Which keyword is used in Java to test a condition?
- check
- if
- test
- verify
In Java, the if keyword is used to test a condition. It allows you to execute a block of code only if the condition specified inside the parentheses evaluates to true. The if statement is fundamental for implementing conditional logic in Java programs.
What is the purpose of the finally block in Java exception handling?
- To always execute code
- To catch exceptions
- To handle checked exceptions
- To throw exceptions
The finally block in Java exception handling is used to ensure that a certain block of code is executed regardless of whether an exception is thrown or not. It is typically used to perform cleanup actions, such as closing resources.
Which method can be used to temporarily pause the execution of a thread for a specified time?
- pause()
- sleep()
- stop()
- yield()
The sleep() method in Java is used to temporarily pause the execution of a thread for a specified amount of time. It's a way to introduce delays in a program and is often used for synchronization or timing purposes. The other options are not used for pausing threads in this manner.
The @FunctionalInterface annotation is used to indicate that an interface is to be used with ________.
- Annotations
- Generics
- Lambdas
- Threads
The @FunctionalInterface annotation is used to indicate that an interface is intended to be used with lambda expressions. It serves as a marker for functional interfaces, making it clear that they are designed to be used in lambda expressions.
The ______ interface in Java represents the result of an asynchronous computation.
- Callable
- Executor
- Future
- Runnable
In Java, the Future interface represents the result of an asynchronous computation. It allows you to retrieve the result or handle exceptions once the computation is complete. A Callable is used to perform a task and return a result, and a Runnable is used to represent a task that can be executed asynchronously, but neither of them directly represents the result of the computation. The Executor interface is used to execute tasks, not represent results.
Consider a scenario where you are required to store a large number of decimal values with high precision for a financial application. Which data type would be preferable and why?
- BigDecimal
- double
- float
- long
In a financial application, precision is crucial. The double data type can store decimal values but may not provide the necessary precision due to its limited number of significant digits. BigDecimal is preferred in such scenarios because it offers arbitrary precision and is ideal for financial calculations where rounding errors need to be minimized. float and long do not provide the required precision for financial calculations.
In a multi-threaded server application, what could be a potential issue if each thread opens its own database connection via a socket?
- Reduced resource consumption as each thread manages its own connection.
- Improved concurrency and performance due to isolated connections.
- Increased risk of resource contention and exhaustion.
- Guaranteed data consistency and reliability.
In a multi-threaded server application, opening a separate database connection for each thread (option c) can lead to issues like resource contention and exhaustion. This approach can consume a significant number of resources and potentially cause performance problems. The other options (a, b, and d) do not accurately describe the issues associated with this practice.
How does the behavior of CachedThreadPool differ from that of FixedThreadPool in terms of thread creation and task management?
- CachedThreadPool creates a fixed number of threads and assigns one to each submitted task.
- CachedThreadPool creates new threads as needed and reuses previously constructed ones.
- FixedThreadPool creates a fixed number of threads and assigns one to each submitted task.
- FixedThreadPool creates new threads as needed and reuses previously constructed ones.
The behavior of CachedThreadPool differs from FixedThreadPool in that it dynamically creates new threads as needed and reuses previously constructed ones. This is suitable for tasks with variable workload. In contrast, FixedThreadPool maintains a fixed number of threads, each assigned to a task, making it ideal for tasks with a consistent workload.
Consider a scenario where you have to develop a JavaFX application that should adapt to different screen sizes. How would you approach the design and layout to ensure that the application is responsive and the UI adjusts dynamically?
- Create separate layouts for each screen size and switch between them based on the detected screen size.
- Set fixed pixel sizes for all UI elements to ensure consistent appearance across different screen sizes.
- Use JavaFX layout containers like VBox and HBox along with percentage-based sizing and responsive design principles.
- Use absolute positioning for UI elements to maintain precise control over their placement.
To create a responsive JavaFX application, you should use layout containers like VBox and HBox and design with percentage-based sizing to allow elements to adjust dynamically. Responsive design principles are essential for accommodating various screen sizes. Fixed pixel sizes, separate layouts, and absolute positioning are not recommended for achieving responsiveness.
When would you prefer byte streams over character streams while performing I/O operations in Java?
- When dealing with binary data and non-text files, such as images or audio.
- When working with XML or HTML files that contain text and tags.
- When you need to perform text-based operations, like reading and writing characters.
- When you want to handle file I/O in a platform-independent manner.
Byte streams are suitable for reading and writing binary data, while character streams are used for handling text data. Byte streams are ideal for handling non-text files, like images or audio, where individual bytes matter. Character streams are used for text files and automatically handle character encoding.