not com.transport.vehicle. The vehicle package does not contain the service interface or the service provider class. Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Java Modules - Service Interface Module - GeeksforGeeks
Java Service Provider Interface | Baeldung
質問 # 27
Given the code fragments:
Which action prints Wagon : 200?
- A. At line n2, in the main method signature, add throws IoException, ClassNotFoundException.
- B. At line n3, replace readObject (0 with readLine().
- C. At line n1, implement the java.io, Serializable interface.
- D. At Line n3, replace Car with LuxurayCar.
- E. At Line n1, implement the java.io.AutoCloseable interface
- F. At line n2, in the main method signature, add throws IOException, ClassCastException.
正解：A
解説：
Explanation
The code fragment is trying to read an object from a file using the ObjectInputStream class. This class throws an IOException and a ClassNotFoundException. To handle these exceptions, the main method signature should declare that it throws these exceptions. Otherwise, the code will not compile. If the main method throws these exceptions, the code will print Wagon : 200, which is the result of calling the toString method of the LuxuryCar object that was written to the file. References: ObjectInputStream (Java SE 17 & JDK 17) - Oracle, ObjectOutputStream (Java SE 17 & JDK 17) - Oracle
質問 # 28
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