In Java 8, the Stream API introduces the concept of stream processing, which is influenced by the ________ paradigm.
- functional
- imperative
- object-oriented
- procedural
The Stream API in Java 8 is influenced by the functional programming paradigm. Functional programming focuses on treating computation as the evaluation of mathematical functions, which aligns well with the stream processing concept in Java's Stream API.
What will be the result of attempting to compile and run a Java class that contains a variable declared as int public;?
- A compilation error will occur due to using a reserved keyword as a variable name.
- The code will compile and run without errors.
- The code will compile but result in a runtime error.
- The code will compile but will produce a warning message.
In Java, "public" is a reserved keyword used to declare access modifiers. Using it as a variable name will result in a compilation error since you cannot use reserved keywords as variable names. This is a fundamental rule in Java's syntax. Attempting to compile and run such code will indeed lead to a compilation error.
Imagine you are developing a multi-threaded application where threads are performing both read and write operations on shared resources. How would you ensure that the data is not corrupted without degrading performance significantly?
- Avoid synchronization altogether and use atomic operations.
- Implement read-write locks to allow multiple readers or a single writer.
- Use a single global lock for all shared resources.
- Use fine-grained locks for individual data elements.
In a multi-threaded application with both read and write operations on shared resources, using read-write locks is an effective approach. Read operations can occur concurrently, while write operations are exclusive. Fine-grained locks might lead to excessive contention and performance degradation. Using a single global lock can lead to contention, while avoiding synchronization altogether can risk data corruption.
The method ________ is used to send HTTP GET request without parameters.
- doGet()
- executeGET()
- get()
- sendGET()
In Java, to send an HTTP GET request without parameters, you typically use the sendGET() method. This method is commonly used in HTTP client libraries to initiate a GET request to a specified URL. The other options are not standard methods for this purpose.
What symbol is used in the syntax of a Lambda expression in Java?
- ->
- ::
- =>
- {}
In Java, the syntax of a lambda expression uses the -> symbol. It separates the lambda parameters from the lambda body and is a distinctive feature of lambda expressions, making them easy to identify in code.
If a and b are boolean expressions, then a & b is true only if ______.
- a or b
- both a and b
- either a or b
- neither a nor b
In Java, the '&' operator is a bitwise AND operator. To perform a logical AND operation on boolean expressions, you should use '&&' instead. It returns true if both 'a' and 'b' are true.
In memory, the rows of a two-dimensional array in Java can be __________.
- none of the above
- stored as linked lists
- stored in random order
- stored sequentially
In Java, the rows of a two-dimensional array are stored sequentially in memory. This means that the elements of each row are stored one after the other in memory, making it more efficient for accessing elements in a row. This sequential storage pattern is different from languages like C, where a 2D array is essentially an array of pointers to individual rows.
To execute a batch of commands, we use the ________ method.
- execute()
- executeBatch()
- executeQuery()
- executeUpdate()
In JDBC, the executeBatch() method is used to execute a batch of SQL commands in a single call to the database. This can be more efficient than executing each command individually, especially when you need to perform multiple operations in a single batch, such as inserts, updates, or deletes.
Can a constructor return a value in Java?
- Yes, a constructor can return a value, which is the default value of the class's primary data type.
- No, constructors cannot return values in Java.
- A constructor can return values, but only if it has the same name as the class.
- A constructor can return values, but they must be of type 'void.'
b) is correct. Constructors in Java cannot return values, and their return type is always 'void.' a), c), and d) are incorrect statements.
The keyword ________ is used within a constructor to call another constructor in the same class.
- constructor()
- extend()
- super()
- this()
In Java, the this() keyword is used within a constructor to call another constructor in the same class. This is called constructor chaining and allows you to reuse code logic among constructors in a class. The super() keyword is used to call a constructor of the superclass. The other options are not valid for constructor invocation.