Envisage a situation where you are developing a high-throughput application where multiple threads are reading and writing to a data structure. Which collection would you select to store data and why?
- ArrayList
- ConcurrentHashMap
- HashSet
- LinkedList
In this scenario, a ConcurrentHashMap is the preferred choice. It's designed for concurrent access by multiple threads, making it suitable for high-throughput applications. Unlike ArrayList, LinkedList, and HashSet, it provides thread-safety without sacrificing performance. It achieves this through a mechanism that allows multiple threads to read concurrently while providing efficient locking for write operations.
The ________ method of HttpURLConnection class is used to make the connection to the remote object referred by the URL.
- connect()
- createConnection()
- makeConnection()
- openConnection()
To make a connection to the remote object referred to by a URL using HttpURLConnection, you use the openConnection() method. This method initializes and opens a connection to the specified URL. The other options are not standard methods for this purpose.
When using PrintWriter, the method ________ can be used to flush the stream and check its error state.
- checkError()
- close()
- flush()
- write()
In PrintWriter, the method checkError() can be used to flush the stream and check its error state. This method is handy when you want to make sure that all data is written and no errors occurred.
Imagine you are developing a gaming application where the player's state needs to be saved and restored effectively. How would you manage the serialization of objects in a way that the player's progress, including scores and levels, is efficiently stored and retrieved?
- Serialize the entire game state, including scores and levels, into a single object for easy storage and retrieval.
- Implement a custom serialization process that selectively serializes only the necessary player progress data, reducing storage and transmission overhead.
- Use a database management system to store and retrieve player progress data, eliminating the need for custom serialization.
- Compress the serialized data before storage and transmission to reduce the data size and optimize efficiency.
In a gaming application, efficient serialization of player progress is essential. Option 2 is the correct choice because it allows for selective serialization, reducing overhead by serializing only the necessary data. Option 1 may result in unnecessary data serialization. Option 3 is a valid approach but involves a different technology (DBMS). Option 4 focuses on data size optimization but doesn't address the serialization process itself.
Why might a programmer choose to use package-private (default) access level over private for a method within a class?
- Package-private methods allow access to subclasses, promoting code reusability within the same package.
- Package-private methods are accessible from outside the class, making them more versatile.
- Package-private methods are more restrictive than private methods and provide better encapsulation.
- Private methods cannot be used within a class.
Programmers might choose package-private access level for a method when they want to allow subclasses to access the method for code reuse but restrict access from outside the package. It strikes a balance between encapsulation and reusability, making it a useful choice in certain situations.
In Java, the ______ operator is used to increment a variable's value by 1.
- *
- ++
- --
- /
In Java, the "++" operator is used to increment a variable's value by 1. For example, "int x = 5; x++; // x is now 6". The other options do not perform this specific operation.
Which class would you use for reading binary data from a file?
- BinaryReader
- BufferedReader
- FileInputStream
- FileReader
To read binary data from a file in Java, you should use the FileInputStream class. It's designed for reading raw binary data and doesn't interpret the data as characters. Other options, like FileReader and BufferedReader, are meant for reading text data and may not handle binary data correctly.
What is the purpose of using getters and setters in Java?
- To access and modify the private attributes
- To create objects
- To declare variables
- To perform mathematical operations
Getters and setters are used to access and modify the private attributes (variables) of a class. They help in achieving encapsulation by providing controlled access to the class's internal state. Getters allow reading the value, and setters allow modifying it while enforcing rules and validation.
Which method is used to properly stop a JavaFX application?
- Application.stop();
- Platform.exit();
- System.exit(0);
- stage.close();
To properly stop a JavaFX application, the Application.stop() method should be used. This method is automatically called when the JavaFX application is exiting. It provides a clean way to release resources, close windows, and perform any necessary cleanup operations before the application terminates. Using System.exit(0) or closing the stage directly may not handle cleanup tasks properly.
The InetAddress class provides methods to get the IP address of a local computer by using method ________.
- getHostAddress()
- getIPAddress()
- getLocalAddress()
- getLocalHost()
In Java, you can obtain the IP address of the local computer using the getLocalHost() method of the InetAddress class. It returns an InetAddress object representing the local host's IP address. The other options are not used for this purpose.