Imagine you are developing a multi-threaded application for a bank. How would you ensure that when multiple threads are trying to update the same account, the account data remains consistent?
- Employing optimistic locking techniques such as versioning, where each thread checks a version number before updating the account.
- Implementing thread-safe data structures like ConcurrentHashMap to store account information.
- Using synchronized methods or blocks to lock access to the account data when it's being updated.
- Utilizing atomic operations provided by classes like AtomicInteger to ensure atomic updates of account data.
In a multi-threaded bank application, consistency can be achieved by using synchronized methods or blocks to ensure that only one thread can access and update the account data at a time. This prevents race conditions and data corruption. Other options, like using thread-safe data structures or atomic operations, can help with performance but may not guarantee consistency in complex scenarios. Optimistic locking with versioning can also be used to handle concurrent updates.
Which of the following classes is used to create a button in JavaFX?
- Button
- CheckBox
- Label
- TextField
In JavaFX, the Button class is used to create a button. Buttons are interactive elements in a graphical user interface, and you can use the Button class to create them and add event handlers. The other classes mentioned are used for different purposes.
Which of the following primitive data types has the largest size in memory?
- byte
- double
- long
- short
Among the primitive data types listed, double has the largest size in memory. It is a 64-bit data type and can store large floating-point numbers with precision. The other options (byte, short, long) have smaller memory footprints.
How can you read data from a URL using Java?
- Use the InputStream class
- Use the Scanner class
- Use the URLConnection class
- Use the readData() method
To read data from a URL in Java, you typically use the URLConnection class to open a connection to the URL and then use the InputStream class to read the data. The other options are not standard methods for reading data from a URL.
Which operator can be used to invert the sign of a numeric expression?
- !
- +
- -
- ~
The - (minus) operator can be used to invert the sign of a numeric expression. For example, if you have a variable int x = 5;, then -x would give you -5. The other options are not used for inverting the sign of numeric values.
Which of the following is a valid method to execute a stored procedure using JDBC?
- CallableStatement.execute() with a procedure
- executeQuery() with a stored procedure call
- executeStoredProc()
- executeUpdate() with a stored procedure call
To execute a stored procedure using JDBC, you typically use the CallableStatement interface and its execute() method with a procedure call. The other options (executeStoredProc(), executeQuery() with a stored procedure call, and executeUpdate() with a stored procedure call) are not standard methods for executing stored procedures in JDBC.
How can transactions be managed in JDBC to ensure data integrity?
- By using Connection.setAutoCommit(false) and manually committing transactions using Connection.commit()
- By using Connection.setAutoCommit(true) and allowing transactions to automatically commit on every SQL statement execution
- By using Connection.setReadOnly(true) to prevent any data modification, thus ensuring data integrity
- By using Connection.setTransactionIsolation() to set the desired isolation level, ensuring data consistency
In JDBC, transactions can be managed by setting auto-commit to false using Connection.setAutoCommit(false). This allows you to manually commit transactions using Connection.commit(). This approach ensures data integrity by allowing you to group multiple SQL statements into a single transaction and ensuring that they are either all executed or none at all. Setting auto-commit to true (option 2) will not provide the same level of control over transactions. Options 3 and 4 are unrelated to managing transactions in this context.
To specify a repeating behavior in an animation, ______ method is used in JavaFX.
- cycleAnimation()
- repeatAnimation()
- setCycleCount()
- setRepeatCount()
In JavaFX, the setCycleCount() method is used to specify the number of times an animation should repeat. By setting the cycle count to a specific value, you can control how many times the animation should loop or repeat, creating repeating behaviors in your animations.
Which of the following classes is mainly used to establish a connection to the database in JDBC?
- java.sql.Connection
- java.sql.DriverManager
- java.sql.ResultSet
- java.sql.Statement
The java.sql.DriverManager class in JDBC is primarily used for establishing database connections. It provides methods like getConnection to create connections to a database server. The other classes mentioned (Connection, Statement, and ResultSet) are used after the connection is established for various database operations.
Imagine you are working on a system that heavily utilizes serialization. How would you manage a scenario where sensitive data, such as passwords, should not be serialized?
- Encrypt the sensitive data before serialization and decrypt it after deserialization
- Implement a custom writeObject method to exclude the sensitive data during serialization
- Use a separate, non-serializable class to store sensitive data
- Use the transient keyword to mark the sensitive data
The transient keyword is used to indicate that a field should not be serialized. In this scenario, marking sensitive data fields as transient ensures that they are excluded from serialization. Implementing a custom writeObject method allows fine-grained control over the serialization process. Encrypting the data is a valid approach but doesn't directly address the issue of excluding it from serialization. Using a separate class for sensitive data avoids serialization issues but is not directly related to the question.