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.
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.
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.
The class ________ is used to create a text field in JavaFX.
- JText
- Text
- TextField
- TextInputField
In JavaFX, the TextField class is used to create a single-line text input field. It allows users to enter text or data. The other options, Text, TextInputField, and JText, are not the correct classes for creating text fields in JavaFX.
Which method of the String class is used to compare two strings for equality, ignoring case differences?
- compareTo()
- compareToIgnoreCase()
- equals()
- equalsIgnoreCase()
In Java, the equalsIgnoreCase() method of the String class is used to compare two strings for equality while ignoring differences in case. It returns true if the two strings are equal, regardless of whether the characters are in uppercase or lowercase. The other options, equals(), compareToIgnoreCase(), and compareTo(), do not perform case-insensitive comparisons.
What does the getConnection method of DriverManager class do?
- Closes an existing connection.
- Establishes a connection to a database.
- Executes a SQL query.
- Retrieves the JDBC driver's info.
The getConnection method of the java.sql.DriverManager class is used to establish a connection to a database. It takes parameters like the database URL, username, and password to create a connection to the specified database server. It does not close connections, retrieve driver info, or execute SQL queries.
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.
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.
The ________ keyword is used to declare objects that cannot change.
- final
- static
- transient
- volatile
The final keyword in Java is used to declare objects that cannot change after they are initialized. It can be applied to variables, methods, and classes to make them unmodifiable, constant, or not extendable, respectively.
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.