Tag: java

To answer this question, let's break down each option:

Option A) After object B is notified, or after two seconds Option B) After the lock on B is released, or after two seconds Option C) Two seconds after object B is notified Option D) Two seconds after lock B is released

The correct answer is A) After object B is notified, or after two seconds.

Explanation: When the wait(2000) method is called on an object, it causes the current thread to release the lock on that object and enter a waiting state. The thread will remain in the waiting state until one of two conditions is met:

1. The object is notified by another thread using the notify() or notifyAll() method.
2. The specified time (2000 milliseconds in this case) has elapsed.

In this scenario, thread A will become a candidate to get another turn at the CPU either when object B is notified or after two seconds, whichever comes first. So option A is correct.

Option B is incorrect because the thread does not need to wait for the lock on object B to be released. The wait(2000) method already releases the lock.

Option C is incorrect because the thread does not wait for two seconds after object B is notified. It can become a candidate to get another turn at the CPU immediately after being notified.

Option D is incorrect because the thread does not wait for two seconds after releasing the lock on object B. It can become a candidate to get another turn at the CPU immediately after releasing the lock.

Therefore, the correct answer is A) After object B is notified, or after two seconds.

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To answer this question, let's analyze the given code step by step:

TreeSet map = new TreeSet();
map.add("one");
map.add("two");
map.add("three");
map.add("four");
map.add("one");
Iterator it = map.iterator();
while (it.hasNext()) {
    System.out.print(it.next() + " ");
}

In this code, a TreeSet named map is created. A TreeSet is a collection that stores elements in a sorted and unique order.

The following elements are added to the map:

• "one"
• "two"
• "three"
• "four"
• "one" (Note that "one" is added again)

Next, an iterator named it is created using the iterator() method of the TreeSet. The iterator allows iterating over the elements in the TreeSet in a sequential manner.

The while loop is then used to iterate over the elements in the TreeSet using the iterator. The condition it.hasNext() checks if there are more elements to iterate over. If there are, the loop continues.

Inside the loop, it.next() is used to retrieve the next element from the TreeSet. This element is then printed using System.out.print().

Let's analyze the output of the code:

• The elements in the TreeSet are stored in a sorted order.
• Since "four" comes before "one" in alphabetical order, "four" is printed first.
• Next, "one" is printed.
• "three" comes before "two" in alphabetical order, so "three" is printed next.
• Finally, "two" is printed.

Therefore, the output of the code is: "four one three two".

The correct answer is D. "four one three two".

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To answer this question, you need to understand the concept of coupling in software engineering. Coupling refers to the degree of interdependence between modules or components in a system. Low coupling means that the modules or components are loosely connected and have minimal dependencies on each other.

Let's go through each option to understand why it is correct or incorrect:

Option A) The attributes of the class are all private - This option does not indicate low coupling. The visibility of attributes does not necessarily determine the level of coupling.

Option B) The class refers to a small number of other objects - This option indicates low coupling. When a class refers to a small number of other objects, it suggests that it has minimal dependencies on other components.

Option C) The object contains only a small number of variables - This option does not directly indicate low coupling. The number of variables in an object does not necessarily determine the level of coupling.

Option D) The object is referred to using an anonymous variable, not directly - This option does not indicate low coupling. The way an object is referred to does not directly affect the level of coupling.

Option E) The reference variable is declared for an interface type, not a class. The interface provides a small number of methods - This option indicates low coupling. Declaring a reference variable for an interface type and having the interface provide a small number of methods suggests loose coupling between the components.

The correct answer is Option E. This option is correct because it indicates a situation with low coupling, where the reference variable is declared for an interface type, and the interface provides a small number of methods.

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To answer this question, we need to understand the key components and architecture of a J2EE (Java 2 Enterprise Edition) application.

Option A) "must be created via a Java IDE" - This option is incorrect because J2EE applications can be developed using any text editor or Integrated Development Environment (IDE) that supports Java development. While a Java IDE can provide features and tools to streamline the development process, it is not a requirement for creating J2EE applications.

Option B) "can run on different machines, but only with the same Operating System" - This option is incorrect because J2EE applications are designed to be platform-independent. They can run on different machines with different operating systems as long as the Java Virtual Machine (JVM) is installed on the target machine. This allows the J2EE application to be deployed and run on various platforms, such as Windows, Linux, or macOS.

Option C) "are typically based on Servlets, JSPs, and Enterprise Java Beans" - This option is correct because J2EE applications are commonly built using a combination of Servlets, JavaServer Pages (JSPs), and Enterprise Java Beans (EJBs). Servlets handle the request-response cycle, JSPs provide the presentation layer, and EJBs handle the business logic and data persistence.

Option D) "need no runtime environment" - This option is incorrect because J2EE applications require a runtime environment to execute. The J2EE runtime environment, also known as an application server or container, provides the necessary infrastructure and services for the application to run, such as managing components, handling transactions, and providing security.

Therefore, the correct answer is C) J2EE applications are typically based on Servlets, JSPs, and Enterprise Java Beans. These components work together to create a scalable and robust architecture for building enterprise-level applications.

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• Wrong explanation