Which method is used to retrieve the protocol type of a URL in Java?
- fetchProtocol()
- getProtocol()
- getURLProtocol()
- retrieveProtocol()
In Java, to retrieve the protocol type of a URL, you should use the getProtocol() method of the URL class. It returns a String containing the protocol, such as "http," "https," "ftp," etc. The other options do not exist as valid methods for this purpose.
Is it possible to extend a class defined as final?
- No, you cannot extend a class that is declared as final.
- Yes, you can extend a final class.
- You can extend a final class only in the same package.
- You can extend a final class, but it requires special annotations.
In Java, a class declared as "final" cannot be extended. The "final" keyword indicates that the class cannot be subclassed. Attempting to extend a final class will result in a compile-time error. This feature is often used when you want to prevent further modification or extension of a class, such as in utility classes or classes that are critical to the design.
The method getInputStream() returns an input stream that reads from the ________.
- URL
- output stream
- remote object
- socket
The getInputStream() method in Java returns an input stream that allows you to read data from the remote object referred to by the URL. This is commonly used in HTTP connections to read the response data from a server. The other options do not represent what this method returns.
If a superclass method does not throw an exception, can the overridden method in the subclass throw an exception?
- No, it cannot throw any exception
- No, it cannot throw any exception
- Yes, it can throw any exception
- Yes, it can throw any exception
In Java, if a superclass method does not declare any exceptions, the overridden method in the subclass cannot throw checked exceptions that are broader in scope than those of the superclass method. This rule is in place to ensure that the subclass does not introduce unexpected exceptions.
How does the "diamond problem" get resolved in Java while using interfaces?
- In Java, the "diamond problem" cannot be resolved, and it leads to a compilation error.
- Java resolves the "diamond problem" by allowing classes to implement multiple interfaces with conflicting method signatures.
- The "diamond problem" is resolved by introducing explicit casting to specify which method to call when there is a conflict.
- The "diamond problem" is resolved by renaming the conflicting methods in the implementing class.
In Java, the "diamond problem" occurs when a class inherits from two or more classes that have a common ancestor with a method of the same name. To resolve this, Java allows classes to implement multiple interfaces with conflicting method signatures. This forces the implementing class to provide its own implementation, and it must explicitly call the desired method using the interface name.
In which sorting algorithm do larger or smaller elements "bubble" to the top of the array?
- Bubble Sort
- Merge Sort
- Quick Sort
- Selection Sort
In Bubble Sort, larger or smaller elements "bubble" to the top of the array as the algorithm repeatedly passes through the list and swaps adjacent elements if they are in the wrong order. The "bubbling" process continues until the entire list is sorted. Bubble Sort is so named due to this bubbling behavior.
What is the output of the following code snippet: int[][] arr = new int[3][2]; System.out.println(arr.length);?
- 2
- 3
- 6
- The code will result in a compilation error.
In the given code, arr.length returns the number of rows in the 2D array. Here, arr is declared as a 2D array with 3 rows and 2 columns, so it prints 3, which is the number of rows.
In which scenarios is it recommended to use synchronized blocks instead of synchronized methods?
- When you don't want to use synchronization at all.
- When you want to apply synchronization to a specific section of code within a method, providing more fine-grained control.
- When you want to synchronize an entire method for simplicity.
- When you want to synchronize multiple methods simultaneously.
Synchronized blocks are recommended when you want to apply synchronization to a specific section of code within a method, allowing more fine-grained control over synchronization. This can help reduce contention and improve performance in scenarios where synchronization is necessary. Synchronized methods are used when you want to synchronize the entire method for simplicity.
To update UI components from a non-JavaFX thread, use ________.
- Platform.exit()
- Platform.repaint()
- Platform.runLater()
- Platform.update()
To update UI components from a non-JavaFX thread in JavaFX, you should use the Platform.runLater() method. This method allows you to enqueue a Runnable object to be executed on the JavaFX Application Thread, ensuring that UI updates are performed on the correct thread to avoid concurrency issues.
Which searching algorithm requires the data to be sorted to work effectively?
- Binary Search
- Linear Search
- Merge Sort
- Quick Sort
Binary Search is an algorithm that requires the data to be sorted in ascending or descending order for effective searching. It uses the divide and conquer method and is not suitable for unsorted data.
Consider a scenario where you are designing a graphics system that includes different types of shapes (e.g., Circle, Rectangle). How would you decide between using an abstract class and an interface for defining common methods?
- Use a concrete class and use inheritance to define common methods, as concrete classes can directly provide method implementations.
- Use an abstract class with a base shape class and common methods, as abstract classes can provide both method implementations and fields.
- Use an interface to define common methods, as interfaces allow for multiple inheritance and can be implemented by different shape classes.
- Use both an abstract class and an interface, combining the advantages of both.
In this scenario, using an abstract class is appropriate because you can define common methods with default implementations in the base shape class. This provides code reusability and allows shape classes to inherit these methods. Interfaces can also be used, but they don't provide method implementations, making abstract classes a more suitable choice for this use case.
A ________ block will always execute, whether an exception is thrown or not.
- catch
- finally
- throw
- try
The finally block is used to define a block of code that always executes, regardless of whether an exception is thrown or not. It's commonly used for cleanup operations such as closing files or releasing resources.