The ________ method is used to move the thread into the Ready/Runnable state.
- join()
- sleep()
- start()
- wait()
The "start()" method is used to move a thread into the Ready/Runnable state in Java. When a thread is started using "start()", it becomes eligible for execution, and the JVM schedules it for execution at the appropriate time.
How can you access variables in the surrounding scope from a lambda expression?
- They are automatically accessible within the lambda.
- You can access them using the super keyword.
- You cannot access them.
- You need to pass them as parameters to the lambda expression.
To access variables from the surrounding scope within a lambda expression, you typically need to pass them as parameters to the lambda expression. This is known as "capturing" variables. Lambda expressions in Java can access effectively final local variables and instance variables. Attempting to access non-final variables can result in compilation errors.
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.
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.
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.
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.
A variable declared as double d = 10.3; occupies ________ bytes of memory.
- 16
- 2
- 4
- 8
In Java, a variable of type "double" occupies 8 bytes of memory. The "double" data type is a 64-bit floating-point type that can hold both integer and fractional values. It requires 8 bytes to store its precision and range, making it suitable for storing large and decimal numbers with high precision.
In Java, constructors have the same name as the _______.
- Class
- Method
- Package
- Variable
In Java, constructors have the same name as the class in which they are defined. This naming convention allows you to identify and use the constructor associated with a particular class.
Which method is used to check if there are more lines of text to read from a BufferedReader object?
- canReadMore()
- hasMoreLines()
- hasNext()
- hasNextLine()
The BufferedReader class has a method called hasNextLine() that is used to check if there are more lines of text to read from the BufferedReader object. It returns true if there are more lines and false if the end of the file has been reached. The other options do not represent the correct method for this purpose.
Consider a scenario where an application retrieves a large amount of data from a database and displays it in a UI paginated form. How would you efficiently manage and optimize data retrieval and display using JDBC?
- Implementing client-side caching of database results to improve data retrieval speed for pagination.
- Loading all data into memory and applying pagination through custom code to limit the data displayed in the UI.
- Retrieving all data at once and performing pagination on the client side using Java collections.
- Using JDBC ResultSet's pagination features, like setFetchSize, to fetch data in smaller chunks from the database.
When dealing with large data sets, it's essential to retrieve and display data efficiently. JDBC provides features like setFetchSize to fetch data in smaller portions, reducing memory usage and improving performance. Retrieving all data at once can lead to memory issues. Client-side caching can help, but it may not be suitable for very large datasets. Understanding these JDBC features is crucial for optimization.
Which data type would be suitable to store a character value in Java?
- byte
- char
- double
- float
In Java, the char data type is used to store a single character. It can hold any character, including letters, numbers, and special symbols.
How can you read an 8-bit byte from a file using byte streams in Java?
- BufferedReader
- FileReader
- FileReader
- InputStream
To read an 8-bit byte from a file using byte streams in Java, you should use the InputStream class. Byte streams are designed to work with binary data, and InputStream is the parent class for all byte input streams. FileReader and BufferedReader are used for character-based reading, not for reading raw bytes.