Which sorting algorithm repeatedly steps through the list, compares adjacent elements, and swaps them if they are in the wrong order?
- Bubble Sort
- Insertion Sort
- Merge Sort
- Quick Sort
Bubble Sort is a simple sorting algorithm that repeatedly steps through the list to be sorted, compares adjacent elements, and swaps them if they are in the wrong order. It is known for its simplicity but is less efficient than other sorting algorithms like Quick Sort and Merge Sort in terms of time complexity.
The method ________ of the RandomAccessFile class sets the file-pointer offset.
- moveFilePointer()
- seek()
- setFilePointer()
- setPointerOffset()
The method seek() of the RandomAccessFile class in Java is used to set the file-pointer offset to a specified location within the file. It allows you to navigate within the file and start reading or writing data from that position.
What happens if a superclass is not serializable but its subclass is, and we serialize an object of the subclass?
- Only the subclass fields will be serialized.
- Serialization will fail.
- Serialization will proceed without errors.
- The superclass fields will be serialized, but not the subclass fields.
If a superclass is not serializable but its subclass is, attempting to serialize an object of the subclass will result in a java.io.NotSerializableException. This happens because the superclass needs to be serializable for the serialization process to work correctly. The other options are incorrect, as they imply successful serialization without issues.
What is the purpose of using URL Encoding in Java?
- To encrypt URLs for secure communication
- To ensure special characters are transmitted properly
- To optimize URL routing for faster navigation
- To shorten URLs for better performance
URL Encoding in Java is used to ensure that special characters, such as spaces or symbols, are properly transmitted in URLs. It replaces reserved characters with escape sequences to prevent issues in URL handling and parsing. The other options do not accurately describe the purpose of URL Encoding.
When a thread tries to access a synchronized block of code in an object, it must first obtain the ________ on the object.
- Lock
- Monitor
- Semaphore
- Semaphore
When a thread tries to access a synchronized block in Java, it must first obtain the "Lock" on the object. This ensures that only one thread can execute the synchronized code block at a time, preventing race conditions.
The ________ method of URL class provides the port number of the URL.
- fetchPortNumber()
- getPort()
- obtainPort()
- retrievePort()
The correct answer is getPort(). In Java, the URL class provides the getPort() method, which allows you to obtain the port number of a URL. This is useful when working with network-related tasks where you need to know the port associated with a particular URL.
Which class is commonly used for reading characters from a file in Java?
- FileInputReader
- FileOutputReader
- FileReader
- FileWriter
In Java, the commonly used class for reading characters from a file is FileReader. It is part of the java.io package and is specifically designed for character input. Other options like FileWriter, FileInputReader, and FileOutputReader are not standard classes in Java for file reading.
To obtain a string representation of a primitive data type, you can use the static valueOf method of the ________ class.
- Double
- Float
- Integer
- String
In Java, you can use the static valueOf method of the Integer class to obtain a string representation of a primitive data type. For example, Integer.valueOf(42) will return the string "42". The other options do not provide this specific functionality.
How does the Merge Sort algorithm behave in terms of space complexity?
- It has a space complexity of O(1) as it sorts the array in place without using additional memory.
- It has a space complexity of O(log n) because it divides the array into smaller subarrays, reducing memory usage.
- It has a space complexity of O(n) because it creates a temporary array to hold the merged subarrays.
- It has a space complexity of O(n^2) due to the need for additional memory for merging subarrays.
Merge Sort has a space complexity of O(n) because it creates a temporary array to hold the merged subarrays during the sorting process. Unlike some other sorting algorithms like Quick Sort, Merge Sort does not use a constant amount of extra memory (O(1)) or divide the memory usage logarithmically (O(log n)).
What does the Serializable interface contain?
- A set of methods for creating new objects
- A set of methods for mathematical calculations
- A set of methods for serializing objects
- A set of methods for sorting objects
The Serializable interface in Java does not contain any methods. Instead, it serves as a marker interface, indicating that the class implementing it can be serialized. Serialization allows objects to be converted into a byte stream for storage or transmission. It's used for objects that need to be saved to a file or sent over a network.