Question

Write statements to accomplish each of the following tasks: a) Declare variables \(c,\) this IsAVariable, \(q 76354\) and number to be of type int. b) Prompt the user to enter an integer. c) Input an integer and assign the result to int variable value. Assume Scanner variable input can be used to read a value from the keyboard. d) If the variable number is not equal to \(7,\) display "The variable number is not equal to \(7 "\) e) Print "This is a Java program" on one line in the command window. f) Print "This is a Java program" on two lines in the command window. The first line should end with Java. Use method System.out.print1n. g) Print "This is a Java program" on two lines in the command window. The first line should end with Java. Use method System. out.printf and two \(\%\) s format specifiers.

Short answer

Declare variables, prompt user input, assign input, use if statement for conditional check, and print messages using println and printf.

Step-by-step solution

Declare Integer Variables

In Java, to declare variables of a specific type, you use the type followed by the variable names, separated by commas. For the variables \( c \), `thisIsAVariable`, \( q76354 \), and `number`:```javaint c, thisIsAVariable, q76354, number;```

Prompt for User Input

To prompt the user to enter an integer, you can use `System.out.println` or `System.out.print`: ```java System.out.println("Please enter an integer:"); ```

Read Input and Assign to Variable

To read an integer from user input and assign it to a variable, use the Scanner class. Assuming `input` is a Scanner object already initialized, read the integer as follows: ```java int value = input.nextInt(); ```

Conditional Statement

To display a message if `number` is not equal to 7, use an if statement: ```java if (number != 7) { System.out.println("The variable number is not equal to 7"); } ```

Print Single Line Message

To print a message on one line, use `System.out.println`: ```java System.out.println("This is a Java program"); ```

Print Multi-Line Message with println

To print a message on two lines using \( System.out.println \), with the first line ending in 'Java':```javaSystem.out.println("This is a Javaprogram");```

Print Multi-Line Message with printf

To print a message on two lines using \( System.out.printf \) and format specifiers, with the first line ending in 'Java':```javaSystem.out.printf("This is a Java%sprogram%n", "");```

Key concepts

Java Variables

Variables in Java are fundamental in storing and manipulating data values throughout a program. When you declare a variable in Java, you define a storage location with a specific type, such as an integer (int), floating-point number (float), or others.
For instance, declaring integers can be done succinctly by listing variable names separated by commas after the keyword `int` as shown in the original solution:

• `int c, thisIsAVariable, q76354, number;`

This statement tells the Java compiler to allocate memory for four integer values and ties them to the names provided. Proper naming conventions should be followed, such as starting variable names with a letter, not a number, and using camelCase for readability.

Input Handling in Java

Handling user input in Java typically involves the use of the Scanner class, which allows reading different types of data from various sources. This is especially valuable for interactive programs where user feedback influences behavior.
To begin collecting data through the command line, a Scanner object needs to be initialized:

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

With the Scanner object (here named `input`), you can capture user input. To read an integer, use the method `nextInt()`:

• `int value = input.nextInt();`

Always remember to prompt the user before input collection to ensure the user knows when and what to input, using `System.out.println` or similar methods.
After reading a value, it's a good practice to close the Scanner object using `input.close()` to free resources.

Conditional Statements in Java

Conditional statements allow decision-making in Java programs, executing different paths based on conditions. A common conditional statement is the `if` statement, which checks boolean expressions.
Consider the scenario where you want to check whether a variable does not match a specific value. For instance, if you want to display a message if an integer variable named `number` is not 7:

• `if (number != 7) { System.out.println("The variable number is not equal to 7"); }`

In this example, the condition `number != 7` checks for inequality. If `number` isn't 7, the message within the curly braces is executed. Conditional statements are versatile, supporting multiple conditions and outcomes, enhancing program functionality significantly.

Output in Java

Outputting information in Java is crucial for user interaction and debugging. The `System.out` is a standard output stream, frequently employed via `println`, `print`, and `printf` methods.

• `System.out.println("This is a Java program");`

The method `println` automatically appends a newline character after printing the text.
To introduce more control over text output, `printf` can be used. It allows formatted strings with `%s` format specifiers, among others. For example splitting "This is a Java program" into two lines:

• `System.out.printf("This is a Java%sprogram%n", "");`

Here, `%s` acts as a placeholder for a string, and `%n` introduces a platform-independent newline. Understanding these methods improves both presentation and readability of the output in a Java application.