If a superclass method does not throw an exception, can the overridden method in the subclass throw an exception?
- No, it cannot throw any exception
- No, it cannot throw any exception
- Yes, it can throw any exception
- Yes, it can throw any exception
In Java, if a superclass method does not declare any exceptions, the overridden method in the subclass cannot throw checked exceptions that are broader in scope than those of the superclass method. This rule is in place to ensure that the subclass does not introduce unexpected exceptions.
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.
How can you manipulate request headers when using HttpURLConnection?
- By altering the HTTP request method
- By calling addRequestHeader method
- By modifying the Content-Type header
- By using the setRequestProperty method
To manipulate request headers in HttpURLConnection, you should use the setRequestProperty method. This method allows you to set custom headers for your HTTP request. Modifying the Content-Type header is one specific use case of this method. The other options are not standard ways to manipulate headers using HttpURLConnection.
Which of the following is not a valid JDBC transaction isolation level?
- TRANSACTION_COMMITTED
- TRANSACTION_NONE
- TRANSACTION_REPEATABLE_READ
- TRANSACTION_SERIALIZABLE
JDBC defines standard transaction isolation levels such as TRANSACTION_NONE, TRANSACTION_SERIALIZABLE, and TRANSACTION_REPEATABLE_READ. However, TRANSACTION_COMMITTED is not a valid JDBC transaction isolation level. Isolation levels determine how transactions interact with each other and the data.
Which method removes the first occurrence of the specified element from a LinkedList?
- delete()
- deleteFirst()
- remove()
- removeFirst()
The remove() method in a LinkedList is used to remove the first occurrence of the specified element. It takes the element as an argument and searches for its first occurrence, then removes it. removeFirst() is not a standard method in LinkedList. deleteFirst() and delete() are not valid methods for removing elements in a LinkedList.