day 13 oop additional

public class Day13A {

    public static void main(String[] args) {
        Rectangle callRect = new Rectangle(7, 4.32);

        System.out.println("length: 7");
        System.out.println("width: 4.32");
        System.out.printf("Area: " + callRect.getArea());

        Rectangle callRect2 = new Rectangle();
        callRect2.setLen(8);
        callRect2.setWid(6.44);

        System.out.println("length: 8");
        System.out.println("width: 6.44");
        System.out.printf("Area: " + callRect2.getArea());


        Box callBox = new Box(4,7,3);
        System.out.println("length: 4");
        System.out.println("width: 7");
        System.out.println("height: 3");
        System.out.printf("Volume: " + callBox.getBoxVolume());
        System.out.printf("%nSurface Area: " + callBox.getSurfaceArea());
    }

}

class Rectangle {
    private double len; //set
    private double wid; //set
    private double area; //get

// - Encapsulation
    public void setLen(double len) {
        this.len = len;
    }

    public void setWid(double wid) {
        this.wid = wid;
    }

    public double getLen() {
        return len;
    }

    public double getWid() {
        return wid;
    }

    public double getArea() {
        area = computeArea(getLen(), getWid());
        return area;
    }

// - Constructor
    public Rectangle() {
    }

    public Rectangle(double ln, double wd) {
        this.len = ln;
        this.wid = wd;
    }

    double computeArea(double ln, double wd) {
        double ar = ln * wd;

        return ar;
    }
}

class Box extends Rectangle {
    private double hei; //set
    private double boxVolume; //get
    private double surfaceArea; //get

// - Encapsulation
    public void setHei(double hei) {
        this.hei = hei;
    }

    public double getHei() {
        return hei;
    }

    public double getBoxVolume() {
        boxVolume = computeVolume(getLen(), getWid(), getHei());
        return boxVolume;
    }

    public double getSurfaceArea() {
        surfaceArea = computeSurfaceArea(getLen(), getWid(), getHei());
        return surfaceArea;
    }

// - Constructor
    public Box() {
    }

    public Box(double ln, double wd, double hi) {
        super(ln, wd);
        this.hei = hi;
    }

    private double computeVolume(double ln, double wd, double hi) {
        double vol = computeArea(ln, wd) * hi;

        return vol;
    }

    private double computeSurfaceArea(double ln, double wd, double hi) {
        double sArea = 2 * (computeArea(ln, wd) + computeArea(ln, hi) + computeArea(hi, wd));

        return sArea;
    }
}