Using the ________ method, you can run multiple SQL statements using a single Statement object, separated by semicolons.

  • execute()
  • executeBatch()
  • executeQuery()
  • executeUpdate()
The executeBatch() method in JDBC allows you to execute multiple SQL statements using a single Statement object, with statements separated by semicolons. This is particularly useful for batch processing. Other options are valid for executing single SQL statements.

You are working on a class that must not be instantiated and only serves to provide utility static methods. How would you utilize constructors to enforce this non-instantiability?

  • Define a constructor with a boolean parameter to control instantiation.
  • Define a private constructor to prevent instantiation and make the class final to prevent subclassing.
  • Make the class abstract with a default constructor for utility methods.
  • Utilize a public constructor with a warning message to discourage instantiation.
To enforce non-instantiability of a class meant for utility static methods, you should define a private constructor, preventing external instantiation. Additionally, making the class final ensures that it cannot be subclassed, further enforcing its intended usage as a utility class with only static methods.

How can you prematurely exit a loop in Java?

  • break statement
  • continue statement
  • goto statement (not recommended)
  • return statement
You can use the break statement to prematurely exit a loop in Java. When break is encountered within a loop, it immediately terminates the loop's execution, allowing you to exit the loop based on a certain condition or event. It is a commonly used control flow statement for loop termination.

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.

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.

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 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.

To retrieve the value of the first column in the current row of a ResultSet, you can use the method ________.

  • getFirstColumnValue()
  • getInt(0)
  • getRowValue()
  • getString(1)
To retrieve the value of the first column in the current row of a ResultSet, you can use the method getString(1). This method fetches the value of the column at index 1 (the first column) and returns it as a string. The other options are not valid methods for this purpose.

How are Lambda expressions compiled in Java?

  • Lambdas are compiled into native machine code for better performance.
  • Lambdas are compiled into traditional anonymous inner classes.
  • Lambdas are not compiled; they are interpreted at runtime.
  • Lambdas are pre-compiled and stored as bytecode in a separate file.
In Java, Lambda expressions are compiled into traditional anonymous inner classes by the Java compiler. These inner classes capture the behavior defined by the Lambda expression. The use of inner classes allows the Java Virtual Machine (JVM) to treat Lambdas as objects with associated methods, which makes them compatible with existing Java features and enables the use of functional interfaces. Understanding this compilation process is crucial for developers who want to understand the inner workings of Lambdas and their impact on the bytecode.

Consider a scenario where you need to enforce singleton behavior on a class. How would constructors play a role in ensuring this?

  • Constructors are used to create multiple instances, each with a unique ID.
  • Constructors are used to enforce thread safety in the singleton pattern.
  • Constructors ensure single instance creation by marking the constructor as private and providing a static method to retrieve the instance.
  • Constructors play no role in enforcing singleton behavior.
In the singleton pattern, constructors play a crucial role in enforcing the creation of a single instance of a class. To achieve this, the constructor is marked as private to prevent external instantiation, and a static method is provided to retrieve the single instance. This ensures that only one instance of the class exists throughout the application's lifecycle.

Which method is used to read a single character from a character input stream in Java?

  • read()
  • readChar()
  • readCharacter()
  • readLine()
The read() method in Java's character input stream classes is used to read a single character at a time. It returns an integer representing the Unicode code point of the character read. The other options are not valid methods for reading a single character from a character input stream.

The showAndWait() method is used to display a ________ and wait for the user's response.

  • Alert
  • Dialog
  • Notification
  • Popup
In JavaFX, the Alert class is often used to display dialog boxes that require user interaction. The showAndWait() method is used to display an alert dialog and wait for the user's response before proceeding. The other options, Dialog, Popup, and Notification, are not the classes commonly associated with this method.