Void problem

I need this for school and the book is not helping me. So I got this code and whenever I want to compile it says: incompatible types - found void but expected TEST

Code:

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class TEST
{
//Attribute
int positionX;
int positionY;
String ampelphase;
String farbe;
//Methoden
void positionSetzen(int xNeu, int yNeu)
{
    positionX = xNeu;
    positionY = yNeu;
    lampeOben.positionSetzen(positionX, positionY);
    lampeMitte.positionSetzen(positionX, positionY+1);
    lampeUnten.positionSetzen(positionX, positionY+2);
}
void farbeSetzen(String farbeNeu)
{
    farbeNeu = farbe;
    lampeOben.farbeSetzen(farbe);
    lampeMitte.farbeSetzen(farbe);
    lampeUnten.farbeSetzen(farbe);
}
void gruenSetzen()
{
    ampelphase = "gruen";
    lampeOben = farbeSetzen("schwarz");
    lampeMitte = farbeSetzen("schwarz");
    lampeUnten = farbeSetzen("gruen");
}
void gelbSetzen()
{
    ampelphase = "gelb";
    lampeOben = farbeSetzen("schwarz");
    lampeMitte = farbeSetzen("gelb");
    lampeUnten = farbeSetzen("schwarz");
}
void rotSetzen()
{
    ampelphase = "rot";
    lampeOben = farbeSetzen("rot");
    lampeMitte = farbeSetzen("schwarz");
    lampeUnten = farbeSetzen("schwarz");
}
void rotgelbSetzen()
{
    ampelphase = "rotgelb";
    lampeOben = farbeSetzen("rot");
    lampeMitte = farbeSetzen("gelb");
    lampeUnten = farbeSetzen("schwarz");
}
//Referenzattribute
TEST lampeOben;
TEST lampeMitte;
TEST lampeUnten;
//Konstruktor
TEST()
{
    positionX = 1;
    positionY = 1;
    ampelphase = "rot";
   
    lampeOben=new TEST();
    lampeMitte=new TEST();
    lampeUnten=new TEST();
    lampeOben=positionSetzen(1, 1);
    lampeMitte=positionSetzen(1, 2);
    lampeUnten=positionSetzen(1, 3);
    lampeOben=farbeSetzen("rot");
    lampeMitte=farbeSetzen("schwarz");
    lampeUnten=farbeSetzen("schwarz");
}

void Weiterschalten()
{
    if (ampelphase == "rot")
    {
            rotgelbSetzen();
        }
        else
        {
            if(ampelphase == "rotgelb")
            {
                gruenSetzen();
            }
            else
            {
                if (ampelphase == "gruen")
                {
                    gelbSetzen();
                }
                else
                {
                    rotSetzen();
                }
            }
        }
    }
       
}

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From this part:

Code:

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void gruenSetzen()
{
    ampelphase = "gruen";
    lampeOben = farbeSetzen("schwarz");
    lampeMitte = farbeSetzen("schwarz");
    lampeUnten = farbeSetzen("gruen");

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It shows the mistake at the end of:

Code:

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lampeOben = farbeSetzen("schwarz");

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the method farbeSetzen does not return a TEST object but void, so you cant assign void to lampeOben!
Change the method or/and think about the whole class. Why has a TEST object three references to TEST objects?
--> constructor:
lampeOben = new TEST();
lampeMitte = new TEST();
lampeUnten = new TEST();

this will end in a continuous loop (StackOverflow)!

Quote:

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Originally Posted by eRaaaa

the method farbeSetzen does not return a TEST object but void, so you cant assign void to lampeOben!
Change the method or/and think about the whole class. Why has a TEST object three references to TEST objects?
--> constructor:
lampeOben = new TEST();
lampeMitte = new TEST();
lampeUnten = new TEST();

this will end in a continuous loop (StackOverflow)!

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Thanks for the reply, but I really am a newbie to java and I do not exactly know how to fix it. So I have to remove the "void", but what should I add instead?

Quote:

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Originally Posted by Ricus

but what should I add instead?

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TEST ! But the whole class makes no sense. You have to think about it and try to learn the basics. Begin with simpler classes.
What's the aim of the class?

Well it was supposing to be a traffic light. I did everything the book said so far, doesn't work out somehow...

Call your class TrafficLight then.
TEST is not exactly a meaningful name if you know what the class is supposed to represent.

A TrafficLight has three states, Red/Amber/Green. You seem to have modelled this as three separate TrafficLights.
That's not really whata traffic light is is it? It is a single thing that displays one of three colours.

So try and think along those lines.