/*
* A very simple example of implementing the comparable interface
* The class below implements a Rectangle that is comparable with
* other rectangles by its area. 
*
* @author gtowell
* created: August 6, 2021
*/
public class CompExRect implements Comparable<CompExRect> {
    // the width and height -- may not be changed and must be set
    private final int width, height;

    // Constructor to set the width and height
    public CompExRect(int w, int h) {
        width = w;
        height = h;
    }

    /*
    * The Area
    * @return the area
    */
    public int area() {
        return width * height;
    }

    @Override
    public int compareTo(CompExRect cer) {
        // Just subtract one area from the other
        //compareTo only care about the sign of the result, not the magnitude
        if (cer == null)
            return 1; // annoyingly, null can sneak in here so it needs to be handled
        return this.area() - cer.area();
    }

    @Override 
    public String toString() {
        return "<<L:" + width + " W:" + height+">>";
    }

    public static void main(String[] args) {
        // Array of objects to be compared
        // Watch out for null
        CompExRect[] ce = { new CompExRect(3,4),  new CompExRect(5, 2), new CompExRect(11, 1), new CompExRect(1, 7), null };
        for (int i = 0; i < ce.length - 1; i++) {
            for (int j = i + 1; j < ce.length; j++) {
                System.out.println(ce[i] + " " + ce[j] + " " + ce[i].compareTo(ce[j]));
            }
        }
        //The next line will not compile as compareTo is only defined for comparing this class
        //System.out.println(ce[0].compareTo("cer"));
    }
    
}