Java

OOP GUIDE / WORK

LINE CLASS SOLUTIONS

TASK – PART 1 – BASIC LINE CLASS

Here is my solution:

public class Line

{

public double x1, y1;

public double x2, y2;

public Line(double tx1, double ty1, double tx2, double ty2)

{

x1 = tx1;

y1 = ty1;

x2 = tx2;

y2 = ty2;

}

public double length()

{

double dx = x2 - x1;

double dy = y2 - y1;

return Math.sqrt(dx * dx + dy * dy);

}

public String toString()

{

return "(" + x1 + "," + y1 + ") to (" + x2 + "," + y2 + ") [length="+ length() + "]";

}

}

TASK – PART 2 – ARRAYLIST

Here is my solution:

import java.util.ArrayList;

import java.util.Collections;

public class LineTester

{

public static void main(String[] args)

{

ArrayList<Line> al = new ArrayList<Line>();

al.add(new Line(4,2,9,0));

al.add(new Line(2,9,1,8));

al.add(new Line(0,2,7,8));

al.add(new Line(4,4,5,5));

al.add(new Line(2,4,0,5));

for (int i=0; i<al.size(); i++)

{

System.out.println(al.get(i));

}

}

}

TASK – PART 3 – IMPLEMENT COMPARABLE

Here is my solution:

public class Line implements Comparable

{

public double x1, y1;

public double x2, y2;

public Line(double tx1, double ty1, double tx2, double ty2)

{

x1 = tx1;

y1 = ty1;

x2 = tx2;

y2 = ty2;

}

public double length()

{

double dx = x2 - x1;

double dy = y2 - y1;

return Math.sqrt(dx * dx + dy * dy);

}

public String toString()

{

return "(" + x1 + "," + y1 + ") to (" + x2 + "," + y2 + ") [length="+ length() + "]";

}

@Override

public int compareTo(Object o)

{

Line other = (Line)o;

if (this.length() < other.length())

{

return -1;

}

else if (this.length() == other.length())

{

return 0;

}

else

{

return 1;

}

}

}

TASK – PART 4 – SORTING

Here is my solution:

import java.util.ArrayList;

import java.util.Collections;

public class LineTester

{

public static void main(String[] args)

{

ArrayList<Line> al = new ArrayList<Line>();

al.add(new Line(4,2,9,0));

al.add(new Line(2,9,1,8));

al.add(new Line(0,2,7,8));

al.add(new Line(4,4,5,5));

al.add(new Line(2,4,0,5));

for (int i=0; i<al.size(); i++)

{

System.out.println(al.get(i));

}

Collections.sort(al);

System.out.println("=====");

for (int i=0; i<al.size(); i++)

{

System.out.println(al.get(i));

}

}

}

Here is some sample output from the code above:

(4.0,2.0) to (9.0,0.0) [length=5.385164807134504]

(2.0,9.0) to (1.0,8.0) [length=1.4142135623730951]

(0.0,2.0) to (7.0,8.0) [length=9.219544457292887]

(4.0,4.0) to (5.0,5.0) [length=1.4142135623730951]

(2.0,4.0) to (0.0,5.0) [length=2.23606797749979]

=====

(2.0,9.0) to (1.0,8.0) [length=1.4142135623730951]

(4.0,4.0) to (5.0,5.0) [length=1.4142135623730951]

(2.0,4.0) to (0.0,5.0) [length=2.23606797749979]

(4.0,2.0) to (9.0,0.0) [length=5.385164807134504]

(0.0,2.0) to (7.0,8.0) [length=9.219544457292887]