How does the Merge Sort algorithm behave in terms of space complexity?
- It has a space complexity of O(1) as it sorts the array in place without using additional memory.
- It has a space complexity of O(log n) because it divides the array into smaller subarrays, reducing memory usage.
- It has a space complexity of O(n) because it creates a temporary array to hold the merged subarrays.
- It has a space complexity of O(n^2) due to the need for additional memory for merging subarrays.
Merge Sort has a space complexity of O(n) because it creates a temporary array to hold the merged subarrays during the sorting process. Unlike some other sorting algorithms like Quick Sort, Merge Sort does not use a constant amount of extra memory (O(1)) or divide the memory usage logarithmically (O(log n)).
What does the Serializable interface contain?
- A set of methods for creating new objects
- A set of methods for mathematical calculations
- A set of methods for serializing objects
- A set of methods for sorting objects
The Serializable interface in Java does not contain any methods. Instead, it serves as a marker interface, indicating that the class implementing it can be serialized. Serialization allows objects to be converted into a byte stream for storage or transmission. It's used for objects that need to be saved to a file or sent over a network.
The process of defining a new exception by extending an existing exception class is known as ________.
- Customization of exception
- Exception chaining
- Exception creation
- Exception handling
In Java, when you define a new exception by extending an existing exception class, it's called "Customization of exception." This process allows you to create your own exception classes that suit your application's specific needs while maintaining compatibility with Java's exception hierarchy.
Which of the following methods is used to read data from an InputStream object connected to a socket?
- read()
- readData()
- readFromSocket()
- readStream()
To read data from an InputStream object connected to a socket, you typically use the read() method. This method reads a single byte of data and returns an integer representation of that byte. You can then cast it to the appropriate data type. The other options are not standard methods for reading from sockets.
How can one ensure that a particular section of code does not have concurrent access by multiple threads?
- Use ReentrantLock from java.util.concurrent package.
- Use Thread.sleep() to create delays.
- Use synchronized keyword on the method.
- Use volatile keyword for variables.
To ensure that a particular section of code does not have concurrent access by multiple threads, you can use the ReentrantLock class from the java.util.concurrent package. This allows you to create a lock that multiple threads can use to synchronize access to a critical section of code. Unlike synchronized methods, it provides more fine-grained control over locking.
How does the wait() method differ from the sleep() method when working with threads?
- wait() and sleep() are interchangeable; there is no difference.
- wait() and sleep() have no impact on thread execution.
- wait() is used for inter-thread communication and releases the lock, while sleep() pauses the thread and retains the lock.
- wait() is used for pausing the thread and retains the lock, while sleep() is used for inter-thread communication and releases the lock.
In Java, the wait() method is used for inter-thread communication and is typically used with synchronization mechanisms like synchronized blocks. It releases the lock and allows other threads to execute, whereas sleep() pauses the thread but retains the lock, making it unsuitable for inter-thread communication.
What is the purpose of the start() method in a JavaFX application?
- It defines the application's GUI components.
- It handles user input events.
- It initializes the application's resources.
- It is the entry point for launching the app.
The start() method is the entry point for a JavaFX application. It is automatically called by the JavaFX framework when the application starts. Within this method, you set up the initial state of your application, create the main user interface, and configure event handling. This method serves as the starting point for building your JavaFX application.
Can an abstract class have a constructor in Java?
- It depends on the class
- No
- Yes, always
- Yes, but with restrictions
Yes, an abstract class can have a constructor in Java. However, there are some restrictions. The constructor of an abstract class is typically used to initialize the fields of the abstract class, and it can be called from subclasses using the super keyword.
Consider a scenario where multiple threads are executing tasks, but the main thread needs to wait until all tasks are complete before proceeding. How can this be achieved using Future and ExecutorService?
- Use ExecutorService's awaitTermination() method to block the main thread until all tasks are completed.
- Use ExecutorService's invokeAny() method to submit tasks and block the main thread until any one of the tasks completes.
- Use ExecutorService's shutdown() method to ensure that all tasks are complete before proceeding with the main thread.
- Use invokeAll() method of ExecutorService to submit tasks and obtain a list of Future objects, then call get() method on each Future object to block the main thread until tasks are complete.
In this scenario, you can use the invokeAll() method to submit tasks and obtain a list of Future objects representing each task. Calling the get() method on each Future object will block the main thread until all tasks are complete. This allows synchronization between the main thread and the worker threads.
A thread enters the ________ state once its run() method has completed execution.
- Blocked
- Runnable
- Terminated
- Waiting
A thread enters the "Terminated" state in Java once its "run()" method has completed execution. In this state, the thread has finished its task and is no longer actively executing code.