How are Lambda expressions compiled in Java?
- Lambdas are compiled into native machine code for better performance.
- Lambdas are compiled into traditional anonymous inner classes.
- Lambdas are not compiled; they are interpreted at runtime.
- Lambdas are pre-compiled and stored as bytecode in a separate file.
In Java, Lambda expressions are compiled into traditional anonymous inner classes by the Java compiler. These inner classes capture the behavior defined by the Lambda expression. The use of inner classes allows the Java Virtual Machine (JVM) to treat Lambdas as objects with associated methods, which makes them compatible with existing Java features and enables the use of functional interfaces. Understanding this compilation process is crucial for developers who want to understand the inner workings of Lambdas and their impact on the bytecode.
To retrieve the value of the first column in the current row of a ResultSet, you can use the method ________.
- getFirstColumnValue()
- getInt(0)
- getRowValue()
- getString(1)
To retrieve the value of the first column in the current row of a ResultSet, you can use the method getString(1). This method fetches the value of the column at index 1 (the first column) and returns it as a string. The other options are not valid methods for this purpose.
Which of the following code snippets declares a jagged array?
- int jaggedArray[3][];
- int[3][] jaggedArray;
- int[] jaggedArray[3];
- int[][] jaggedArray = new int[3][];
A jagged array is an array of arrays in which the sub-arrays can have different lengths. The correct declaration for a jagged array in Java is option 1, where you specify the number of rows (3) but leave the size of the second dimension unspecified. This allows each sub-array to have a different length.
Consider a scenario where you are working with a list of objects, and you need to sort them based on a specific attribute. How would Lambda expressions be utilized for this?
- By using a loop to iterate through the list and sort the objects manually without Lambda expressions.
- By using the Comparator interface and implementing it with a Lambda expression that specifies the attribute to be used for sorting.
- By using the Sorter class with a Lambda expression as a parameter to specify the attribute for sorting.
- By using traditional sorting algorithms and avoiding Lambda expressions for sorting objects.
In Java, you can use Lambda expressions to simplify sorting tasks, especially when working with lists of objects. By implementing the Comparator interface with a Lambda expression, you can specify the attribute or criteria for sorting. This allows for concise and readable code that promotes reusability and maintainability.
What is the primary difference between Runnable and Callable interfaces?
- Callable can be scheduled for future execution.
- Callable can run without being wrapped in a thread.
- Runnable allows returning a result.
- Runnable can be used for multi-threading.
The primary difference between Runnable and Callable interfaces is that Callable allows you to return a result from the computation, whereas Runnable does not. Callable is typically used when you need a result from a task that can be scheduled for future execution, while Runnable is a simple interface for a task that does not return a result.
The ________ method in the Stream API returns an equivalent stream that is sequential.
- filter
- map
- parallel
- sequential
In the Stream API of Java, the sequential() method is used to return an equivalent stream that is sequential in nature. This method can be useful when you want to ensure that subsequent operations on the stream are executed in a sequential order.
In Java, a variable declared within a method is referred to as a ________ variable.
- Global
- Instance
- Local
- Static
In Java, a variable declared within a method is referred to as a "Local" variable. Local variables are defined within a method and are only accessible within that method's scope. They are used for temporary storage and are typically used to store intermediate results or data specific to a method.
Which arithmetic operator is used to calculate the remainder in JavaScript?
- % (Modulus)
- / (Division)
- * (Multiplication)
- + (Addition)
In JavaScript, the % (Modulus) operator is used to calculate the remainder of a division operation. For example, 7 % 3 equals 1 because when 7 is divided by 3, the remainder is 1.
The main difference between a function expression and a function declaration is the function _________.
- Hoisting
- Scope
- Expression
- Name
The main difference between a function expression and a function declaration is the function name. Function declarations have a name, which is used to call the function, while function expressions may or may not have a name, depending on whether they are named or anonymous functions.
Which method is preferred to loop through an array in ES6 and onwards?
- for loop
- for...in loop
- forEach method
- while loop
In ES6 and onwards, the preferred method to loop through an array is the forEach method. It provides a concise way to iterate over array elements and execute a function for each element. The for loop and for...in loop are less commonly used for iterating arrays, and the while loop is a general-purpose loop that can be used but is not specifically designed for array iteration.