In method overriding, the return type must be the same or a ________ of the superclass overridden method's return type.
- child
- different
- subclass
- superclass
In Java, when you override a method, the return type of the overriding method must be the same as or a subclass of the return type of the overridden method in the superclass. This is known as covariant return types.
Which sorting algorithm uses a divide-and-conquer strategy to sort data?
- Bubble Sort
- Insertion Sort
- Merge Sort
- Selection Sort
Merge Sort is a sorting algorithm that uses a divide-and-conquer strategy. It divides the unsorted list into smaller sublists, sorts those sublists, and then merges them to obtain the final sorted list. This approach results in better performance compared to some other sorting algorithms.
You're developing a game using JavaFX where players interact with multiple animated objects on the screen. How would you efficiently manage and handle multiple events generated by user interactions without causing performance issues?
- Attach event listeners to each individual object to ensure specific actions are taken for each object's interactions.
- Increase the frame rate to ensure that events are processed faster, thus avoiding performance issues.
- Use a single event handler for all objects and manually check which object triggered the event.
- Use event delegation to handle events at a higher-level parent node, reducing the number of event listeners attached to individual objects.
In JavaFX, managing multiple events efficiently is crucial for performance. Using event delegation by handling events at a higher-level parent node minimizes the number of event listeners, reducing overhead. This is a common best practice in JavaFX game development. Increasing the frame rate alone won't solve performance issues and may lead to excessive resource consumption. Using a single event handler is less efficient than event delegation, and attaching listeners to each object increases overhead.
Which of the following loops will always execute its code block at least once?
- do-while loop
- for loop
- if statement
- while loop
The do-while loop is designed to execute its code block at least once, as it checks the condition after executing the loop body. This is useful when you want to ensure that a piece of code runs before checking the condition for termination.
The method ________ of FileOutputStream class is used to write a specific byte of data to a file output stream.
- append
- write
- writeByte
- writeData
The write method of the FileOutputStream class is used to write a specific byte of data to a file output stream. You can use this method to write individual bytes or byte arrays to a file.
What is the default constructor in Java?
- A constructor provided by Java for every class
- A constructor with a single parameter
- A constructor with default values
- A constructor with no parameters
In Java, the default constructor is a constructor provided by Java for every class that doesn't explicitly define its own constructor. It takes no parameters and initializes instance variables to their default values. The other options do not accurately describe the default constructor in Java.
Imagine a scenario where you are developing a library, and you want to restrict the usage of some specific methods to the external world but allow them to be used inside the package. How would you implement this using access modifiers?
- package-private
- private
- protected
- public
To restrict the usage of certain methods to the external world while allowing them to be used within the package, you would use the package-private access modifier. This is achieved by not specifying any access modifier (default) before the method declaration. Public methods are accessible from anywhere, private methods are restricted to the class, and protected methods allow access within the package and subclasses.
Why does Java not support operator overloading?
- Because it's not feasible to implement
- To avoid ambiguity in code
- To promote method overloading instead
- To simplify the language and reduce complexity
Java does not support operator overloading primarily to simplify the language and reduce complexity. Operator overloading can lead to ambiguity in code, making it harder to read and maintain. Instead, Java encourages method overloading as a way to achieve similar functionality.
________ collection classes store objects, whereas ________ collection classes store primitive data types.
- ArrayList / LinkedList
- HashMap / HashSet
- Vector / Hashtable
- Wrapper / Primitive
Wrapper collection classes (such as ArrayList) store objects, while Primitive collection classes (such as ArrayList) store primitive data types directly. The wrapper classes allow primitive data types to be used in collections that require objects.
What will happen if you try to assign a value larger than the maximum value of the byte data type to a byte variable?
- A compilation error will occur because it's not possible to assign a larger value.
- An exception will be thrown at runtime.
- The byte variable will automatically promote to a larger data type to accommodate the value.
- The value will be truncated to fit within the range of the byte data type.
In Java, if you try to assign a value larger than the maximum value (127) of the byte data type to a byte variable, the value will be truncated, and the least significant bits will be retained. This is known as "overflow." The other options do not accurately describe the behavior of byte variables.