|
Question: Can you explain the java.util.concurrent package in Java?
|
Answer: The java.util.concurrent package in Java provides utility classes for concurrent programming,
such as thread pools, synchronization primitives, and concurrent data structures.
It aims to simplify concurrent programming and improve performance by providing efficient and
thread-safe alternatives to traditional synchronization mechanisms.
The major components of this package are:
• Executor: Provides a set of interfaces that represents an object whose implementation executes tasks.
• ExecutorService: Provides an interface and only forces the underlying implementation to implement execute() method.
• ScheduledExecutorService: It is similar to ExecutorService but can perform tasks periodically.
• Future: It represents the result of an asynchronous operation.
• CountDownLatch: Provides an utility class that blocks a set of threads until some operations get completed.
• CyclicBarrier: It is similar to CountDownLatch with the excepttion that one can reuse it.
• Semaphore: It is used for blocking thread-level access to some part of the logical or physical resource.
• ThreadFactory: Acts as a thread pool which creates a new thread on demand.
• BlockingQueue: Provides interface to support flow control.
• DelayQueue: Provides Priority Queue to order elements based on their delay time.
• Lock: Provides utility for blocking other threads from accessing a certain segment of code.
• Phaser: Acts as a reusable barrier for threads to wait before the execution continues.
|
|
|
|
|
|
Question: What is the purpose of the 'volatile' keyword in Java concurrency?
|
Answer: The 'volatile' keyword in Java is used to indicate that a variable's value may be changed by multiple
threads simultaneously.
It ensures that any thread reading the variable always gets the latest updated value from memory,
thus providing visibility guarantees in a multi-threaded environment.
|
|
Question: Can you compare the ArrayList and Vector classes in Java?
|
Answer: You can find the comparison below:
• Both ArrayList and Vector are dynamic array implementations in Java.
• ArrayList is not synchronized, meaning it is not thread-safe, whereas Vector is synchronized, making it thread-safe.
• ArrayList is preferred for single-threaded scenarios, while Vector is suitable for multi-threaded scenarios where thread safety is required.
|
|
Question: What is the compareTo() method in Java, and how is it used?
|
Answer: The compareTo() method is used for comparing objects of classes that implement the Comparable interface.
It compares the current object with another object, returning a negative integer, zero, or a positive integer depending on whether the current object is less than, equal to, or greater than the other object, respectively.
|
|
|
|
|
|
Question: What is the purpose of the 'break' and 'continue' statements in Java loops?
|
Answer: You can find the purpose below:
• The break statement is used to terminate the loop immediately and transfer control to the statement following the loop.
• The continue statement is used to skip the rest of the loop's body and proceed to the next iteration of the loop.
|