Which array method removes the first element from an array and returns that removed element?
- shift()
- unshift()
- pop()
- push()
The array method that removes the first element from an array and returns that removed element is shift(). It shifts all other elements to a lower index, effectively removing the first element. The unshift() method adds elements to the beginning, pop() removes the last element, and push() adds elements to the end of the array.
The problem of multiple nested callbacks in JavaScript is commonly referred to as ________.
- callback hell
- nested loop
- async overload
- function maze
The problem of multiple nested callbacks in JavaScript is commonly referred to as "callback hell." It occurs when callback functions are heavily nested, making the code hard to read and maintain. This can lead to readability and maintenance issues.
Which of the following methods mutates the original array?
- map()
- filter()
- concat()
- reduce()
The concat() method is used to concatenate two or more arrays and returns a new array. It does not mutate the original array. In contrast, methods like map(), filter(), and reduce() can modify the original array, so they should be used with caution.
Which type of event listener will not get removed by the removeEventListener method?
- Inline event listeners
- Anonymous event listeners
- Named function event listeners
- Arrow function event listeners
Event listeners added using named functions can be removed with the removeEventListener method because they are given a reference to the function. In contrast, inline event listeners, anonymous functions, and arrow functions are not easily removed because they lack a reference. This makes them more challenging to manage and clean up in your code.
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.