Question

Java Object Oriented

Create a class that models a rectangle located in the first Cartesian quadrant. The class should store information about a rectangle such that it can be drawn in an X,Y cartesian coordinate system, including rectangles which are not aligned parallel to the X-Y axes, that is, they are oriented making an angle with the X axis.

Your class should provide one constructor methods for specifying the rectangle The constructor should receive the rectangle area, the length of the long side, the angle that the long side makes with the X axis, and the coordinates for the vertex closer to the origin and the X-axis.

Your class should provide methods for (computing and) returning the area of the rectangle

Your class should provide methods for (computing and) returning the length of short and long side sides of the rectangle

Your class should provide methods for (computing and) returning the angle it's long side makes with the horizontal (x axis)

Your class should provide methods for (computing and) returning the coordinates for all the corners of the rectangle starting with the coordinate closer to the origin and traversing the rectangle in counter clockwise order.

Answer 1

public class Rectangle {

    private double area, longSide, angleX;
    private double lowerLeftX, lowerLeftY;

    // angle should be in radians
    public Rectangle(double area, double longSide, double angleX, double lowerLeftX, double lowerLeftY) {
        this.area = area;
        this.longSide = longSide;
        this.angleX = angleX;
        this.lowerLeftX = lowerLeftX;
        this.lowerLeftY = lowerLeftY;
    }

    double getArea() {
        return area;
    }

    double lengthShortSide() {
        return area/longSide;
    }

    double lengthLongSide() {
        return longSide;
    }

    Coordinate getLowerLeft() {
        return new Coordinate(lowerLeftX, lowerLeftY);
    }

    Coordinate getLowerRight() {

        double width = Math.cos(angleX) * longSide;
        double height = Math.sin(angleX) * longSide;

        return new Coordinate(lowerLeftX + width, lowerLeftY + height);
    }

    Coordinate getUpperLeft() {
        double shortSide = lengthShortSide();
        double width = Math.cos(Math.PI/2 - angleX) * shortSide;
        double height = Math.sin(Math.PI/2 - angleX) * shortSide;

        return new Coordinate(lowerLeftX - width, lowerLeftY + height);
    }

    Coordinate getUpperRight() {
        double shortSide = lengthShortSide();
        Coordinate lowerRight = getLowerRight();

        double angle = Math.PI/2 - angleX;

        double width = Math.cos(angle) * shortSide;
        double height = Math.sin(angle) * shortSide;

        return new Coordinate(lowerRight.x - width, lowerRight.y + height);
    }

}

class Coordinate {
    double x, y;

    public Coordinate(double x, double y) {
        this.x = x;
        this.y = y;
    }

    @Override
    public String toString() {
        return "Coordinate [x=" + x + ", y=" + y + "]";
    }   
}

====================================================================

import java.awt.Graphics;

import javax.swing.JComponent;
import javax.swing.JFrame;

public class RectangleDemo extends JComponent {

    private static final long serialVersionUID = 1L;

    public void paintComponent(Graphics g) {
        Rectangle r = new Rectangle(20000, 120, Math.PI / 6, 120, 60);

        Coordinate lowerLeft = r.getLowerLeft();
        Coordinate lowerRight = r.getLowerRight();
        Coordinate upperLeft = r.getUpperLeft();
        Coordinate upperRight = r.getUpperRight();

        System.out.println(lowerLeft);
        System.out.println(lowerRight);
        System.out.println(upperLeft);
        System.out.println(upperRight);
        drawLine(g, lowerLeft.x, lowerLeft.y, lowerRight.x, lowerRight.y);
        drawLine(g, upperRight.x, upperRight.y, lowerRight.x, lowerRight.y);
        drawLine(g, upperRight.x, upperRight.y, upperLeft.x, upperLeft.y);
        drawLine(g, lowerLeft.x, lowerLeft.y, upperLeft.x, upperLeft.y);
    }

    void drawLine(Graphics g, double x, double y, double x2, double y2) {
        g.drawLine((int) x, (int) y, (int) x2, (int) y2);
    }

    public static void main(String args[]) {
        RectangleDemo panel = new RectangleDemo();

        // frame to hold the panel
        JFrame application = new JFrame();

        // set frame to exit on close
        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        application.add(panel);
        application.setSize(500, 500);
        application.setVisible(true);
    }
}

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