重构18-Replace exception with conditional（条件替代异常）

public class Microwave {
    private MicrowaveMotor Motor;//getter setter

public Boolean start(Object food) {
        Boolean foodCooked = false;
        try {
            Motor.Cook(food);
foodCooked = true;
} catch (InUseException e) {
            foodcooked = false;
}
        return foodCooked;
}
}

public class Microwave {
    private MicrowaveMotor Motor;//getter setter
public Boolean start(Object food) {
        if (Motor.IsInUse) return false;
Motor.Cook(food);
        return true;
}
}