This assignemnt is super easy if you know java. You will need is to add any fields that are required for the class to work properly and fill in definitions for the given methods. Just follow the instructions provided in the attached file. I can email you the test file afterwards.

Files to submit

SlopeInterceptLE.java

Define a class to model a linear equation of variables x and y in slope intercept form. A skeleton for this file is provided in the project pack.

SlopeInterceptLETests.java

Provides tests of the correctness of the above class.

3.1 Good old Em ex plus Bee

A linear equation is in slope intercept form if it is written

y=mx+b

where m and b are constants that do not change while x and y are variables that do change.

Define a class which models a linear equation in slope intercept form. A template is provided for you in the fileSlopeInterceptLE.java. You will need to add any fields that are required for the class to work properly and fill in definitions for the below methods.

3.2 Class Structure of SlopeInterceptLE

// A class to model linear equations of two variable (x and y) in
// slope intercept form.

public class SlopeInterceptLE {

// Public constructor that accepts values for the slope m and
// intercept b, defaults the value of x to 0.0 and sets y
// appropriately.

publicSlopeInterceptLE(double m, double b);

// Public constructor that accepts values for the slope m and
// intercept b and initial value of x and sets y appropriately.

publicSlopeInterceptLE(double m, double b, double x);

// Return the numeric value of the equation which is the numeric
// quantity that should be on both left and right sides of the equal
// sign.

public double value();

// Return the current value of x

public double getX();

// Return the current value of y

public double getY();

// Set the value of x and change y accordingly to preserve the
// equation.

public void setX(double x);

// Set the value of $y$ and change $x$ accordingly to preserve the
// equation.

public void setY(double y);

// Return a =String= version of the general form of the equation.
// The pretty version's general format should be as follows.
// y = M.MM * x + B.BB
// M.MM is the slope with 2 digits of accuracy and B.BB is the
// intercept with two digits of accuracy. Look for a method of the
// String class to assist with formatting.
// Examples:
// y = 1.23 * x + 122.41
// y = -1.23 * x + -122.41

public String toString();

}

3.3 Implementation Notes

The method

public String toString()

should return a String version of the general form of the equation. This string's general format should be

y = M.MM * x + B.BB

where M.MM is replaced with the value of m with 2 decimal digits of accuracy and similarly for B.BB being replaced by b. For example, if m=1.23,b=122.408, the appropriate string to produce is

y = 1.23 * x + 122.41

If m=-1.23,b=-122.408, the appropriate string to produce is

y = -1.23 * x + -122.41

This task is significantly easier if you examine the String.format() method and learn a few things about format strings for producing nice looking output. Format strings are used with System.out.printf() which is derived from the C language printf function. There are several places to learn about them.

3.4 Sample Session

Welcome to DrJava. Working directory is /...

>SlopeInterceptLEsi = new SlopeInterceptLE(1.0,2.0)
>si
y = 1.00 * x + 2.00
>si.toString()
y = 1.00 * x + 2.00
>si.getX()
0.0
>si.getY()
2.0
>si.value()
2.0
>si.setX(4)
>si.value()
6.0
>si.getY()
6.0
>si
y = 1.00 * x + 2.00
>si.toString()
y = 1.00 * x + 2.00
>si = new SlopeInterceptLE(0.25, 10.25, 1.0);
>si.getX()
1.0
>si.getY()
10.5
>si
y = 0.25 * x + 10.25
>si.setY(4.5)
>si.getY()
4.5
>si.getX()
-23.0
>si
y = 0.25 * x + 10.25
>si.value()
4.5
>si = new SlopeInterceptLE(-0.25, -10.25, -1.0);
>si.toString()
y = -0.25 * x + -10.25
>si = new SlopeInterceptLE(0.67512, -1.999, -1.0);
>si.toString()
y = 0.68 * x + -2.00