How does Java's try-with-resources statement, introduced in Java 7, enhance exception handling?
- It allows you to catch and handle exceptions thrown by resources automatically.
- It allows you to catch multiple exceptions in one catch block.
- It prevents the execution of the finally block.
- It replaces the traditional try-catch block entirely.
Java's try-with-resources statement enhances exception handling by automatically closing resources (e.g., files, streams) after their scope, and if any exceptions are thrown during resource management, they are caught and handled automatically, simplifying resource cleanup.
What will be the output of the following code snippet: System.out.println("2" + "3");?
- "23"
- "5"
- 5
- Error
In the given code snippet, the + operator is used to concatenate two string literals: "2" and "3." Therefore, the output will be the concatenation of these two strings, which is "23." It's important to note that when the + operator is used with strings, it performs string concatenation, not arithmetic addition.
Consider a scenario where you want to evaluate multiple conditions and execute a block of code when at least one of the conditions is true. Which of the following control structures is the most appropriate?
- do...while loop
- for loop
- if...else if ladder
- while loop
In Java, when you need to evaluate multiple conditions and execute a block of code when at least one condition is true, the most appropriate control structure is the if...else if ladder. This structure allows you to test multiple conditions in sequence and execute the block associated with the first true condition. It's commonly used for handling multiple mutually exclusive cases.
The enhanced for loop (or for-each loop) is also known as the ________ loop.
- Enhanced Loop
- For Loop
- For-Each Loop
- Iteration Loop
The enhanced for loop in Java is often referred to as the "for-each" loop because it iterates through each element of an array or collection, making it a convenient way to loop through elements without explicitly defining an index. Options 1 to 3 are incorrect terms for describing this loop.
______ is an example of an explicit lock in Java.
- CountDownLatch
- ReentrantLock
- Semaphore
- Synchronized
ReentrantLock is an example of an explicit lock in Java. It provides a more flexible and fine-grained way to manage locks compared to the built-in synchronized keyword. It allows for features like reentrant locking and fairness policies, making it suitable for complex synchronization scenarios. The Synchronized keyword is also used for locking, but it is implicit and less flexible. The other options are not examples of explicit locks.
Which interface provides methods to check if the computation is complete, wait for its completion, and retrieve the result of the computation?
- CompletionService
- Executor
- Future
- RunnableFuture
The Future interface in Java provides methods to check if a computation is complete, to wait for its completion, and to retrieve the result of the computation. It is commonly used in concurrent programming to manage asynchronous tasks and obtain results when they become available. Executor is not an interface for managing results, and the other options do not provide these specific methods.
The Platform.runLater() method schedules tasks on the ________.
- Background Thread
- JavaFX Thread
- Main Application Thread
- UI Thread
The Platform.runLater() method schedules tasks to be executed on the Main Application Thread in JavaFX. This is important because UI components should only be updated from the UI thread to maintain thread safety and avoid potential issues.
What is the primary purpose of using Callable in Java?
- To create an instance of a Runnable interface
- To create threads that run a specific task
- To define and execute a periodic task
- To run tasks asynchronously and return a result
The primary purpose of using the Callable interface in Java is to run tasks asynchronously and return a result. Unlike the Runnable interface, Callable tasks can return a result or throw an exception. This is commonly used with the Executor framework for managing concurrent tasks that require results.
In JDBC, the ________ provides methods to move to the first record, last record, next record, and previous record in a ResultSet.
- ResultIterator
- ResultSet
- ResultSetMetadata
- ResultSetNavigation
In JDBC, the ResultSet interface provides methods like first(), last(), next(), and previous() to navigate through the result set obtained from a database query. The other options are not related to ResultSet navigation in JDBC.
Which JavaFX class is used to create a pause in your animation, without using a separate thread?
- AnimationTimer
- PauseTransition
- Thread
- Timeline
To create a pause in your animation without using a separate thread, you can use the PauseTransition class in JavaFX. It allows you to add a pause between animations or transitions. The other options are not intended for creating animation pauses without separate threads.