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.
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.
Which of the following character stream classes should be used to read characters, arrays, and lines efficiently?
- BufferedReader
- CharArrayReader
- FileReader
- InputStreamReader
The BufferedReader class is used to read characters, arrays, and lines efficiently from a character input stream. It provides buffering, which makes reading more efficient. FileReader is used to read characters from files, and InputStreamReader is used for byte-to-character conversion. CharArrayReader is used to read from character arrays.
When using a single-thread executor, what happens if a submitted task throws an exception?
- The exception is caught, logged, and the executor continues to execute other tasks.
- The exception is ignored, and the executor continues to execute other tasks.
- The exception is propagated up the call stack to the caller of the submit() method.
- The thread running the task is terminated, and the executor replaces it with a new thread.
In a single-thread executor, when a submitted task throws an exception, it is caught and logged, but the executor continues to execute other tasks. The executor does not terminate due to an exception in a single task; it maintains the single thread for execution.
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.
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.
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 will happen if an exception is not caught by any catch block?
- The exception will be automatically caught by the JVM.
- The program will continue to execute normally.
- The program will enter an infinite loop.
- The program will terminate with an error.
In Java, if an exception is not caught by any catch block within the current method, it will propagate up the call stack, and if not caught anywhere, it will lead to program termination with an error message. This is essential for identifying and handling exceptional situations in a program.
Which class is primarily used for implementing UDP sockets?
- DatagramPacket
- DatagramSocket
- ServerSocket
- Socket
In Java, the DatagramSocket class is primarily used for implementing UDP (User Datagram Protocol) sockets. It provides methods to send and receive UDP packets. The other options are not specific to UDP sockets.
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.