Which method is used to start the execution of a thread?

  • begin()
  • runThread()
  • start()
  • startThread()
To start the execution of a thread in Java, you should call the start() method on a Thread object. This method internally calls the run() method, which contains the code to be executed by the thread. The other options do not start a thread in the correct way.

Which class is commonly used to create a simple animation that moves a node along a path in JavaFX?

  • Animation
  • NodeMoveAnimation
  • PathTransition
  • Scene
In JavaFX, the PathTransition class is commonly used to create animations that move a node along a path. This class allows you to specify the path, duration, and other animation properties. The other options, like Scene, are used for different aspects of JavaFX applications.

Which of the following is synchronized?

  • ArrayList
  • Hashtable
  • LinkedList
  • StringBuilder
The Hashtable class in Java is synchronized, which means it is thread-safe. This ensures that multiple threads can safely access and modify the Hashtable concurrently without causing data corruption. ArrayList and LinkedList are not synchronized, making them suitable for single-threaded operations by default. StringBuilder is also not synchronized and is used for efficient string manipulation in a single thread.

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."

If a superclass has a protected field, will subclasses in different packages have direct access to it?

  • Access to protected fields depends on the specific package-level access rules defined in the project.
  • No, subclasses in different packages cannot access the protected field directly; they must use getter and setter methods.
  • Subclasses can access protected fields, but only if they are in the same package as the superclass.
  • Yes, subclasses in different packages can access the protected field directly without any restrictions.
Subclasses in different packages cannot access the protected field directly. Protected members are accessible to subclasses, but only within the same package or through inheritance. Access control rules apply to protect the encapsulation of classes across packages, ensuring proper access control and encapsulation.

In a Java program, you can't use an object until it has been _______.

  • assigned
  • declared
  • imported
  • initialized
In a Java program, you can't use an object until it has been initialized. This means that an object must go through its constructor to set its initial state before you can use its methods or access its fields. Declaring or importing an object is not sufficient; it must be properly initialized.

What is the primary benefit of using Lambda expressions in Java?

  • They allow you to declare variables with multiple data types.
  • They enable you to create global variables.
  • They improve the performance of the Java program.
  • They provide a shorter syntax for writing methods.
Lambda expressions in Java primarily offer a more concise and expressive way to write methods, especially for implementing functional interfaces. This concise syntax reduces boilerplate code, making the codebase more readable and maintainable. This is a key feature of Java's functional programming capabilities.