Question

Write declarations, statements or comments that accomplish each of the following tasks: a) State that a program will calculate the product of three integers. b) Create a Scanner that reads values from the standard input. c) Declare the variables \(x, y, z\) and result to be of type int. d) Prompt the user to enter the first integer. e) Read the first integer from the user and store it in the variable \(x\). f) Prompt the user to enter the second integer. g) Read the second integer from the user and store it in the variable \(y\). h) Prompt the user to enter the third integer. i) Read the third integer from the user and store it in the variable \(z\). jompute the product of the three integers contained in variables \(x, y\) and \(z,\) and assign the result to the variable result. k) Display the message "Product is" followed by the value of the variable result.

Short answer

Declare variables, create Scanner, prompt and read inputs, compute product, display result.

Step-by-step solution

Program Purpose Declaration

Write a comment at the top of the program to state its purpose: ``` // This program calculates the product of three integers. ```

Create a Scanner Object

Instantiate a Scanner object to read input from the standard input: ```java Scanner scanner = new Scanner(System.in); ```

Declare Variables

Declare the variables for storing the integers and their product: ```java int x, y, z, result; ```

Prompt for First Integer

Instruct the user to input the first integer: ```java System.out.print("Enter first integer: "); ```

Read First Integer

Capture the first integer input by the user and store it in variable x: ```java x = scanner.nextInt(); ```

Prompt for Second Integer

Ask the user to input the second integer: ```java System.out.print("Enter second integer: "); ```

Read Second Integer

Read the next integer input by the user and store it in variable y: ```java y = scanner.nextInt(); ```

Prompt for Third Integer

Request the user to input the third integer: ```java System.out.print("Enter third integer: "); ```

Read Third Integer

Collect the third integer input from the user and store it in variable z: ```java z = scanner.nextInt(); ```

Compute Product

Calculate the product of the three integers and assign the result to the variable 'result': ```java result = x * y * z; ```

Display Product

Output the message indicating the product, followed by the value of 'result': ```java System.out.println("Product is " + result); ```

Key concepts

Integer Variables

In Java programming, integer variables are a foundational element used to store whole numbers. These variables are defined using the keyword `int`. When you declare a variable as an integer, you specify that it can store values without decimal points.

For instance, if you want to handle values such as 5, 100, or -42 in your program, you would use integer variables. In the provided exercise, the variables `x`, `y`, `z`, and `result` are all declared as integer variables. This ensures they can only store whole numbers, which is appropriate for simple arithmetic tasks such as calculating a product.

Using integer variables is efficient as they consume less memory compared to other numeric types, like floating-point variables. However, remember that they cannot store fractional numbers, and attempting to do so will result in data loss. Therefore, they are perfect for computations involving counts or exact whole numbers.

User Input Handling

User input handling in Java is executed using classes and methods that can read user data from different input sources, such as the keyboard. One of the most commonly used classes for this purpose is the `Scanner` class in the `java.util` package.

To get started with user input handling, you first need to import the `Scanner` class. Next, create an instance of the `Scanner` class and link it to the standard input stream, typically `System.in`, which represents keyboard input. This can be done as shown:

• `Scanner scanner = new Scanner(System.in);`

This line of code creates a `Scanner` object that reads from the keyboard, allowing you to capture input entered by the user.

In the exercise, you read multiple integers from the user using the `nextInt()` method of the `Scanner` object. This method waits for the user to enter an integer and then stores it in the specified variable. Always ensure user input is validated to handle incorrect formats and prevent runtime errors.

Control Structures

Control structures in Java dictate the flow of execution throughout the program. When building interactive programs that respond to user input, control structures guide how different parts of the code interact.

In the provided exercise, the program primarily uses sequential control flow. This means each statement is executed one after the other without deviation, unless specified otherwise by more complex structures like loops or conditionals (which you might not see directly in this exercise).

Prompting the user, reading input, computing the product, and displaying the result are all handled in a linear manner. Each operation depends on the successful completion of the previous one, ensuring a clear flow from start to finish. For more complex tasks, incorporating loops or conditional statements may be necessary, but for straightforward input and output operations like in this program, sequential control is sufficient.

Arithmetic Operations

Arithmetic operations in Java are fundamental to performing calculations. These operations consist of addition, subtraction, multiplication, division, and modulus.

In this exercise, we focus on multiplication to calculate the product of three integers. The multiplication operation is denoted by the `*` operator in Java. When you perform arithmetic operations, such as:

• `result = x * y * z;`

the program computes the product of the values stored in variables `x`, `y`, and `z`, and then assigns the result to the `result` variable.

Arithmetic operations are executed following the precedence of operators. Multiplication and division are performed before addition and subtraction unless parentheses dictate differently. For the exercise's straightforward arithmetic task, understanding the basic operators ensures the correct computation of desired outcomes. Handling arithmetic tasks efficiently in programming requires knowing these operators and their precedence.