calling method from extended Classes

[Masters1989]

I am basically using Java Constructor chaining, to try and add vehicles to my TrafficQueue. If I run the below code:



The part of code I am struggling to get working is

 
 
    public void add(RoadVehicle vehicle) {
        if (isFull()) {
            System.out.println("Queue is full! We cannot add any more vehicles to the Queue!");
            System.exit(1);
        } else {
 
 
            if (vehicle instanceof EmergencyVehicle && vehicle.isEmergency())  {
 
                addToFront(vehicle);
            } else {
                addToBack(vehicle);
            }
 
        }
    }
 

It wont allow me to run the method isEmergency() on vehicle.


FireEngine class:

public abstract class  EmergencyVehicle extends RoadVehicle {
 
 
    public boolean codeBlue = true;
 
 
 
    public EmergencyVehicle(String colour){
        super(colour);
    }
 
 
 
 
 
    public boolean isEmergency() {
        return codeBlue;
    }
 
    public void setEmergency(boolean newEmergency) {
        codeBlue = newEmergency;
    }
 
}
 

and EmergencyVehicle class:

public class FireEngine extends EmergencyVehicle {
 
 
    public FireEngine(String colour) {
        super (colour);
 
    }
    public FireEngine() {
        this("red");
 
    }
 
 
    public String toString () {
        if ("red".equals(colour)) {
 
            return "Fire Engine : CODEBLUE";
 
 
       }   else
            return colour + " FireEngine.";
    }
}
 

So, using extends, I am trying to add the vehicle to the front of the queue, if it isEmergency returns true.

The error I get is:
error, cannot find symbol.

I don't need the exact solution, but I think it should work as I have got the extends in each class. Can anyone point out where it goes wrong? I realise that the code needs neatening up slighty!

When adding a vehicle to the queue, I use

FireEngine car1 = new FireEngine("red");