You have been asked to design the architecture for a washing machine simulator. There are four types of washing machines: a basic washer a premium washer a deluxe washer a smart washer. All washing machines can wash clothes based on a setting selected by a user. A basic washer allows only soap powder to be added. A premium washer only allows liquid soap to be added. A deluxe washer uses only liquid soap but also allows fabric softener to be added and dispensed. A smart washer alerts the user when the wash cycle is finished via a message.

FIGURE 1

public interface WashingMachine{

boolean wash (int setting);

void addSoapPowder(Powder p);

void addLiquidSoap(LiquidSoap ls);

void addFabricSoftener(FabricSoftener fs);

Message alert( ); }

(a) Explain the problem with having the interface shown in Figure 1, to specify the behaviour for the four types of washing machines?

b) Which SOLID object-oriented design principle is violated in the interface shown in Figure 1?

(c) Suggest how the interface in Figure 1 can be refactored to adhere to the principles identified in part (b).

(d) Draw a UML class diagram to model a solution for the washing machine domain in the scenario based on your answers in part

(c)You may use the method signatures in Figure 1.

(e) A SencilloWasher is a basic washing machine that only uses soap powder. Draw a sequence diagram to illustrate the interaction between a user and SencilloWasher.