What is the purpose of using getters and setters in Java?
- To access and modify the private attributes
- To create objects
- To declare variables
- To perform mathematical operations
Getters and setters are used to access and modify the private attributes (variables) of a class. They help in achieving encapsulation by providing controlled access to the class's internal state. Getters allow reading the value, and setters allow modifying it while enforcing rules and validation.
Which method is used to properly stop a JavaFX application?
- Application.stop();
- Platform.exit();
- System.exit(0);
- stage.close();
To properly stop a JavaFX application, the Application.stop() method should be used. This method is automatically called when the JavaFX application is exiting. It provides a clean way to release resources, close windows, and perform any necessary cleanup operations before the application terminates. Using System.exit(0) or closing the stage directly may not handle cleanup tasks properly.
In Java, if a class implements an interface and does not provide implementations for all its methods, it must be declared as ________.
- Abstract Class
- Concrete Class
- Final Class
- Static Class
When a class in Java implements an interface but doesn't provide implementations for all the interface methods, it must be declared as an abstract class. This is because an abstract class can have unimplemented methods, while concrete classes need to provide implementations for all interface methods they inherit.
The keyword ________ is used to skip the rest of the current loop iteration.
- break
- continue
- exit
- return
In Java, the continue keyword is used to skip the rest of the current loop iteration and move to the next iteration. It is often used in loops like for and while when certain conditions are met, and you want to skip the current iteration and continue with the next one. The other options do not serve this purpose.
The relational operators are often used inside the ______ statement to produce boolean value.
- for
- if
- switch
- while
Relational operators (e.g., <, >, ==) are commonly used inside the "if" statement to create conditions that produce boolean (true/false) values based on comparisons.
What will happen if the DriverManager is unable to connect to the database using the provided URL?
- A compilation error will occur
- A runtime exception will be thrown
- An SQLException will be thrown
- It will silently retry to connect in the background
When the DriverManager in JDBC fails to connect to the database using the provided URL, it throws an SQLException. This exception should be handled in your code to gracefully manage the failure and take appropriate actions, such as logging the error or providing a user-friendly message.
Which of the following character stream classes should be used to read characters, arrays, and lines efficiently?
- BufferedReader
- CharArrayReader
- FileReader
- InputStreamReader
The BufferedReader class is used to read characters, arrays, and lines efficiently from a character input stream. It provides buffering, which makes reading more efficient. FileReader is used to read characters from files, and InputStreamReader is used for byte-to-character conversion. CharArrayReader is used to read from character arrays.
When using a single-thread executor, what happens if a submitted task throws an exception?
- The exception is caught, logged, and the executor continues to execute other tasks.
- The exception is ignored, and the executor continues to execute other tasks.
- The exception is propagated up the call stack to the caller of the submit() method.
- The thread running the task is terminated, and the executor replaces it with a new thread.
In a single-thread executor, when a submitted task throws an exception, it is caught and logged, but the executor continues to execute other tasks. The executor does not terminate due to an exception in a single task; it maintains the single thread for execution.
Imagine you are developing a networking application that establishes a connection to various servers. How would you handle various types of I/O exceptions, ensuring that your application can fail gracefully and retry connecting to the server without impacting the user experience?
- Handle all I/O exceptions with a single generic catch block. Retry connecting to the server immediately after an exception occurs without any delay.
- Implement a single global catch block to handle all I/O exceptions and use a fixed retry interval for connecting to the server. Display a generic message to the user on repeated failures.
- Use a combination of try-catch blocks to handle specific I/O exceptions like SocketTimeoutException and IOException. Implement retry logic with exponential backoff to retry connecting to the server. Maintain a counter to limit the number of retries.
- Use a dedicated library or framework for handling networking connections and exceptions. Configure the library to handle I/O exceptions and retry logic automatically. Display user-friendly messages and provide options for users to retry or cancel the operation.
In a networking application, it's crucial to handle I/O exceptions gracefully. Option 1 recommends using specific try-catch blocks for different exception types, which allows for fine-grained error handling and implementing retry logic with backoff. Option 2 suggests an immediate retry without any delay, which can lead to repeated failures. Options 3 and 4 propose more generic approaches, which may not provide the same level of control and user-friendly handling.
________ allows you to traverse the collection, access the element, and insert
- Buffer
- Enumeration
- Iterator
- Stream
The Iterator interface in Java allows you to traverse a collection, access elements, and insert elements in the middle of traversal using the remove() and add() methods. The other options do not provide this functionality.