Lab 15: Methods, Drawing and Style
Objectives
-
Practice writing and calling
voidmethods that take parameters. -
Following coding standards.
-
Using Checkstyle to check coding standards.
Key Terms
- parameter (or formal parameter)
- A variable declared inside the parentheses of a method header.
- argument (or actual parameter)
- A value passed to a method at the time the method is called. The value will be assigned to the parameter variable.
Part 1: Drawing Pictures
For this activity we will make use of the StdDraw class developed by Robert Sedgewick and Kevin Wayne at Princeton University. This class provides a set of methods that make it possible to create simple drawings in Java.
You can find the complete documentation online, but today we will only be working with the following methods:
| Modifier and Type | Method and Description |
|---|---|
static void |
circle(double x, double y, double radius)
Draws a circle of the specified radius, centered at (x, y).
|
static void |
filledCircle(double x, double y, double radius)
Draws a filled circle of the specified radius, centered at (x, y).
|
static void |
rectangle(double x, double y, double halfWidth, double halfHeight)
Draws a rectangle of the specified size, centered at (x, y).
|
static void |
filledRectangle(double x, double y, double halfWidth, double halfHeight)
Draws a filled rectangle of the specified size, centered at (x, y).
|
static void |
line(double x0, double y0, double x1, double y1)
Draws a line segment between (x0, y0) and (x1, y1).
|
- Create a folder to contain your work for today's activity.
- Copy the following files into your folder:
- Open
DrawDemo.javain jGRASP. Take a minute to read over the code, then compile and execute it. - By default, (0, 0) is located in the lower-left corner of the StdDraw drawing window and (1, 1) is in the upper-right. Modify
DrawDemo.javato place a small filled rectangle in the upper-left corner of the drawing window. Test your modifications.
Part 2: Drawing Houses
- Open
Houses.javausing jGRASP. Take a minute to read over the provided code, then try running it. - Add a new method named
drawHousethat satisfies the following requirements:- It should take two
doubleparameters namedxandy. - When executed, it should draw a house that looks like the following:
- The total width of the house should be .2.
- The total height of the house should be .3. The rectangle at the bottom should have a height of .2 and the roof should have a height of .1.
- The rectangle that forms the bottom part of the house should be centered at (x, y). I.e. the location of the house should be determined by the parameter values.
- The method should include a call to
drawDoor. YOU SHOULD NOT COPY THE CONTENTS OFdrawDoorINTOdrawHouse!
- It should take two
-
Modify your
mainso that in includes three calls todrawHouse. Houses should be drawn at (.2, .5), (.5, .5) and (.8, .5). The result should look like the following:
- For your submission do a File - Save and save the drawing as house.jpg
Part 3: Style
Make any necessary modifications to ensure that your finished program conforms to the style guide from Lab3.
Part 4: Checkstyle
Follow the instructions on the Checkstyle lab page to run Checkstyle on Houses.java. Fix any style issues that are flagged.
Part 5: Submitting
In order to complete this lab you need to:
- Save a copy of the image generated by your completed
Houses.java. You can save the image through the file menu of the StdDraw drawing window. The file name should be "houses.jpg". - Upload a zip file called lab15.zip containing your
Houses.javaand houses.jpg file through https://autolab.cs.jmu.edu Autolab is configured to run Checkstyle. In order to get full credit, your submission will need to pass all of the formatting tests along with compiling and checking the diff on your output.
Acknowledgements: This lab was originally developed by Nathan Sprague.