Question

Write a Java statement to accomplish each of the following tasks: a) Declare variables sum and \(x\) to be of type int. b) Assign 1 to variable x. c) Assign 0 to variable sum. d) Add variable \(\times\) to variable sum, and assign the result to variable sum. e) Print "The sum is: ", followed by the value of variable sum.

Short answer

Declare `int sum, x;`, assign `x = 1;`, `sum = 0;`, add with `sum = sum + x;`, and print with `System.out.println("The sum is: " + sum);`.

Step-by-step solution

Declare Variables

First, declare two integer variables named `sum` and `x` using the `int` data type. This sets up the variables for use in subsequent steps. ```java int sum, x; ```

Initialize Variable x

Assign the value 1 to the variable `x`. This initializes the variable so it can be used in arithmetic operations later. ```java x = 1; ```

Initialize Variable sum

Assign the value 0 to the variable `sum`. This sets `sum` to a starting value for future calculations. ```java sum = 0; ```

Perform Addition

Add the value of `x` to `sum` and store the result back in `sum`. This updates `sum` to include the value of `x`. ```java sum = sum + x; ```

Print the Result

Output the string 'The sum is: ' followed by the current value of `sum`, helping to communicate the result. ```java System.out.println("The sum is: " + sum); ```

Key concepts

Variable Declaration

In Java, variable declaration is the first step before using a variable in any calculation or function. To declare a variable, you specify its data type and name. This tells the program what kind of data will be stored and accessed. For example, using the `int` keyword declares variables as integers, which means they can hold whole numbers without decimal points. In our exercise, the statement is `int sum, x;`, which declares two integer variables named `sum` and `x`. This step doesn't assign any values yet but reserves space in the memory to store integer numbers when needed. Remember, a variable's name should be a unique identifier, descriptive, and must start with a letter or underscore.

Initialization

After declaring a variable, the next crucial step is initialization, which means assigning an initial value. Initialization is important because it prepares the variable for use in your program by defining what data it will begin with. Without initialization, a variable could contain random data or "junk" value from memory. In our exercise, after declaring variables, we set `x` to 1 with the code `x = 1;` and `sum` to 0 using `sum = 0;`. This ensures that when you perform operations on these variables, they start with known and controlled values. It's a good practice to always initialize your variables to avoid errors and undesired behavior in your programs.

Arithmetic Operations

Arithmetic operations in Java involve mathematical computations like addition, subtraction, multiplication, and division. For this exercise, we focus on addition. Once your variables are initialized, you can perform operations with them. Adding the value of one variable to another and storing the result is a common arithmetic operation. In the step given, `sum = sum + x;`, effectively adds the value of `x` to `sum` and stores the new total back in `sum`. This simple operation is at the heart of many algorithms and calculations. Keep in mind that arithmetic operations follow operator precedence; operations within parentheses are performed first, followed by multiplication and division, and finally addition and subtraction.

Printing Output

Displaying output in Java is often accomplished with the `System.out.println()` function, which is used to print text and variable data to the console. Printing lets you or the user see the results of the program immediately. In this example, `System.out.println("The sum is: " + sum);` is used to print a message followed by the actual value of `sum`. The `+` operator in this context is used to concatenate strings with variables, thereby combining text with the numeric value stored in `sum`. This technique creates a user-friendly output that dialogues the current state or result of the program. Always ensure your outputs are clear and informative to improve the user experience.