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.
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.
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.
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.
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.