Adding Controls to classes in Java

Question

So I created a class of Rect which just has the properties of rectangle. How would I add an implementation so that the width and length must be integers greater than zero or if a given number is negative it will instead take absolute value. I have not used java in years and my experience with it is limited so any advice would help.

public class Rect {

    int x;
    int y;
    int width;
    int length;

    public int getPerimeter() {
        return (2 * width) + (2 * length);
    }

    public int getArea() {
        return width * length;
    }

    public void move(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public void changeSize(int n) {
        this.width = n;
        this.length = n;
    }

    public void print(int area, int perimeter) {
        System.out.printf("X: %d\n", this.x);
        System.out.printf("Y: %d\n", this.y);
        System.out.printf("Length: %d\n", this.width);
        System.out.printf("Width: %d\n", this.length);
        System.out.printf("Area: %d\n", area);
        System.out.printf("Perimeter: %d", perimeter);
    }

    public static void main(String[] args) {
        Rect r1 = new Rect();
        r1.length = 1;
        r1.width = 2;
        r1.x = 3;
        r1.y = 4;

        //test here
        int area = r1.getArea();
        int perimeter = r1.getPerimeter();

        r1.print(area, perimeter);

    }
}

I haven't really tried much as I am confused to where I should write the appropriate code.

Answer 1

To get the absolute values of negatives, you can replace this.width = width; with this.width = Math.abs(width); and the same for length and any other variables that cannot be negative.