In a real-world application managing user profiles, how might parameterized constructors be used to quickly initialize user objects with provided details during registration?

  • Parameterized constructors are not used for user profile initialization.
  • Parameterized constructors are used for data retrieval from the database.
  • Parameterized constructors are used to create admin profiles with elevated privileges.
  • Parameterized constructors can accept user details as parameters and create user objects with initialized data during registration.
Parameterized constructors can be utilized in a user profile management system to quickly initialize user objects during the registration process. These constructors accept user details (e.g., username, email, password) as parameters, allowing you to create user objects with pre-populated data, making registration more efficient and straightforward.

Lambda expressions are used primarily to define the implementation of ________ interfaces.

  • Abstract
  • Functional
  • Interface
  • Marker
Lambda expressions in Java are primarily used to define the implementation of functional interfaces. A functional interface is an interface that has only one abstract method. Lambda expressions provide a concise way to implement the single abstract method of such interfaces.

Which of the following expressions will result in a value of true?

  • "Java" == "java"
  • (4 + 6) * 2 == 20
  • 10 != 10
  • 5 > 3
The expression 5 > 3 is true because 5 is indeed greater than 3. The other options are not true: 10 != 10 is false (since 10 is equal to 10), (4 + 6) * 2 == 20 is true (since 10 equals 20), and "Java" == "java" is false because string comparison in Java is case-sensitive.

Which of the following functional interfaces in Java utilizes Lambda expressions?

  • AbstractClass
  • FunctionalInterface
  • Runnable
  • Serializable
The Runnable interface in Java can be implemented using lambda expressions. It's a functional interface with a single abstract method run(). This allows you to use lambda expressions for tasks that can be executed concurrently. Lambda expressions simplify the creation of anonymous classes for such tasks.

What will happen if the superclass method does not exist in the subclass while trying to override it?

  • It will automatically create a new method in the subclass with the same name.
  • It will lead to a compile-time error.
  • It will result in a runtime error.
  • It will use the superclass method without any issue.
In Java, when you try to override a method from a superclass in a subclass, the method in the superclass must exist; otherwise, it will lead to a compile-time error. Java enforces method signature matching during compile-time, so if the method doesn't exist in the superclass, the compiler will not find a method to override in the subclass, resulting in an error.

The ________ method of Throwable class can be used to retrieve the description of an exception.

  • getDescription()
  • getDescriptionText()
  • getExceptionDescription()
  • getMessage()
The getMessage() method of the Throwable class is used to retrieve the description or message associated with an exception. This message provides additional information about the exception, helping developers understand the cause of the error.

Which of the following classes is used to write characters to a file in Java?

  • BufferedReader
  • FileOutputStream
  • FileWriter
  • PrintWriter
The FileWriter class in Java is used to write characters to a file. It provides methods to write character data to a file in a character stream. FileOutputStream is used for writing binary data, PrintWriter is used for formatted text output, and BufferedReader is used for reading character data, not writing.

What happens if no constructor is provided in a Java class?

  • The class cannot be instantiated, and objects of that class cannot be created.
  • Java automatically provides a default no-argument constructor for the class.
  • The class can only be instantiated by other classes in the same package.
  • The class becomes a singleton by default.
a) is correct. If no constructor is provided in a Java class, Java automatically provides a default no-argument constructor. b) is a common misconception; Java only provides a default constructor if you haven't defined any constructors explicitly. c) and d) are incorrect statements.

What is the main disadvantage of the Bubble Sort algorithm in terms of performance?

  • It has a time complexity of O(n^2) in the worst case, making it inefficient for large datasets.
  • It is not a stable sorting algorithm, leading to unpredictable results when sorting objects with equal keys.
  • It is not an in-place sorting algorithm, which means it requires additional memory for sorting.
  • It requires additional memory space to perform sorting, increasing its space complexity.
The main disadvantage of Bubble Sort is its worst-case time complexity of O(n^2), which makes it inefficient for sorting large datasets. It is a comparison-based sorting algorithm, and its performance degrades significantly as the dataset size increases. Its stability and in-place sorting characteristics are not the primary factors affecting its performance.

To access or modify the private fields in a class, you should use ________ methods.

  • accessor
  • constructor
  • mutator
  • public
To access or modify private fields in a class, you should use "mutator" methods, also known as setter methods. These methods are designed to set or modify the private field values, maintaining control over access.