How does Java handle the division of an integer by zero?
- It returns NaN (Not-a-Number).
- It returns a positive or negative infinity value, depending on the sign of the numerator.
- It returns zero.
- It throws an ArithmeticException.
In Java, dividing an integer by zero results in an ArithmeticException being thrown at runtime. Division by zero is mathematically undefined, and Java handles it by throwing this exception to indicate the error. Options 1, 3, and 4 are incorrect because they don't accurately represent how Java handles this situation.
A JDBC ________ provides the necessary methods to interact with the database.
- Connection
- Driver
- ResultSet
- Statement
In JDBC, a Connection is used to establish a connection to a database. It provides the necessary methods to interact with the database, such as executing SQL queries and managing transactions. A JDBC Driver is responsible for establishing the connection, but the Connection object is what allows you to interact with the database.
Imagine you are working on a system that categorizes user feedback into positive, negative, and neutral based on certain keywords. Describe how you'd structure your control statements to efficiently categorize the feedback.
- Create a custom machine learning model
- Implement a decision tree algorithm
- Use if-else statements with keyword checks
- Utilize regular expressions for keyword matching
To efficiently categorize user feedback based on keywords, you can use if-else statements. For each feedback, check if it contains specific positive, negative, or neutral keywords. Regular expressions can also be helpful for more complex matching. While decision trees and machine learning models are powerful for sentiment analysis, they might be overkill for simple keyword-based categorization.
Which of the following access modifiers is allowed for a method in an interface?
- default
- private
- protected
- public
In Java interfaces, all methods are implicitly public, whether you declare them as such or not. You cannot use the private, protected, or default access modifiers for methods in an interface.
The ________ keyword can be used to print multi-dimensional arrays in a deep-to-string manner.
- deepToString
- display
- toString
In Java, the Arrays.deepToString() method can be used to print multi-dimensional arrays in a deep-to-string manner. This method recursively converts the array into a string representation, including nested arrays, making it useful for debugging and displaying complex data structures.
Which loop structure should be used when the number of iterations is known in advance?
- do-while loop
- for loop
- if statement
- while loop
The for loop is ideal when you know the number of iterations in advance. It consists of an initialization, condition, and increment/decrement statement. This loop is suitable for iterating over arrays, collections, or any situation where the number of iterations is predetermined.
What is the primary purpose of a constructor in Java?
- To create objects of the class.
- To define the class methods.
- To initialize the class variables.
- To provide a way to destroy objects of the class.
In Java, a constructor's primary purpose is to initialize the class's instance variables when an object is created. Constructors don't define class methods or create/destroy objects; that's not their primary role.
A ________ block will always execute, whether an exception is thrown or not.
- catch
- finally
- throw
- try
The finally block is used to define a block of code that always executes, regardless of whether an exception is thrown or not. It's commonly used for cleanup operations such as closing files or releasing resources.
The method getInputStream() returns an input stream that reads from the ________.
- URL
- output stream
- remote object
- socket
The getInputStream() method in Java returns an input stream that allows you to read data from the remote object referred to by the URL. This is commonly used in HTTP connections to read the response data from a server. The other options do not represent what this method returns.
Consider a scenario where you are designing a graphics system that includes different types of shapes (e.g., Circle, Rectangle). How would you decide between using an abstract class and an interface for defining common methods?
- Use a concrete class and use inheritance to define common methods, as concrete classes can directly provide method implementations.
- Use an abstract class with a base shape class and common methods, as abstract classes can provide both method implementations and fields.
- Use an interface to define common methods, as interfaces allow for multiple inheritance and can be implemented by different shape classes.
- Use both an abstract class and an interface, combining the advantages of both.
In this scenario, using an abstract class is appropriate because you can define common methods with default implementations in the base shape class. This provides code reusability and allows shape classes to inherit these methods. Interfaces can also be used, but they don't provide method implementations, making abstract classes a more suitable choice for this use case.