Consider a scenario where you want to invert the sign of a numeric value only if a particular boolean condition is true. How can unary operators be utilized to achieve this without using an if statement?
- int invertedValue = (condition) ? -numericValue : numericValue;
- int invertedValue = (condition) ? numericValue : -numericValue;
- int invertedValue = -numericValue;
- int invertedValue = numericValue;
You can use the conditional (ternary) operator ? : to achieve this. If the condition is true, it negates the numericValue by using the unary minus operator. If false, it leaves the numericValue unchanged. Option 1 demonstrates this technique.
How can you securely serialize and deserialize objects to protect sensitive information during the process?
- Define custom serialization and deserialization logic with encryption and authentication mechanisms
- Employ access modifiers such as private and protected for fields and methods
- Ensure that classes are marked as final to prevent inheritance
- Use encryption techniques
To securely serialize and deserialize objects to protect sensitive information, you should use encryption techniques. Encrypting the data before serialization and decrypting it after deserialization ensures that the data remains confidential. While access modifiers and marking classes as final provide some level of security, they don't directly address the need for encryption. Custom logic with encryption and authentication is a comprehensive approach to security.
A ________ is a result-bearing computation that can be canceled and can compute the result asynchronously provided by ExecutorService.
- Callable
- ExecutorService
- Runnable
- Thread
A Callable in Java is a result-bearing computation that can be canceled and can compute the result asynchronously. It is typically used with ExecutorService to perform tasks that return values or throw exceptions.
What is the impact of using a SocketChannel in non-blocking mode over traditional blocking I/O socket communication?
- a. SocketChannel offers better performance with lower CPU usage.
- b. Non-blocking SocketChannel can handle only one connection at a time.
- c. Blocking I/O sockets are more suitable for high-throughput applications.
- d. Non-blocking SocketChannel improves data integrity.
Using SocketChannel in non-blocking mode (option a) can lead to improved performance with lower CPU usage compared to traditional blocking I/O sockets. Non-blocking SocketChannels can handle multiple connections concurrently. Option c is incorrect because non-blocking SocketChannels are often favored for high-throughput scenarios. Option d is not accurate as data integrity is not directly related to blocking or non-blocking mode.
The ________ method of ExecutorService attempts to stop all actively executing tasks and halts the processing of waiting tasks.
- pause()
- shutdown()
- stop()
- terminate()
In Java, the shutdown() method of ExecutorService attempts to stop all actively executing tasks and halts the processing of waiting tasks. It's a graceful way to shut down an executor, allowing it to finish executing tasks before terminating. It is essential to manage thread pools effectively in concurrent applications.
Which of the following statements are true regarding the intern() method of the String class?
- Calling intern() on a String can reduce memory usage by ensuring only one copy exists in the string pool.
- The intern() method adds the String to the string pool.
- The intern() method is only available in Java 9 and later.
- The intern() method returns a new String object.
The intern() method of the String class is used to add the String to the string pool if it's not already there and returns a reference to that String. This can reduce memory usage by ensuring only one copy of a particular string exists in the string pool, which is useful for memory optimization. The intern() method has been available since early versions of Java, not just in Java 9 and later.
Consider a scenario where a very large number of string concatenation operations are being performed in a single-threaded application. Which class would be appropriate to use for string manipulation, and why?
- String
- StringBuffer
- StringBuilder
- StringJoiner
In a single-threaded application with frequent string concatenation, StringBuilder is the most suitable choice. It's efficient because it doesn't create new objects when you modify the string, which can save memory and reduce overhead. StringBuffer is also thread-safe but slightly slower due to synchronization. String creates a new string each time you modify it, and StringJoiner is used for joining strings, not efficient for concatenation.
The operator ______ is invalid in Java.
- $
- %
- +
- -
In Java, the dollar sign ($) is not a valid operator. It's used in variable names and identifiers but not as an operator. The other options (+, -, %) are valid arithmetic operators in Java.
In Java 8 and above, the ________ method can be used to perform a certain action for each element of a collection.
- applyActionToElement() Method
- forEach() Method
- iterate() Method
- processElement() Method
In Java 8 and above, the "forEach()" method is used to perform a specified action for each element of a collection. It provides a concise way to iterate through elements in a collection and apply a given action to each element. The other options do not represent the correct method for this purpose.
How does intrinsic locking in synchronized methods/blocks ensure thread safety?
- It allows all threads to execute synchronized code simultaneously.
- It doesn't affect thread safety.
- It prevents all threads from executing synchronized code simultaneously.
- It relies on hardware-specific instructions.
Intrinsic locking in synchronized methods/blocks ensures thread safety by preventing multiple threads from executing synchronized code simultaneously. When a thread enters a synchronized block, it acquires the lock associated with the synchronized object, preventing other threads from entering the same synchronized block until the lock is released. This ensures that only one thread can execute the synchronized code at a time, preventing data races and ensuring thread safety.