[Q28-Q44] Use Real 1z1-829 – 100% Cover Real Exam Questions [Feb-2024]

Explanation
The code fragment is using the Java SE 17 API to get the current time and then truncating it to minutes. The result will be the current time truncated to minutes, which is why option B is correct. References:
https://education.oracle.com/products/trackp_OCPJSE17
https://mylearn.oracle.com/ou/learning-path/java-se-17-developer/99487
https://docs.oracle.com/javase/17/docs/api/java.base/java/time/Instant.html#truncatedTo(java.time.tempora

The answer is C because the code fragment given is an abstract sealed interface SInt that permits Story and Art. The correct answer is option C, which is a sealed interface Story that extends SInt and a non-sealed class Art that implements SInt. This is because a sealed interface can only be extended by the classes or interfaces that it permits, and a non-sealed class can implement a sealed interface.
Option A is incorrect because interface is misspelled as interace, and Story and Art should be capitalized as they are the names of the permitted classes or interfaces.
Option B is incorrect because public is misspelled as public, and sInd should be SInt as it is the name of the sealed interface.
Option D is incorrect because a non-sealed interface cannot extend a sealed interface, as it would violate the restriction of permitted subtypes.
Option E is incorrect because both Story and Art cannot be non-sealed interfaces, as they would also violate the restriction of permitted subtypes.
Reference:
Oracle Certified Professional: Java SE 17 Developer
Java SE 17 Developer
OCP Oracle Certified Professional Java SE 17 Developer Study Guide
Sealed Classes and Interfaces in Java 15 | Baeldung
Sealed Class in Java – Javatpoint

Explanation
The code fragment is creating a string variable “a” with the value “Hello! Java”. Then, it is printing the index of “Java” in “a”. Next, it is replacing “Hello!” with “Welcome!” in “a”. Then, it is printing the index of “Java” in “a”. Finally, it is creating a new StringBuilder object “b” with the value of “a” and printing the index of
“Java” in “b”. The output will be 8109 because the index of “Java” in “a” is 8, the index of “Java” in “a” after replacing “Hello!” with “Welcome!” is 10, and the index of “Java” in “b” is 9. References: Oracle Java SE 17 Developer source and documents: [String (Java SE 17 & JDK 17)], [StringBuilder (Java SE 17 & JDK 17)]

Explanation
The answer is D because the code fragment reads the content of the in.txt file and writes it to the out.txt file.
The content of the in.txt file is “23456789”. The code fragment uses a char array buffer of size 8 to read the content of the in.txt file. The while loop reads the content of the in.txt file and writes it to the out.txt file until the end of the file is reached. Therefore, the content of the out.txt file will be “0123456789”.

An automatic module name is derived from the name of the JAR file when it does not contain a module-info.class file. If the JAR file has an “Automatic-Module-Name” attribute in its main manifest, then its value is the module name. Otherwise, the module name is derived from the JAR file’s name by removing any version numbers and converting it to lower case. Therefore, for a JAR named display-ascii-0.2.jar, the automatic module name would be display-ascii, following these rules.

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)

Explanation
The code fragment uses the Collections.binarySearch method to search for the string “e3” in the list. The first search returns the index of the element, which is 2. The second search returns the index of the element, which is 0. The third search returns the index of the element, which is -4. The final result is
2. References: Collections (Java SE 17 & JDK 17) – Oracle

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

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)

Explanation
The code fragment is using the Stream API to perform a reduction operation on a list of ElectricProduct objects. The reduction operation consists of three parts: an identity value, an accumulator function, and a combiner function. The identity value is the initial value of the result, which is 0.0 in this case. The accumulator function is a BiFunction that takes two arguments: the current result and the current element of the stream, and returns a new result. In this case, the accumulator function is (a,b) -> a + b.getPrice (), which means that it adds the price of each element to the current result. The combiner function is a BinaryOperator that takes two partial results and combines them into one. In this case, the combiner function is (a,b) -> a + b, which means that it adds the two partial results together.
The code fragment then applies a filter operation on the stream, which returns a new stream that contains only the elements that match the given predicate. The predicate is p -> p.getPrice () > 10, which means that it selects only the elements that have a price greater than 10. The code fragment then applies a map operation on the filtered stream, which returns a new stream that contains the results of applying the given function to each element. The function is p -> p.getName (), which means that it returns the name of each element.
The code fragment then calls the collect method on the mapped stream, which performs a mutable reduction operation on the elements of the stream using a Collector. The Collector is Collectors.joining (“,”), which means that it concatenates the elements of the stream into a single String, separated by commas.
The code fragment then prints out the result of the reduction operation and the result of the collect operation, separated by a new line. The result of the reduction operation is 300.00, which is the sum of the prices of all ElectricProduct objects that have a price greater than 10. The result of the collect operation is CellPhone,ToyCar,Motor,Fan, which is the concatenation of the names of all ElectricProduct objects that have a price greater than 10.
Therefore, the output of the code fragment is:
300.00 CellPhone,ToyCar,Motor,Fan
References: Stream (Java SE 17 & JDK 17) – Oracle, Collectors (Java SE 17 & JDK 17) – Oracle

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

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)

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.

Explanation
A thread in waiting state is waiting for another thread to perform a particular action, such as calling notify() or notifyAll() on a shared object, or terminating a joined thread. A thread in waiting state can be interrupted by another thread, which will cause the waiting thread to throw an InterruptedException and return to the runnable state. Therefore, a thread in waiting state must handle InterruptedException, either by catching it or declaring it in the throws clause. References: Thread.State (Java SE 17 & JDK 17), [Thread (Java SE 17 & JDK 17)]

Explanation
The code fragment is using the switch statement with the new Java 17 syntax. The switch statement checks the value of the variable desig and executes the corresponding case statement. In this case, the value of desig is
“CTO”, which does not match any of the case labels. Therefore, the default case statement is executed, which prints “Undefined”. The other case statements are not executed, because there is no fall through in the new syntax. Therefore, the output of the code fragment is:
Undefined

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”. Reference:
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

Explanation
The code fragment is creating a string variable “s” with the value “10_00” and an integer variable “s2” with the value 10. The string “s” is using an underscore as a separator for readability, which is allowed in Java SE
171. The question is asking for two statements that can add 250 to the numeric value of “s” and assign it to an integer variable “res”. The correct answers are A and E because they use the methods parseInt and valueOf of the Integer class to convert the string “s” to an integer. Both methods interpret the string as a signed decimal integer and return the equivalent int or Integer value23. The other options are incorrect because they either use invalid syntax, such as B and C, or they do not convert the string “s” to an integer, such as D and F: References: Binary Literals (The Java™ Tutorials > Learning the Java Language > Numbers and Strings), Integer (Java SE 17 & JDK 17), Integer (Java SE 17 & JDK 17)