Question

my question is on a java program. i have added all instructions for this homeowrk assignment. from how the input is entered and what the output should read. im seeing if i can get a psuedo code setup for how the algorithm should be setup.

Build an Intersection Check program. User inputs two points as x-y coordinates in twodimension space. Two points represent two end points of a line segment. Then, user can input second two points for the second line segment. With the two line segments, the program checks whether or not the two line segments intersect. The program displays “1” if the two line segments are crossing. Otherwise, display “0”. Please implement your algorithm in Java but not use API. Hint: use slop and intercept

Input: Four x-y coordinates that represent two point for the first line segment and two points for the second line segments

Output: 0 or 1 that represents intersection or no intersection

Example Input: 7 8 5 12 10 10 3 10

Output: 1 Do you want to test again? Y

Input: 5 10 5 2 2 1 8 7 Output: 1

Do you want to test again? Y

Input: 10 10 3 10 6 3 6 6 Output: 0

Do you want to test again? Y

Input: 5 4 8 6 10 6 5 1 Output: 0

Do you want to test again? N

Thank you!

need help with this java program. any help out there

Answer 1

/**
 * @fileName LineIntersect.java
 * @author 
 * @since 4/2/17
 */


package lineintersect;

import java.util.Scanner;

public class LineIntersect {

    static Point p = new Point();

    /**
     * Calculating distace Between two points
     * @param a Point
     * @param b Point
     * @return  distance
     */
    public static double distance(Point a, Point b) {
        return Math.sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
    }

    /**
     *This method will tell point c is in between a and b or not
     * @param a Point
     * @param b Point
     * @param c Point
     * @return True/False
     */
    public static boolean isBetween(Point a, Point b, Point c) {
        return distance(a, c) + distance(c, b) == distance(a, b);
    }

    public static void intersectionWithVerticalLine(Line l, float x) {
        p.y = l.m * x + l.c;
        p.x = x;
    }

    /**
     * This function finds the intersection point of a line when m!=infinite
     * @param l1 First line
     * @param l2 Second Line
     */
    public static void normalIntersection(Line l1, Line l2) {

        float x = (l2.c - l1.c) / (l1.m - l2.m);
        float y = l1.c + ((l2.c - l1.c) * l1.m / (l1.m - l2.m));
        p.x = x;
        p.y = y;

    }


    public static int getIntersectionPoint(Line l1, Line l2) {

        if (l1.p1.x == l1.p2.x) {
            intersectionWithVerticalLine(l2, l1.p1.x);
        } else if (l2.p1.x == l2.p2.x) {
            intersectionWithVerticalLine(l1, l2.p1.x);
        } else {
            normalIntersection(l1, l2);
        }
        if (isBetween(l1.p1, l1.p2, p) && isBetween(l2.p1, l2.p2, p)) {

            return 1;
        } else {
            return 0;
        }

    }


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        while (true) {
            System.out.println("Enter the Points");
            System.out.print("Input:");
            float x1 = sc.nextFloat();
            float y1 = sc.nextFloat();
            float x2 = sc.nextFloat();
            float y2 = sc.nextFloat();
            float x3 = sc.nextFloat();
            float y3 = sc.nextFloat();
            float x4 = sc.nextFloat();
            float y4 = sc.nextFloat();

            Point p1 = new Point(x1, y1);
            Point p2 = new Point(x2, y2);
            Point p3 = new Point(x3, y3);
            Point p4 = new Point(x4, y4);

            Line l1 = new Line(p1, p2);
            Line l2 = new Line(p3, p4);
            System.out.print ("  Output:" + LineIntersect.getIntersectionPoint(l1, l2));
            System.out.println();
            System.out.println("Do you want to test again?");
            char s = sc.next().charAt(0);
            if (s == 'N' || s == 'n') {
                break;
            }


        }

    }

}

class Line {

    Point p1;
    Point p2;
    float m;
    float c;

    /**
     * This is parametrized constructor to initialize a Line instance
     * @param p1 Point
     * @param p2 Point
     */
    public Line(Point p1, Point p2) {
        this.p1 = p1;
        this.p2 = p2;
        getSlop();
        getIntercept();
    }


    /**
     *calculating the slop m  for this line
     */
    private void getSlop() {
        if (p2.y == p1.y) { //if y2-y1 ==0 menas slop is  0  line is a horizontal line
            this.m = 0;
        } else if (p1.x != p2.x) {
            this.m = (p2.y - p1.y) / (p2.x - p1.x);  // calculating sloap using formula (y2-y1)/(x2-x1)
        }
    }

    private void getIntercept() {


        //if  x1 and x2 are equals then slop will be infinite so then we line of  equation  will be x= some value
        if (p1.x != p2.x) {

            //if slop of line  m is 0 then  intercept will be y1 or y2 because they  are equal thats why m is 0
            if (m == 0) {
                this.c = p1.y;

            } else {

                //calculating intercept by putting x y and m value in equation of line  y=mx +c => c= y-mx
                this.c = p1.y - m * p1.x;

            }
        }
    }

    @Override
    public String toString() {
        return "Line{" +
                "y=" + m + "x +" + c + '}' + p1.toString() + " " + p2.toString();
    }
}

class Point {
    float x;
    float y;

    /**
     * This is parametrized constructor which initialize Point
     * @param x
     * @param y
     */
    public Point(float x, float y) {
        this.x = x;
        this.y = y;
    }

    /**
     * Default constructor
     */
    public Point() {

    }

    @Override
    public String toString() {
        return "Point{" +
                "x=" + x +
                ", y=" + y +
                '}';
    }
}

output:

Enter the Points Input:7 8 5 12 10 10 3 10 Output:1 Do you want to test again? Enter the Points Input:5 10 5 2 2187 Output:1 Do you want to test again? Enter the Points Input:10 10 3 10 6 36 6 Output:0 Do you want to test again? Enter the Points Input:5 486 10 6 5 1 Output : θ Do you want to test again? Process finished with exit code