Home » Java Quiz » Page 53

The ______ interface is used when you want a task to return a value after execution in a thread.

  • Callable
  • Executable
  • Runnable
  • Threadable
In Java, the Callable interface is used when you want a task to return a value after its execution in a separate thread. It's similar to the Runnable interface but allows for a return value.
Discuss it

Imagine you are developing a real-time multiplayer online game where player data needs to be synchronized. What strategy and technology would you choose for networking communication?

  • Use TCP with WebSockets for reliable and bidirectional communication.
  • Use UDP with WebSockets for low latency and real-time updates.
  • Use TCP with Sockets for simplicity and ease of implementation.
  • Use UDP with Sockets for minimal overhead and high throughput.
For a real-time multiplayer game, a combination of TCP and WebSockets is a robust choice. TCP provides reliability, ensuring that player data is accurately synchronized. WebSockets, built on top of TCP, add bidirectional communication for real-time updates. This approach balances reliability and real-time responsiveness. UDP with WebSockets (Option 2) may sacrifice reliability for low latency, which can lead to data loss. Using just TCP with Sockets (Option 3) may not provide the required real-time capabilities, and UDP with Sockets (Option 4) lacks the reliability needed for game synchronization.
Discuss it

The ________ interface provides methods to retrieve the meta data of the database such as its structure (tables, schemas), the user on the connection, etc.

  • ConnectionMetaData
  • DatabaseMetaData
  • ResultSetMetaData
  • StatementMetaData
The DatabaseMetaData interface in JDBC provides methods for retrieving metadata about the database, including information about its structure (tables, schemas), the user associated with the connection, and more. It's essential for database introspection and querying the database schema. The other options are not used for this purpose.
Discuss it

The class ________ allows an application to write primitive Java data types to an output stream in a portable way.

  • ByteArrayOutputStream
  • DataOutputStream
  • ObjectOutputStream
  • PrintStream
The class ObjectOutputStream in Java is used for writing primitive Java data types to an output stream in a portable way. It provides methods for writing various data types to the stream.
Discuss it

If multiple case labels match the switch expression, then only the ________ matching case will be executed.

  • all
  • first
  • first-matching
  • last
When there are multiple case labels that match the switch expression in Java, only the first-matching case will be executed. Subsequent cases with matching labels will be ignored, ensuring that only the first matching case block is executed.
Discuss it

Considering threading, which collection class might introduce higher overhead in managing read and write access?

  • ArrayList
  • HashSet
  • CopyOnWriteArrayList
  • ConcurrentHashMap
In Java, when considering threading and concurrent access, the CopyOnWriteArrayList can introduce higher overhead in managing read and write access. This is because it creates a new copy of the underlying array every time a modification operation is performed (e.g., add or remove). While this ensures thread safety during iterations, it can be inefficient for scenarios with frequent write operations. So, option (c) is correct, with the explanation that CopyOnWriteArrayList is used for thread-safe iteration but may introduce overhead in write operations.
Discuss it

To retrieve the result of a computation from a Future, you use the ________ method.

  • acquire()
  • fetch()
  • get()
  • obtain()
In Java, to retrieve the result of a computation from a Future object, you use the get() method. The get() method blocks until the computation is complete and then returns the result. This is a fundamental method when working with concurrent programming and asynchronous tasks.
Discuss it

The method read() of FileReader class returns ________ when the end of the file is reached.

  • True
  • -1
  • 0
  • FALSE
The read() method of the FileReader class returns -1 when the end of the file is reached. This indicates that there are no more characters to read from the file.
Discuss it

The class ________ allows an application to read bytes from a file, modifying them, and then writing them back to the file.

  • BufferedWriter
  • FileInputStream
  • FileReader
  • RandomAccessFile
The class RandomAccessFile in Java is used to perform read and write operations on a file. Unlike other file I/O classes, it allows you to modify bytes at specific positions in a file. You can move the file pointer to a desired location using this class and then read or write data from or to that position.
Discuss it

How does Java handle overriding methods that throw exceptions?

  • The overridden method must declare exceptions
  • The overriding method cannot declare exceptions
  • The overriding method may declare exceptions
  • The overriding method must declare exceptions
In Java, when a subclass overrides a method from its superclass, it must adhere to the method signature, including the exceptions it can throw. If the superclass method declares exceptions, the overriding method can declare the same exceptions or subtypes of those exceptions. This rule ensures that the subclass does not throw unexpected exceptions.
Discuss it