What will happen if the DriverManager is unable to connect to the database using the provided URL?
- A compilation error will occur
- A runtime exception will be thrown
- An SQLException will be thrown
- It will silently retry to connect in the background
When the DriverManager in JDBC fails to connect to the database using the provided URL, it throws an SQLException. This exception should be handled in your code to gracefully manage the failure and take appropriate actions, such as logging the error or providing a user-friendly message.
The relational operators are often used inside the ______ statement to produce boolean value.
- for
- if
- switch
- while
Relational operators (e.g., <, >, ==) are commonly used inside the "if" statement to create conditions that produce boolean (true/false) values based on comparisons.
The keyword ________ is used to skip the rest of the current loop iteration.
- break
- continue
- exit
- return
In Java, the continue keyword is used to skip the rest of the current loop iteration and move to the next iteration. It is often used in loops like for and while when certain conditions are met, and you want to skip the current iteration and continue with the next one. The other options do not serve this purpose.
In Java, if a class implements an interface and does not provide implementations for all its methods, it must be declared as ________.
- Abstract Class
- Concrete Class
- Final Class
- Static Class
When a class in Java implements an interface but doesn't provide implementations for all the interface methods, it must be declared as an abstract class. This is because an abstract class can have unimplemented methods, while concrete classes need to provide implementations for all interface methods they inherit.
A thread that goes into the ________ state will not be brought back to the running state when its sleep time has elapsed or its operation is complete.
- blocked
- sleeping
- terminated
- waiting
Once a thread enters the "terminated" state, it cannot be brought back to the running state. The thread has completed its execution or has been explicitly terminated and cannot be resumed.
What happens to the result of a relational operation if both operands are NaN?
- It returns false.
- It returns true.
- It throws a NaNException.
- It throws a NullPointerException.
When both operands of a relational operation are NaN, Java returns false. This behavior is consistent with the IEEE 754 floating-point standard, which defines the behavior of floating-point numbers, including NaN. Options 2, 3, and 4 are incorrect because they don't reflect the actual behavior of Java in this situation.
The process of instantiating a class and creating an object is also known as _______.
- Abstraction
- Declaration
- Inheritance
- Instantiation
The process of instantiating a class and creating an object is known as "Instantiation." When you instantiate a class, you create an object of that class, which can then be used to access its members.
________ allows you to traverse the collection, access the element, and insert
- Buffer
- Enumeration
- Iterator
- Stream
The Iterator interface in Java allows you to traverse a collection, access elements, and insert elements in the middle of traversal using the remove() and add() methods. The other options do not provide this functionality.
Imagine you are developing a networking application that establishes a connection to various servers. How would you handle various types of I/O exceptions, ensuring that your application can fail gracefully and retry connecting to the server without impacting the user experience?
- Handle all I/O exceptions with a single generic catch block. Retry connecting to the server immediately after an exception occurs without any delay.
- Implement a single global catch block to handle all I/O exceptions and use a fixed retry interval for connecting to the server. Display a generic message to the user on repeated failures.
- Use a combination of try-catch blocks to handle specific I/O exceptions like SocketTimeoutException and IOException. Implement retry logic with exponential backoff to retry connecting to the server. Maintain a counter to limit the number of retries.
- Use a dedicated library or framework for handling networking connections and exceptions. Configure the library to handle I/O exceptions and retry logic automatically. Display user-friendly messages and provide options for users to retry or cancel the operation.
In a networking application, it's crucial to handle I/O exceptions gracefully. Option 1 recommends using specific try-catch blocks for different exception types, which allows for fine-grained error handling and implementing retry logic with backoff. Option 2 suggests an immediate retry without any delay, which can lead to repeated failures. Options 3 and 4 propose more generic approaches, which may not provide the same level of control and user-friendly handling.
Using ________, we can perform cleanup operations when the stream is closed.
- catch
- close
- finally
- try
In Java's Stream API, the close() method is used to perform cleanup operations when the stream is closed. This can be helpful when you need to release external resources or perform any necessary cleanup before the stream is no longer in use.
How does the linear search algorithm find the target value in its input?
- It divides the array into two halves and checks each half separately
- It jumps to a random location and checks if the element is present there
- It starts from the first element and compares each element one by one
- It uses a mathematical formula to calculate the position of the target element
The linear search algorithm finds the target value by starting from the first element of the array and comparing each element one by one until it either finds a match or reaches the end of the array. It is a straightforward and sequential search method, which means it has a worst-case time complexity of O(n), where 'n' is the number of elements in the array.
What is the result of Double.POSITIVE_INFINITY == Double.POSITIVE_INFINITY in Java?
- It depends on the context of the comparison.
- It returns false.
- It returns true.
- It throws an ArithmeticException.
In Java, comparing Double.POSITIVE_INFINITY to itself using the == operator returns true. This behavior is consistent with the IEEE 754 standard, which defines the behavior of floating-point numbers. Double.POSITIVE_INFINITY is considered equal to itself. Options 2 and 3 are incorrect because they don't accurately represent the result of this comparison. Option 4 is incorrect because the comparison of infinity values is well-defined in Java.