Question

Suppose we have a class Rectangle and a class Square. Which should inherit from the other? Defend your answer by discussing the class invariants as well as (at least) one example method and its preconditions and postconditions.

Answer 1

Square class can inherit from the rectangle class.

Example code:

public class Main
{
   public static void main(String[] args) {
   Rectangle rectangle = new Rectangle(4, 6);
System.out.println(rectangle);
Square square = new Square(4);
System.out.println(square);
   }
}

class Rectangle {

private final int width;
private final int height;

public int getWidth() {
return width;
}

public int getHeight() {
return height;
}

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

public Rectangle(int width, int height) {
this.width = width;
this.height = height;
}

@Override
public String toString() {
return "This " + this.getClass().getSimpleName() + " has an area of " + getArea();
}

}
// Square is sub class inherting from rectangle class
class Square extends Rectangle {

public Square(int width) {
super(width, width);
}

@Override
public String toString() {
return super.toString();
}

}

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