public class Point2D {

private int x; // x-coordinate private int y; // y-coordinate

public int getX() { return x; }

public int getY() { return y; }

public void setX(int x) { this.x = x; }

public void setY(int y) { this.y = y; } public void resetToOrigin() { this.x=0; this.y=0; } public void translate(int dx,int dy) { this.x+=dx; this.y+=dy; } @Override public String toString() { return "(" + x + ","+ y + ')'; }

public boolean equals(Point2D that) { if (that == null) { return false; } if (getClass() != that.getClass()) { return false; } final Point2D other = (Point2D) that; if (this.x != other.x) { return false; } if (this.y != other.y) { return false; } return true; } public static void main(String[] args) { Point2D a= new Point2D(); a.setX(5); a.setY(2); System.out.println("Point2D at ("+a.getX()+", "+a.getY()+")"); a.translate(-1, -1); System.out.println("Point2D at ("+a.getX()+", "+a.getY()+")"); a.resetToOrigin(); System.out.println("Point2D at ("+a.getX()+", "+a.getY()+")"); Point2D b=new Point2D(); Point2D c=new Point2D(); System.out.println(b.toString()); System.out.println(c);//because we have override the to string method in the point class System.out.println("Are b ans c equal: "+b.equals(c)); } }

Class Invariants

• The start and end points of a line segment should never be null
  • Initialize these to the origin instead.

Data

• A LineSegment has a start point
  • This is a Point2D object
  • All data will be private
• A LineSegment also has an end point.
  • Also a Point2D object

Methods

• Create getters and setters for your start and end points
  • public Point2D getStartPoint() {
  • public void setStartPoint(Point2D start) {
• Create a toString() function to build a string composed of the startPoints toString() and endPoints toString()
  • Should look like Line start(0,0) and end(1,1)
• Create an equals method that determines if two LineSegments are equal
  • public boolean equals(Object other) {
    • if(other == null || !(other instanceof LineSegment)) return false; //use this as the first line
    • LineSegment that = (LineSegment) other; //after this line, use this v.s. that
    • //return start and end points are equal, requires an equals in the Point2D class
• Uncomment the method call in ClassDesignIIDriver.java to invoke the driver associated with the LineSegment code.
  • Fix each error as you encounter them in the driver for LineSegment
• Create a default, no-arg constructor
  • This should define the start point and the end point to be at the origin
• Create an overloaded constructor that takes a start point and an end point
  • This should check for nulls for the start and end point
• Create a copy constructor (also overloaded) that takes a LineSegment object and initializes this using other.
  • public LineSegment(LineSegment other) {
• Create a distance() function that will calculate the line distance using the distance formula
  • Hint: Math.sqrt(), Math.abs()
• Run the driver code in ClassDesignIIDriver.java to test your LineSegment class.
• Answer the following questions as comments in your LineSegment code:
  • What is a privacy leak?
  • Do your getters or setters have privacy leaks?
  • Where else could a privacy leak occur?