How does type inference work with Lambda expressions in Java?
- Type inference always uses the Object type for Lambda parameters.
- Type inference automatically infers parameter types from the context and Lambda body.
- Type inference is not applicable to Lambda expressions in Java.
- Type inference relies on explicit type declarations for Lambda parameters.
In Java, Lambda expressions benefit from type inference, which allows the compiler to automatically infer the parameter types from the context and the Lambda body. This feature makes Lambda expressions concise and expressive. It helps reduce the verbosity of code by eliminating the need for explicit type declarations in most cases. Understanding how type inference works with Lambdas is essential for writing clean and readable code when using functional programming techniques in Java.
How does the BufferedOutputStream class work in Java when connected to a file output byte stream?
- It compresses the data before writing it to the file stream to save storage space.
- It encrypts the data to provide security during the write operation.
- It improves I/O performance by reducing the number of write operations to the underlying stream.
- It reads data from the file output stream and stores it in a buffer for later retrieval.
BufferedOutputStream in Java enhances performance by buffering the output data before writing it to the underlying file stream. This reduces the number of write operations and improves efficiency. It doesn't read or compress data; its primary purpose is to optimize data output.
How can we gracefully shutdown an ExecutorService?
- Call shutdown()
- Call shutdown() and then shutdownNow()
- Call shutdownNow() and then shutdown()
- Call stop()
To gracefully shut down an ExecutorService, you should first call the shutdown() method, which initiates an orderly shutdown, allowing previously submitted tasks to execute before terminating. You should not call shutdownNow() before shutdown() because it forcefully attempts to stop all executing tasks. The other options are incorrect for a graceful shutdown.
Imagine you are implementing a system that performs various mathematical operations. How would you use Lambda expressions to define various operations in a clean and efficient way?
- By creating a separate class for each mathematical operation and using the Lambda keyword to instantiate objects of these classes.
- By defining functional interfaces with abstract methods corresponding to each mathematical operation and implementing them using Lambda expressions.
- By using nested Lambda expressions within each other to perform mathematical operations.
- By using traditional method declarations and avoiding Lambda expressions for mathematical operations.
In Java, you can use Lambda expressions to implement functional interfaces with a single abstract method. For mathematical operations, you can define functional interfaces, such as BinaryOperator, and use Lambda expressions to implement these interfaces concisely and efficiently. This approach enhances code readability and allows you to pass behavior as data, making your code more modular.
When reading from a file using a FileReader, it's often wrapped with a ________ to increase efficiency.
- BufferedReader
- FileBufferReader
- FileWriter
- InputStreamReader
When reading from a file, wrapping a FileReader with a BufferedReader is a common practice in Java. BufferedReader buffers the input, reducing the number of reads from the file and thus increasing efficiency.
Which of the following data structures does not allow duplicate elements?
- ArrayList
- HashSet
- LinkedList
- TreeMap
The HashSet data structure in Java does not allow duplicate elements. It is implemented using a hash table and ensures that all elements are unique by using the hashing mechanism. ArrayList and LinkedList can contain duplicate elements, while TreeMap allows duplicates based on keys.
What will be the output of the executeQuery() method in JDBC?
- A boolean indicating success or failure.
- Nothing; it doesn't return any value.
- The number of rows affected.
- The result of the SQL query execution.
The executeQuery() method in JDBC returns a ResultSet object, which contains the result of the SQL query execution. This ResultSet can be used to retrieve and manipulate the query results. The other options are incorrect as they do not accurately describe the output of this method.
The ________ class provides a tunable, flexible thread pool.
- ExecutorService
- Runnable
- Thread
- ThreadPoolExecutor
The ThreadPoolExecutor class in Java provides a tunable, flexible thread pool. It allows you to customize various aspects of thread pool behavior, such as the number of threads and task scheduling.
The ScheduledExecutorService interface extends ________ and provides methods to schedule commands to run after a given delay or to execute periodically.
- Callable
- ExecutorService
- Future
- Runnable
The ScheduledExecutorService interface extends the ExecutorService interface in Java. It provides additional methods for scheduling tasks to run after a specified delay or at regular intervals. This is a useful feature for implementing scheduled tasks or background jobs in applications.
If a class implements two interfaces with default methods having the same signature, the compiler will throw an error unless the class ________ the conflicting method.
- abstracts
- hides
- overrides
- renames
In Java, if a class implements two interfaces with default methods having the same signature, it must provide an implementation for the conflicting method by using the @Override annotation to explicitly indicate that it is intended to override the method. This resolves the conflict and prevents a compilation error. Renaming, hiding, or making it abstract won't resolve the issue.