Interview questions-Microwave

Food.java

public class Food {
	private String name = "";
	private boolean shell = false;
	private boolean skin = false;
	
	public Food(String name) {
		super();
		setName(name);
	}
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public boolean isShell() {
		return shell;
	}
	
	public void setShell(boolean shell) {
		this.shell = shell;
	}
	
	public boolean isSkin() {
		return skin;
	}
	
	public void setSkin(boolean skin) {
		this.skin = skin;
	}
}

Heating.java

public interface Heating {
	public void start(Food food) throws Exception;
}

Microwave.java

public interface Microwave {
	public boolean open();
	public boolean putFood(Food food);
	public Food getFood();
	public boolean close();
	public boolean startHeating();
}

MicrowaveContext.java

public class MicrowaveContext {
	private MicrowaveState state = null;
	
	public MicrowaveContext(MicrowaveState state){
		this.state = state;
	}

	public void setState(MicrowaveState state) {
		this.state = state;
	}

	public void push() {
		state.push(this);
	}

	public void pull(){
		state.pull(this);
	}
	
	public boolean canOpen(){
		return state.canOpen();
	}
	
	public boolean canClose(){
		return state.canClose();
	}
	
	public boolean canPutFood(){
		return state.canPutFood();
	}
	
	public boolean canGetFood(){
		return state.canGetFood();
	}
	
	public boolean canHeating(){
		return state.canHeating();
	}
}

MicrowaveState.java

public interface MicrowaveState {
	public void push(MicrowaveContext c);
	public void pull(MicrowaveContext c);
	public boolean canOpen();
	public boolean canClose();
	public boolean canPutFood();
	public boolean canGetFood();
	public boolean canHeating();
}

MicrowaveStepFive.java

public class MicrowaveStepFive implements MicrowaveState {

	@Override
	public void push(MicrowaveContext c) {
		c.setState(new MicrowaveStepOne());
	}

	@Override
	public void pull(MicrowaveContext c) {
		c.setState(new MicrowaveStepFour());
	}

	@Override
	public boolean canOpen() {
		return false;
	}

	@Override
	public boolean canClose() {
		return false;
	}

	@Override
	public boolean canPutFood() {
		return false;
	}

	@Override
	public boolean canGetFood() {
		return false;
	}

	@Override
	public boolean canHeating() {
		return false;
	}

}

MicrowaveStepFour.java

public class MicrowaveStepFour implements MicrowaveState {

	@Override
	public void push(MicrowaveContext c) {
		c.setState(new MicrowaveStepFive());
	}

	@Override
	public void pull(MicrowaveContext c) {
		c.setState(new MicrowaveStepThree());
	}	

	@Override
	public boolean canOpen() {
		return true;
	}

	@Override
	public boolean canClose() {
		return false;
	}

	@Override
	public boolean canPutFood() {
		return false;
	}

	@Override
	public boolean canGetFood() {
		return false;
	}

	@Override
	public boolean canHeating() {
		return true;
	}

}

MicrowaveStepOne.java

public class MicrowaveStepOne implements MicrowaveState {

	@Override
	public void push(MicrowaveContext c) {
		c.setState(new MicrowaveStepTwo());
	}

	@Override
	public void pull(MicrowaveContext c) {
		c.setState(new MicrowaveStepThree());
	}

	@Override
	public boolean canOpen() {
		return true;
	}

	@Override
	public boolean canClose() {
		return false;
	}

	@Override
	public boolean canPutFood() {
		return false;
	}
	
	@Override
	public boolean canGetFood() {
		return false;
	}

	@Override
	public boolean canHeating() {
		return false;
	}

}

MicrowaveStepThree.java

public class MicrowaveStepThree implements MicrowaveState {

	@Override
	public void push(MicrowaveContext c) {
		c.setState(new MicrowaveStepFour());
	}

	@Override
	public void pull(MicrowaveContext c) {
		c.setState(new MicrowaveStepTwo());
	}

	@Override
	public boolean canOpen() {
		return false;
	}

	@Override
	public boolean canClose() {
		return true;
	}

	@Override
	public boolean canPutFood() {
		return false;
	}
	
	@Override
	public boolean canGetFood() {
		return true;
	}

	@Override
	public boolean canHeating() {
		return false;
	}

}

MicrowaveStepTwo.java

public class MicrowaveStepTwo implements MicrowaveState {

	@Override
	public void push(MicrowaveContext c) {
		c.setState(new MicrowaveStepThree());
	}

	@Override
	public void pull(MicrowaveContext c) {
		c.setState(new MicrowaveStepOne());
	}

	@Override
	public boolean canOpen() {
		return false;
	}

	@Override
	public boolean canClose() {
		return true;
	}

	@Override
	public boolean canPutFood() {
		return true;
	}
	
	@Override
	public boolean canGetFood() {
		return false;
	}

	@Override
	public boolean canHeating() {
		return false;
	}

}

NormalHeating.java

public class NormalHeating implements Heating {

	@Override
	public void start(Food food) throws Exception {
		if (food == null)
			throw new Exception("Please put the food in a microwave oven.");
		
		if (food.isShell() || food.isSkin())
			throw new Exception("The food with a shell or skin.");
		
		System.out.println("Heating success.");
	}
}

NormalMicrowave.java

public class NormalMicrowave implements Microwave {
	MicrowaveContext context = null;
	Heating heating = null;
	Food food = null;

	public NormalMicrowave() {
		super();
		this.heating = new NormalHeating();
		this.context = new MicrowaveContext(new MicrowaveStepOne());
	}

	public NormalMicrowave(Heating heating) {
		super();
		this.heating = heating;
		this.context = new MicrowaveContext(new MicrowaveStepOne());
	}
	
	@Override
	public boolean open() {
		if (context.canOpen() && this.food != null) {
			context.pull();
			return true;
		} else if (context.canOpen() && this.food == null) {
			context.push();
			return true;
		}

		return false;
	}

	@Override
	public boolean putFood(Food food) {
		if (context.canPutFood()) {
			context.push();
			this.food = food;
			return true;
		}

		return false;
	}

	@Override
	public Food getFood() {
		if (context.canGetFood()) {
			context.pull();
			Food food = this.food;
			this.food = null;
			return food;
		}

		return null;
	}

	@Override
	public boolean close() {
		if (context.canClose() && this.food != null) {
			context.push();
			return true;
		} else if (context.canClose() && this.food == null) {
			context.pull();
			return true;
		}

		return false;
	}

	@Override
	public boolean startHeating() {
		try {
			if (context.canHeating()) {
				context.push();
				heating.start(this.food);
				context.push();
			}else{
				return false;
			}
		} catch (Exception e) {
			System.out.println(e.getMessage());
			return false;
		}

		return true;
	}
}