Class Line

java.lang.Object

Line

Direct Known Subclasses:

LineSegment

public class Line
extends java.lang.Object

Author:

Sameh Fakhouri A line is specified by an equation:

y = mx + b

Where:

• m = The slope of the line
• b = The y intercept of the line

Field Summary

Fields

Modifier and Type	Field and Description
private double	slope A double value specifying the slope of the line.
private double	yIntercept A double value specifying the y intercept of the line.

Constructor Summary

Constructors

Constructor and Description
Line(double slope, double yIntercept) Constructor that accepts the slope and y intercept of the line.
Line(Point p1, Point p2) Constructor that accepts two Points specifying a line segment on the line.

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object object) Method to compare 'this' line for equality with the 'object' specified as a parameter.
double	getSlope() A getter for the slope of the line.
double	getyIntercept() A getter for the y intercept of the line.
Point	intersection(Line line) A method that computes and returns the Point intersection of 'this' line and the line specified in the parameter.
boolean	isParallelTo(Line line) This method tests 'this' line and the 'line' specified as a parameter for being parallel.
boolean	isPerpendicularTo(Line line) This method tests 'this' line and the 'line' specified as a parameter for being perpendicular.
boolean	pointIsOnTheLine(Point p) This method is called to find if the specified Point lies on 'this' line.
void	setSlope(double slope) A setter for the slope of the line.
void	setyIntercept(double yIntercept) A setter for the y intercept of the line.
java.lang.String	toString() Method to render 'this' instance of the Line class into a String.
void	updateLine(Point p1, Point p2) This method accepts two Points specifying a line segment on the line.

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

slope

private double slope

A double value specifying the slope of the line.

yIntercept

private double yIntercept

A double value specifying the y intercept of the line.

Constructor Detail

Line

public Line(double slope,
            double yIntercept)

Constructor that accepts the slope and y intercept of the line.

Parameters:

slope - A double value specifying the slope of the line.

yIntercept - A double value specifying the y intercept of the line.

Line

public Line(Point p1,
            Point p2)

Constructor that accepts two Points specifying a line segment on the line. Using these two Points, both the slope and the y intercept may be calculated by the constructor.

Parameters:

p1 - A Point specifying the first endpoint of the line segment

p2 - A Point specifying the second endpoint of the line segment

Method Detail

updateLine

public void updateLine(Point p1,
                       Point p2)

This method accepts two Points specifying a line segment on the line. This method is called to update the Line when the two points identifying the subclass LineSegment, change. This method will recompute the slope and the y intercept.

Parameters:

p1 - A Point specifying the first endpoint of the line segment

p2 - A Point specifying the second endpoint of the line segment

getSlope

public double getSlope()

A getter for the slope of the line.

Returns:

A double value representing the slope of the line

setSlope

public void setSlope(double slope)

A setter for the slope of the line.

Parameters:

slope - A double value representing a new slope for the line.

getyIntercept

public double getyIntercept()

A getter for the y intercept of the line.

Returns:

A double value representing the y intercept of the line

setyIntercept

public void setyIntercept(double yIntercept)

A setter for the y intercept of the line.

Parameters:

yIntercept - A double value representing a new slope for the line.

isParallelTo

public boolean isParallelTo(Line line)

This method tests 'this' line and the 'line' specified as a parameter for being parallel. Please note that two lines are parellel when they have the same slope and different y intercepts.

Parameters:

line - The Line we are testing for being parallel to 'This' line.

Returns:

Returns true if 'this' line is parallel to the specified line. Returns false otherwise.

isPerpendicularTo

public boolean isPerpendicularTo(Line line)

This method tests 'this' line and the 'line' specified as a parameter for being perpendicular. Please note that two lines l1 and l2 are perpendicular when the slope m1 = -(1/m2), where m1 and m2 are the slopes of lines l1 and l2 respectively.

Parameters:

line - The Line we are testing for being perpendicular to 'This' line.

Returns:

Returns true if 'this' line is perpendicular to the specified line. Returns false otherwise.

intersection

public Point intersection(Line line)

A method that computes and returns the Point intersection of 'this' line and the line specified in the parameter. Please note that parallel and equal lines do not have a Point of intersection.

Parameters:

line - The line for which we are computing the intersection with 'this' line.

Returns:

An instance of the Point class which represents the intersection of 'this' line and the one specified as a parameter. If no intersection exists, return null

pointIsOnTheLine

public boolean pointIsOnTheLine(Point p)

This method is called to find if the specified Point lies on 'this' line.

Parameters:

p - The point we are checking to see if it lies on the 'this' line.

Returns:

Returns true if the specified Point lies on 'this' line. Returns false otherwise.

equals

public boolean equals(java.lang.Object object)

Method to compare 'this' line for equality with the 'object' specified as a parameter.

Overrides:

equals in class java.lang.Object

Parameters:

object - An Object to be tested for equality with 'this' line

Returns:

Returns true if the specified 'object' is a Line with the same slope and y intercept as 'this' line. Returns false otherwise.

toString

public java.lang.String toString()

Method to render 'this' instance of the Line class into a String.

Overrides:

toString in class java.lang.Object

Returns:

Returns the string "Y = " + this.slope + " * X + " + this.yIntercept