A class in Java can contain _______, which are used to describe the properties of objects.
- Constructors
- Interfaces
- Methods
- Variables
In Java, a class can contain variables, which are used to describe the properties or attributes of objects. Methods are used to define the behaviors of objects. Constructors initialize objects, and interfaces declare methods that must be implemented.
Which method is used to submit a task for execution to the ExecutorService and returns a Future object?
- addTaskToExecutor(Runnable task)
- execute(Runnable task)
- startTask(Callable
task) - submit(Runnable task)
The submit(Runnable task) method of the ExecutorService interface is used to submit a task for execution and returns a Future object. This Future can be used to monitor the progress and retrieve the result of the task asynchronously. The other options are not correct methods for submitting tasks to an ExecutorService.
Consider a multi-threaded environment, how can a loop potentially cause a race condition?
- The loop uses a single shared variable among multiple threads without proper synchronization, causing unpredictable results.
- The loop has a long execution time, increasing the likelihood of context switches and thread interference.
- The loop uses thread-local variables, eliminating the possibility of race conditions.
- The loop uses a synchronized keyword, ensuring thread safety.
In a multi-threaded environment, a race condition can occur when multiple threads access and modify a shared variable concurrently without proper synchronization. Option 1 correctly identifies this scenario. Option 2 refers to context switching but not directly to race conditions. Option 3 is a preventative measure, and Option 4 is a solution to race conditions, not a cause.
What issues might arise if methods modifying static variables are not synchronized?
- Deadlocks may occur.
- Inconsistent or incorrect values can be assigned to static variables.
- No issues will arise.
- Only one thread can access static variables.
If methods modifying static variables are not synchronized, it can result in inconsistent or incorrect values being assigned to those variables. Since multiple threads can access and modify static variables concurrently, without synchronization, they may read and write to the variable at the same time, leading to data corruption or inconsistent state. Proper synchronization is essential to ensure thread safety when working with shared static variables.
Synchronized methods prevent thread interference and memory consistency errors by allowing ________ thread(s) to execute the method's entire body.
- all but one
- multiple
- no additional thread(s)
- only one
Synchronized methods in Java allow only one thread to execute the method's entire body at a time. This ensures that there is no concurrent execution, preventing thread interference and memory consistency errors. Other threads are blocked until the executing thread completes the synchronized method. This is a fundamental concept in Java for ensuring thread safety.
Which data structure is preferred for implementing Binary Search effectively?
- Array
- Binary Tree
- Hash Table
- Linked List
Binary Search is most effectively implemented with a sorted array. This is because arrays provide direct access to elements by index, which is crucial for the binary search algorithm's efficiency. Binary trees and hash tables do not provide direct index-based access, making them less suitable for binary search. Linked lists can be used, but they may not offer the same performance advantages as arrays.
In a multi-threaded environment, which class (StringBuffer or StringBuilder) would you primarily use and why?
- Both StringBuffer and StringBuilder can be used interchangeably
- Neither StringBuffer nor StringBuilder should be used in a multi-threaded environment
- StringBuffer
- StringBuilder
In a multi-threaded environment, StringBuilder is primarily used due to its better performance. Unlike StringBuffer, StringBuilder is not synchronized, which makes it more efficient when thread safety is not a concern. StringBuffer is synchronized and is used when thread safety is required. Using both interchangeably may lead to synchronization overhead.
What is the major drawback of Linear Search compared to other searching algorithms?
- Linear Search has a high time complexity.
- Linear Search is not easily implemented.
- Linear Search is not suitable for sorted data.
- Linear Search requires extra memory.
The major drawback of Linear Search is that it is not efficient for searching in large sets of sorted data. Unlike Binary Search or Hashing, which have logarithmic time complexity, Linear Search has a linear time complexity, making it slower for large datasets. It doesn't take advantage of data being sorted. The other options do not accurately represent the primary drawback of Linear Search.
How can you configure the thread names of an ExecutorService for debugging and identification purposes?
- Thread names are automatically derived from the name of the task submitted to the ExecutorService.
- You can change thread names by calling the setName method on the ExecutorService instance after it's created.
- You can set the thread names when creating a new thread pool using the ThreadFactory interface and providing a custom ThreadFactory implementation.
- You cannot configure thread names for threads in an ExecutorService; they are automatically generated by Java.
To configure thread names of an ExecutorService for debugging and identification purposes, you can provide a custom ThreadFactory implementation when creating the thread pool. This allows you to set meaningful names for the threads, making it easier to identify their purpose in logs and debugging. Thread names are not automatically configurable and are typically based on the default naming conventions unless you specify otherwise.
When a class implements Serializable, it should have a static final field named ______.
- classVersion
- serialVersion
- serialVersionUID
- versionID
When a class implements the Serializable interface, it's recommended to have a static final long serialVersionUID field. This field helps ensure that the serialized and deserialized versions of the class are compatible. It's used to verify that the class being deserialized is compatible with the one that was originally serialized. The other options are not standard.
The process of converting a primitive data type to a wrapper class object in Java is known as ________.
- Autoboxing
- Casting
- Parsing
- Unboxing
The process of converting a primitive data type to a wrapper class object in Java is known as "Autoboxing." Autoboxing is the automatic conversion of primitive data types to their corresponding wrapper classes. For example, converting an int to an Integer.
The method replace(oldChar, newChar) belongs to the ________ class in Java.
- Character
- String
- StringBuilder
- StringManipulator
The replace(oldChar, newChar) method in Java belongs to the String class. This method is used to replace all occurrences of oldChar with newChar in a given string. The other classes listed do not have this specific method.