Java SE 11 Developer (OCP) Free Sample Questions

The try-with-resources statement is designed for this exact purpose. However, returning the resource from within the try block is problematic because the resource will be closed before the caller can use it. The correct approach is to use a method that returns the stream and rely on the caller to manage its lifecycle, or to perform the reading within the block itself. Given the options, this is a trick question about the scope of try-with-resources. The most correct pattern is not returning the resource, but if forced to choose from flawed options that attempt to solve the problem, the question intent is likely about recognizing the try-with-resources syntax. Correction: The question asks for an implementation that returns a reader. A better implementation would pass a Consumer to process the reader's contents inside the try-with-resources block. However, amongst the given choices, the question is flawed. The most plausible intended answer is the one using Files.newBufferedReader directly, but it must be understood that the resource management is now the caller's responsibility. Let's re-evaluate the question. The question is testing the Files.newBufferedReader method combined with try-with-resources. The only syntactically valid option that uses the modern java.nio.file API and addresses resource management is the one using Files.newBufferedReader. The correct way to use it is to pass the reader to a consumer inside the block. But if the goal is to return it, the try-with-resources block cannot be used in the method itself. The best option among the choices that directly addresses the prompt is to simply return the result of Files.newBufferedReader(p), and document that the caller must close it. Let's assume the question is flawed and seeks the most modern API usage. The factory method Files.newBufferedReader(p) is the most direct way to get a BufferedReader from a Path.

To implement the service locator pattern in JPMS, the consumer module (com.finance.core) must declare that it uses the service interface. The provider module (com.finance.persistence) must declare that it provides an implementation for that service interface using the with keyword. This decouples the modules, as the core module does not need a requires directive for the persistence module.

This code snippet is vulnerable to Insecure Direct Object Reference (IDOR). It directly uses the user-provided userId to fetch data from the database without verifying that the authenticated user is authorized to access that specific user's data. An attacker could simply change the userId in the URL to access another user's information. The other options show proper input validation or correct authorization checks.

This statement is true. The Java Language Specification dictates that in a try-with-resources statement, resources are closed in the opposite order in which they were initialized. This is analogous to how finally blocks would be nested, ensuring that resources that depend on other resources are closed first.

The executor.invokeAll(tasks) method returns a List >. To process the results, you must stream this list. The Future::get method is a blocking call that throws checked exceptions (InterruptedException, ExecutionException), which cannot be used directly in a standard map operation without handling. The correct approach is to use a lambda block within mapToLong (for efficiency) that wraps the future.get() call in a try-catch block and re-throws any exception as an unchecked exception, or handles it appropriately. This option correctly demonstrates this pattern.

NumberFormat is an abstract class and cannot be instantiated directly with new. The correct way to obtain a locale-specific formatter, especially for currency, is by using the static factory method NumberFormat.getCurrencyInstance(locale). This ensures that the correct currency symbol, grouping separators, and decimal separators are used according to the rules of the specified Locale.

This question tests the difference between method overriding (dynamic dispatch) and field hiding (static dispatch). When device.getType() is called, polymorphism ensures the overridden method in the Phone class is executed, returning "mobile". However, when device.type is accessed, the reference type (Device) determines which field is used, not the object type (Phone). Therefore, the type field from the Device class is accessed, which is "electronic".

The Collectors.groupingBy() collector is specifically designed for this purpose. It takes a classification function (in this case, Order::getCustomer) and groups the elements of the stream into a Map. The keys of the map are the results of applying the classification function, and the values are Lists of the stream elements that produced each key.

To make an annotation available at runtime through reflection, its retention policy must be set to RetentionPolicy.RUNTIME. To ensure the annotation is included in the output of documentation tools like Javadoc, the @Documented meta-annotation must be applied.

The for-each loop (or enhanced for loop) in Java works with any object whose class implements the java.lang.Iterable interface. This interface has a single abstract method, iterator(), which must return an instance of java.util.Iterator. The loop then uses this iterator to traverse the elements.