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.
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.
Which of the following is true regarding the flow of control in a try-catch-finally statement?
- The catch block is executed before finally.
- The catch block is optional.
- The code inside try is optional.
- The finally block is executed before try.
In a try-catch-finally statement in Java, the flow of control is such that the try block is executed first. If an exception occurs within the try block, control is transferred to the appropriate catch block (if matching). Finally block is executed after try (whether an exception occurred or not), making it suitable for cleanup code.
In a switch case, the ________ keyword is used to specify the code that should be executed if no case matches.
- default
- defaultcase
- else
- fallback
In a switch case in Java, the default keyword is used to specify the code that should be executed if none of the case labels match the switch expression. It acts as a fallback or default option when no other case matches the switch expression.
Which Java method is used to establish a connection to a specified URL?
- URLConnect()
- connectToURL()
- establishConnection()
- openConnection()
To establish a connection to a specified URL in Java, you use the openConnection() method provided by the URL class. This method returns a URLConnection object, which can be used to interact with the resource located at the URL.
What will be the output of the following code snippet: System.out.println("Java".concat("Programming"))?
- Compilation Error
- Java Programming
- JavaProgramming
- ProgrammingJava
The concat() method in Java combines two strings, and in this case, it appends "Programming" to "Java," resulting in "JavaProgramming." Therefore, the correct output is "JavaProgramming."
What is the primary purpose of using synchronized methods in Java?
- To ensure that a method is only accessible within the same package.
- To make a method private and inaccessible.
- To optimize the execution speed of a method.
- To prevent multiple threads from accessing and modifying shared resources simultaneously.
Synchronized methods in Java are used primarily to prevent multiple threads from accessing and modifying shared resources simultaneously, ensuring thread safety. This is crucial in multithreading scenarios where multiple threads may otherwise interfere with each other when accessing shared data.