Which of the following is the correct way to declare an integer variable in Java?
- float a;
- int a = 5;
- int[] a;
- integer a = 5;
In Java, the int keyword is used to declare an integer variable. The syntax is: int variableName = value;. The other options are not the correct ways to declare a single integer variable.
The method ________ of ServerSocket class is used to listen for incoming client requests.
- accept()
- connect()
- listen()
- open()
In Java, the accept() method of the ServerSocket class is used to listen for incoming client requests. When a client attempts to connect, this method accepts the connection and returns a Socket object for further communication.
What is the outcome of calling the get() method on Future if the task is canceled?
- It returns the result of the task.
- It throws a CancellationException.
- It throws an ExecutionException.
- It throws an InterruptedException.
When you call the get() method on a Future and the associated task is canceled, it throws a CancellationException. This exception indicates that the task was canceled before it could complete. It is important to catch this exception when working with Future objects to handle canceled tasks gracefully.
What does the setScene() method do in JavaFX?
- Sets the background.
- Sets the primary stage.
- Sets the scene for the stage.
- Sets the title.
In JavaFX, the setScene() method is used to set the scene for a Stage. The scene contains the graphical content that you want to display within the stage. By calling setScene(), you associate a specific scene with a stage, allowing you to display different content. The other options are not the purpose of this method.
Which operator is used in Java to compare two string objects for equality?
- !=
- .equals()
- ==
- compare()
In Java, you should use the .equals() method to compare the contents of two string objects for equality. The == operator, on the other hand, checks whether the two string objects are the same object in memory, which is not the same as comparing their content. The other options are not the recommended way to compare strings for equality.
Imagine a scenario in a multi-threaded application where certain resources are being accessed concurrently, leading to data inconsistency. How would you solve this issue using Locks and Conditions?
- Implement resource locking using the volatile keyword to ensure data consistency and use Thread.sleep() for thread synchronization.
- Use ExecutorService to schedule resource access tasks concurrently, as the use of Locks and Conditions is not necessary in this scenario.
- Use ExecutorService to schedule resource access tasks sequentially, ensuring that only one thread accesses the resources at a time.
- Use synchronized blocks to protect access to the shared resources and notify/wait mechanisms from within those blocks to coordinate thread access.
In a multi-threaded scenario where data inconsistency is a concern, you can use Locks and Conditions. Synchronized blocks can be used to protect access to shared resources, and notify/wait mechanisms can be used to coordinate thread access. This ensures that only one thread accesses the resource at a time, preventing data inconsistency.
Which of the following access modifiers allows a member to be accessed from anywhere?
- default (no modifier)
- private
- protected
- public
In Java, the public access modifier allows a member to be accessed from anywhere, including outside the class, package, and even from different packages. It provides the highest level of accessibility. The other options restrict access to varying degrees.
You are developing a game and need to compare whether two objects are in the same location, considering that the location is represented using floating-point values. How do you manage the comparison considering the imprecision of floating-point arithmetic?
- Rely solely on exact comparisons and avoid using floating-point values for location representation.
- Round the floating-point values to a specified number of decimal places before comparison to eliminate imprecision.
- Use epsilon values to define a small tolerance level and compare the objects' positions within that tolerance to account for floating-point imprecision.
- Use integer-based coordinates for location representation to avoid floating-point imprecision altogether.
Floating-point imprecision is a common issue when comparing coordinates in games. To address this, it's best to use epsilon values to define a small tolerance level. This allows for approximate comparisons, accounting for the imprecision inherent in floating-point arithmetic. The other options do not effectively address this issue.
Which keyword is used to implement an interface in Java?
- abstract
- extends
- implements
- interface
In Java, the implements keyword is used to implement an interface. When a class implements an interface, it must provide concrete implementations for all the methods declared in that interface. The other options (extends, interface, abstract) are used for different purposes and are not used to implement interfaces.
Can a subclass constructor directly access the private variables of its superclass?
- No
- Only if they are static
- Only if they have the same name
- Yes
No, a subclass constructor cannot directly access the private variables of its superclass. Private variables are not visible to subclasses, so they cannot be accessed or modified directly. Instead, you can use setter and getter methods or make the superclass variables protected or package-private (default) if you need subclass access.