Workbook 4.5

From Java Bootcamp Resources -> Module 1 -> 4. Functions, open Workbook 4.5.

Area Calculator

In this workbook, you will calculate the area of a square, rectangle, triangle, and circle.

Task 1: area of a square

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• Function name:

/**
 * Name: areaSquare  <------
 * @param side (double)
 * @return the area (double)
 *
 * Inside the function:
 *  1. If side is negative
 *        - prints "Impossible"
 *        - shuts the app down
 *  2. Calculates the area of the square. A = side²
 */

• Parameters:

/**
 * Name: areaSquare
 * @param side (double)  <--------
 * @return the area (double)
 *
 * Inside the function:
 *  1. If side is negative
 *        - prints "Impossible"
 *        - shuts the app down
 *  2. Calculates the area of the square. A = side²
 */

• Return value:

/**
 * Name: areaSquare
 * @param side (double)
 * @return the area (double) <--------
 *
 * Inside the function:
 *  1. If side is negative
 *        - prints "Impossible"
 *        - shuts the app down
 *  2. Calculates the area of the square. A = side²
 */

• Inside the function:

/**
 * Name: areaSquare - returns the area of a square.
 * @param side (double)
 * @return the area (double)
 *
 * Inside the function: <---------
 *  1. If side is negative
 *        - prints "Impossible"
 *        - shuts the app down
 *  2. Calculates the area of the square. A = side²
 */

$Area = side²$

Use a Math function to calculate side to the power of 2.

Task 2: area of a rectangle

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Write a function that calculates the area of a rectangle.

$Area = length * width$

1. Function name.

/**
 * Name: areaRectangle    <------
 * @param length (double).
 * @param width  (double).
 * @return the area (double)
 *
 * Inside the function:
 *  1. If the length OR width is negative
 *       - print "Error: impossible" and
 *       - terminate the program.
 *  2. return the area: length * width
 */

2. Parameters.

/**
 * Name: areaRectangle
 * @param length (double).  <-----
 * @param width  (double).  <-----
 * @return the area (double)
 *
 * Inside the function:
 *  1. If the length OR width is negative
 *       - print "Error: impossible" and
 *       - terminate the program.
 *  2. return the area: length * width
 */

3. Return value.

/**
 * Name: areaRectangle
 * @param length (double).
 * @param width  (double).
 * @return the area (double)   <------
 *
 * Inside the function:
 *  1. If the length OR width is negative
 *       - print "Error: impossible" and
 *       - terminate the program.
 *  2. return the area: length * width
 */

Inside the function:

1. Check if the length OR width is negative. If so, print "Error: impossible" and terminate the java program.

2. Then, calculate the area of the rectangle and return it.

/**
 * Name: areaRectangle
 * @param length (double).
 * @param width  (double).
 * @return the area (double)
 *
 * Inside the function:  <-----
 *  1. If the length OR width is negative
 *       - print "Error: impossible" and
 *       - terminate the program.
 *  2. return the area: length * width
 */

Task 3: area of a triangle

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$Area = base * height \div 2$

/**
 * Name: areaTriangle
 * @param base: (double).
 * @param height: (double).
 * @return the area (double)
 *
 * Inside the function:
 *  1. If the base OR height is negative
 *      - print "Error: impossible"
 *      - terminate the program.
 *  2. return the area: base * height / 2
 */

Task 4: area of a circle

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$Area = π * radius²$

How do you get PI? You could set a double equal to 3.14159... but, please don't do that. You can get PI from the Math class. I encourage you to look it up.

Then, write a function that calculates the area of a circle.

/**
 * Name: areaCircle
 * @param radius (double).
 * @return area (double)
 *
 * Inside the function:
 *  1. If the radius is negative
 *      - print: Impossible
 *      - terminates the program
 *  2. returns the area: π * radius2
 */

Task 5: Calculate the areas

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Using the appropriate function, calculate the area for:

• a square with a side of 2 cm.

• a rectangle with a length of 1 cm, and a width of 2 cm.

• a triangle with a base of 1 cm, and a height of 2 cm.

• a circle with a radius of 2 cm.

// double square = area of square with a side of 2.
// double rectangle = area of rectangle with length: 1, width: 2.
// double triangle = area of triangle with base: 1, height: 2.
// double circle = area of circle with a radius of 2.

Task 6: Write a function that prints every area

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Instead of cluttering main()with 4 println statements, write a function that prints every area.

/**
 * Name: printAreas -- it prints four areas
 * @param square (double)
 * @param rectangle (double)
 * @param triangle (double)
 * @param circle (double)
 *
 * Inside the function:
 *  1. print: ("Square area: <square area>")
 *  2. print: ("Rectangle area: <rectangle area>")
 *  3. print: ("Triangle area: <triangle area>")
 *  4. print: ("Circle area: <circle area>")
 *
 */

Task 7: Call the printAreas function.

---

From main(), call the printAreas function.

Run your code

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Thank you for using the area calculator
This calculator lets you get the area of:

1 -- Square
2 -- Rectangle
3 -- Triangle
4 -- Circle

Square area: 4.0
Rectangle area: 2.0
Triangle area: 1.0
Circle area: 12.5663706144

Good Luck!

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