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/*
Welcome back CS02 students

please log in to your VM
https://vm.ktbyte.com
username: 16fa + ktbyte_username
password: ktbyte

Today's lesson: inheritance review, interfaces

*/
import java.util.*;

// public class is a class that is visible to other files
public class Lesson4 {
  // a public function/method is something that can be
  // accessed outside of the class
  public static void main(String[] args) {
    Point p = new Point(2, 5);
    System.out.println(p.getX());
    System.out.println(Point.getCount()); // static function

    Point p2 = new LabeledPoint(-5, 10, "KTByte office");
    System.out.println(p2.getX()); // -5
    System.out.println(Point.getCount()); // 2

    // Object class has a toString() that you can override
    // to change what this displays
    System.out.println(p); //
    System.out.println(p2); // (-5, 10)

    // also look up: boolean equals(Object o) inside Object

    Point[] points = {p, p2, new Point(3, -4)};
    System.out.println(Arrays.toString(points));
    Arrays.sort(points); // sort based on the compareTo method
    System.out.println(Arrays.toString(points));
  }
}

// we cannot access private functions/variable inside Point
class LabeledPoint extends Point {
  private String label;

  public LabeledPoint(int x, int y, String label) {
    super(x, y); // calls the super classes' constructor
    this.label = label;
  }

  public String toString() {
    return label + ": " + super.toString();
  }
}

// represents a point on a 2D plane
// once a Point is created, its x y values cannot be modified
class Point implements Comparable<Point> {
  // private means classes outside of Point
  // cannot access it
  private int x;
  private int y;

  // counts the number of Point objects created
  // static means the variable is shared across all Point object
  private static int count = 0;

  // static function can be called without a Point object
  public static int getCount() {
    return count;
  }

  // force it so that when you create a Poitn object
  // you have to set x and y
  public Point(int x, int y) {
    // "this" means the current object
    this.x = x;
    this.y = y;
    count++;
  }

  public int getX() {
    return x;
  }

  public int getY() {
    return y;
  }

  public String toString() {
    return "(" + x + ", " + y + ")";
  }

  // look up: Comparable
  // point with a  lower x value comes first
  public int compareTo(Point p) {
    return x - p.x;
  }
}