Rectangle.java

import java.util.Scanner;

public class Rectangle {

    public static class Point {

        public float x, y;

        public Point(float x, float y) {
            this.x = x;
            this.y = y;
        }

        public Point shift(float dx, float dy) {
            this.x += dx;
            this.y += dy;
            return this;
        }

        @Override
        public String toString() {
            return x + ", " + y;
        }
    }
    public final Point topLeft, bottomRight;

    public Rectangle(Point topLeft, Point bottomRight) throws Exception {
        if(topLeft.x >= bottomRight.x || topLeft.y <= bottomRight.y) {
            throw new Exception("Illegal rectangle");
        }
        this.topLeft = topLeft;
        this.bottomRight = bottomRight;
    }

    public Rectangle unify(Rectangle other) throws Exception {
        float x0 = Math.min(topLeft.x, other.topLeft.x);
        float y0 = Math.max(topLeft.y, other.topLeft.y);
        float x1 = Math.max(bottomRight.x, other.bottomRight.x);
        float y1 = Math.min(bottomRight.y, other.bottomRight.y);
        return new Rectangle(new Point(x0, y0), new Point(x1, y1));
    }

    public boolean contains(Point p) {
        if (p.x >= topLeft.x && p.x <= bottomRight.x
                && p.y <= topLeft.y && p.y >= bottomRight.y) {
            return true;
        }
        return false;
    }

    public Rectangle shift(float dx, float dy) {
        topLeft.shift(dx, dy);
        bottomRight.shift(dx, dy);
        return this;
    }

    @Override
    public String toString() {
        return "Rect(" + topLeft.toString() + ", " + bottomRight.toString() + ")";
    }

    public Rectangle intersection(Rectangle other) throws Exception {
        float x0 = Math.max(topLeft.x, other.topLeft.x);
        float y0 = Math.min(topLeft.y, other.topLeft.y);
        float x1 = Math.min(bottomRight.x, other.bottomRight.x);
        float y1 = Math.max(bottomRight.y, other.bottomRight.y);
        return new Rectangle(new Point(x0, y0), new Point(x1, y1));
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws Exception {
        Scanner scanner = new Scanner(System.in);

        Rectangle r1 = inputRectangle(scanner);
        System.out.println("Rectangle 1: " + r1.toString());

        Rectangle r2 = inputRectangle(scanner);
        System.out.println("Rectangle 2: " + r2.toString());

        try {
            System.out.println("Unification: " + r1.unify(r2).toString());
        } catch (Exception e) {
            System.out.println("No unification");
        }

        try {
            System.out.println("Intersection: " + r1.intersection(r2).toString());
        } catch (Exception e) {
            System.out.println("No intersection");
        }

        System.out.print("Enter a point: ");
        Point p = new Point(scanner.nextFloat(), scanner.nextFloat());
        System.out.println("Point is" + (r1.contains(p) ? "" : " NOT") + " in rectangle 1");
        System.out.println("Point is" + (r2.contains(p) ? "" : " NOT") + " in rectangle 2");

        System.out.print("Enter a vector to shift: ");
        float dx = scanner.nextFloat();
        float dy = scanner.nextFloat();
        System.out.println("Result 1: " + r1.shift(dx, dy).toString());
        System.out.println("Result 2: " + r2.shift(dx, dy).toString());
    }

    private static Rectangle inputRectangle(Scanner scanner) throws Exception {
        System.out.println("Enter rectangle:");
        System.out.print("    top left point: ");
        float x0 = scanner.nextFloat();
        float y0 = scanner.nextFloat();

        System.out.print("    bottom right point: ");
        float x1 = scanner.nextFloat();
        float y1 = scanner.nextFloat();

        return new Rectangle(new Point(x0, y0), new Point(x1, y1));
    }
}