Article: The OOP has been explained wrongly to you

WashingMachine.java

class WashingMachine {
    private Integer temperature;
    private Integer spinSpeed;
    private Collection<LaundryElement> laundry;

    // constructor, getters and setters
  
    void wash() {
        laundry.forEach(laundryElement -> laundryElement.setDirty(false));
    }
}