Stack Overflow?

I was wondering if somebody could help me with a problem I am having with my code. I am getting a stack overflow error, and it appears like something recursive is happening, but I don't see what is recursive with my code. I am trying to add an object to an arraylist in another class. I am trying to do it from the constructor of the object class I am constructing. Basically I am constructing the object, then trying to pass that object to an arraylist in another object. As far as I can tell the constructor should only be called once, so why it is acting recursive, I don't know. The particular object in question is an UrRobot, and I'm trying to store it in a World object's arraylist. Sure would appreciate some help with this one.

Here are the files listed in the order they are used. Keep in mind these are separate files/ classes. I don't know if that matters or not.

Code:

---

public class BasicUrRobotTest{
        public static void main(String args[]){

        UrRobot karel = new UrRobot(1,2,3,2);  //THE OBJECT I'M TRYING TO STORE IN WORLD'S ARRAYLIST


        karel.w.display();
        karel.display();
        karel.putBeeper();
        karel.putBeeper();
        karel.display();
        karel.w.display();
        }
}
----------------------------------------------------------------------------------------------------------------
import java.util.ArrayList;

public class UrRobot{
        /*********** declare variables for UrRobot class **************/

        static MyWorld w = new MyWorld();
        int street;
        int avenue;
        int direction;
        int beepers;
        String status=("on");
        public String compass[]={"not used","North", "South", "East", "West"};


                                /********* constructor ***********/
    public UrRobot(int street, int avenue, int direction, int beepers){
                this.street=street;
                this.avenue=avenue;
                this.direction=direction;
                this.beepers=beepers;
                this.status=status;
                w.robotList.add(new UrRobot(street, avenue, direction, beepers));  // STACK OVERFLOW
        }
/*****************************************************
                    Method definitons
******************************************************/

                /********** display() ********************/

        public void display(){ System.out.println("\n* UrRobot display() *\n");
                if(status.equals("on")){
                        System.out.println("Robot: ");
                        System.out.print("        Location: ");
                        System.out.print(street +" st, ");
                        System.out.println( avenue +" ave");
                        System.out.println("      Direction: " +compass[direction] );
                        System.out.println("  Beepers in bag: " +beepers);
                        System.out.println("          On/Off: " +status);
                }
                else{
                        System.out.println("**Error** display() message sent to robot that was turned off****\n");
                }
        }

                /****************** turnLeft ***************/

        public void turnLeft(){
                System.out.println("\n* UrRobot turnleft()*");
                turnLeft:
                if (status.equals("on")){
                        if(direction==1){
                                direction=4;
                                break turnLeft;
                        }
                        if (direction==2){
                                direction=3;
                                break turnLeft;
                        }
                        if (direction==3){
                                direction=1;
                                break turnLeft;
                        }
                        if (direction==4){
                                direction=2;
                                break turnLeft;
                        }
                }
                else
                        System.out.print("***Error*** turnleft() message sent to a robot that was turned off\n");
        }

                /*********** putBeeper ***************/

        public void putBeeper(){
                System.out.println("\n* UrRobot putBeeper() *");

                if(status.equals("on")){
                        if (beepers > 0){
                                beepers=beepers-1;
                                System.out.println("UrRobot beeper bag= "+beepers);
                                w.putBeeper(street, avenue);

                        }
                        else{
                                System.out.println("*** Error Shutoff *** putBeeper() message sent to robot that had no beepers in bag\n");
                                status="off";
                        }
                }
                else
                        System.out.print("**Error** putBeeper() message sent to a robot that was turned off\n");
        }


                /***************** pickBeeper ***********/

        public void pickBeeper(){
                System.out.println("\n* UrRobot pickBeeper()*");
                if(status.equals("on")){
                        if(w.foundBeepers(street, avenue)){
                                beepers=beepers+1;
                                System.out.println("UrRobot beeper bag= "+beepers);
                                w.pickBeeper(street, avenue);
                        }
                        else{
                                System.out.println("*** Error Shutoff *** pickBeeper() message sent to a robot with no beepers on that corner \n");
                                status = "off";
                        }
                }
                else
                        System.out.print("**Error** pickBeeper() message sent to a robot that was turned off\n");
        }

                /****************** move() **************/

        public void move(){
                System.out.println("\n* UrRobot move()*");
                if(status.equals("on")){
                    if(!w.hitWall(street, avenue, direction)){
                            if (direction==1)
                                        street=street+1;
                                if (direction==2 && street<2){
                                        System.out.println("*** Error Shutoff *** robot ran into a wall \n");
                                        status="off";
                                }
                                else{
                                        if(direction==2)
                                        street=street-1;
                                }
                                if (direction==3)
                                        avenue=avenue+1;
                                if (direction==4 && avenue<2){
                                        System.out.println("*** Error Shutoff *** robot ran into a wall \n");
                                        status="off";
                                }
                                else if(direction==4)
                                        avenue=avenue-1;
                    }
                    else{
                            System.out.println("*** Error Shutoff *** robot ran into a wall");
                            status="off";
                    }
                }
                else
                        System.out.print("*** Error Shutoff *** move() message sent to a robot that was turned off\n");
        }

                /***************** turnOff ***************/

        public void turnOff(){
                System.out.println("* UrRobotturnoff() *");
                if(status.equals("on")){
                        status=("off");
                }
                else
                        System.out.print("** Error ** turnOff() message sent to a robot that was turned off\n");
        }

        public String toString()
                {
                return "St: " +street +", " +"Ave: " + avenue +", "+"Dir: "+compass[direction] +", " +"Bag: "+beepers +", "+status;
        }
    static public void displayWorld()
        {
                w.display();
        }
}
------------------------------------------------------------------------------------------------------------------------------------

import java.util.ArrayList;

public class MyWorld{

/************** declare variables ****************/
        ArrayList<Beepers> beeperList = new ArrayList<Beepers>();
        ArrayList<UrRobot> robotList = new ArrayList<UrRobot>();
        Walls[] wallsNorth = new Walls[1];
        Walls[] wallsSouth = new Walls[1];
        Walls[] wallsEast = new Walls[1];
        Walls[] wallsWest = new Walls[1];
        boolean found=false;

/*********** Constructor ************/
public MyWorld(){ /* add walls and beepers here */
        System.out.println("*** MyWorld Constructor ***\n");
        // beeperList.add(new Beepers (10,101,100));
        // beeperList.add(new Beepers (1,2,0));

        wallsNorth[0]=new Walls(1,2);
        wallsSouth[0]=new Walls(1,2);
        wallsEast[0]=new Walls(1,2);
        wallsWest[0]=new Walls(1,2);


}


        /******* World methods ************/

        // searches ArrayList for beeperpile on robots current corner
        public boolean foundBeepers(int UrRobotStreet, int UrRobotAvenue){
        //        System.out.println("* w.foundBeepers *");
                for(Beepers e : beeperList){
                        System.out.println("("+e.getStreet()+","+e.getAvenue()+")");
                        if (e.getStreet()==UrRobotStreet && e.getAvenue()==UrRobotAvenue && e.getCount()>0){
                                found = true;
                                System.out.println("* match found *");
                        }
                        else{
                                found = false;
                        }
                }
                return found;
        }

                // decrements beeper-pile count
        public void pickBeeper(int UrRobotStreet, int UrRobotAvenue){ //System.out.println("* w.pickBeeper() *");
                if(foundBeepers(UrRobotStreet, UrRobotAvenue)){
                        for(Beepers e : beeperList){
                                if (e.getStreet()==UrRobotStreet && e.getAvenue()==UrRobotAvenue && e.getCount()>0)
                                        e.decrementCount();
                                }
                        }
                return ;
                }

        // increments beeper-pile count
        public void putBeeper(int UrRobotStreet, int UrRobotAvenue){ //System.out.println("* w.putBeeper() *");
                if(foundBeepers(UrRobotStreet, UrRobotAvenue)){
                                for(Beepers e : beeperList){
                                        if (e.getStreet()==UrRobotStreet && e.getAvenue()==UrRobotAvenue)
                                                e.incrementCount();
                                }
                }
                if(!foundBeepers(UrRobotStreet, UrRobotAvenue)){
                        beeperList.add(new Beepers (UrRobotStreet, UrRobotAvenue, 1));

                }
                return ;
        }

        // displays all World object information
        public void display(){
                        for(Beepers e : beeperList){
                          System.out.println( "Beeper street: " + e.getStreet() +
                                              " " +  "avenue: " + e.getAvenue() +
                                              " " +  "count: " + e.getCount());
            }
                        for(Walls e : wallsNorth){
                System.out.println( "Wall street: " + e.getStreet() +
                                              " " +  "avenue: " + e.getAvenue());
            }
            for(Walls e : wallsSouth){
                System.out.println( "Wall street: " + e.getStreet() +
                                    " " +  "avenue: " + e.getAvenue());
            }
            for(Walls e : wallsEast){
                System.out.println( "Wall street: " + e.getStreet() +
                                  " " +  "avenue: " + e.getAvenue());
            }
            for(Walls e : wallsWest){
                System.out.println( "Wall street: " + e.getStreet() +
                                    " " +  "avenue: " + e.getAvenue());
            }
        }

        // checks to see if robot hit wall
        public boolean hitWall(int UrRobotStreet, int UrRobotAvenue, int UrRobotDirection){

                boolean collision = false;

                //System.out.println("World checking for wall collisions");

                if (UrRobotDirection==1){
                        for(Walls e : wallsNorth){
                                if(e.getStreet()==UrRobotStreet && e.getAvenue()==UrRobotAvenue){
                                        collision=true;
                                }
                        }
                }
                if (UrRobotDirection==2){
                        for(Walls e : wallsSouth){
                                if(e.getStreet()==UrRobotStreet && e.getAvenue()==UrRobotAvenue){
                                        collision=true;
                                }
                        }
                }
                if (UrRobotDirection==3){
                        for(Walls e : wallsEast){
                                if(e.getStreet()==UrRobotStreet && e.getAvenue()==UrRobotAvenue){
                                        collision=true;
                                }
                        }
                }
                if (UrRobotDirection==4){
                        for(Walls e : wallsWest){
                                if(e.getStreet()==UrRobotStreet && e.getAvenue()==UrRobotAvenue){
                                        collision=true;
                                }
                        }
                }
                return collision;
        }
}

---

SORRY ABOUT THE INDENTATION, IT DOESN'T WANT TO KEEP MY SPACING WHEN I POST

Please, this is just too much code to plough through; try to come up with a small(er) example that shows the behaviour you described (and preferably make it compilable so we can test it).

kind regards,

Jos

Code:

---

public UrRobot(int street, int avenue, int direction, int beepers){
    this.street=street;
    this.avenue=avenue;
    this.direction=direction;
    this.beepers=beepers;
    this.status=status;
    w.robotList.add(new UrRobot(street, avenue, direction, beepers));
}

---

Quote:

---

Basically I am constructing the object, then trying to pass that object to an arraylist

---

But you aren't doing that: you are passing a new object to the list. Importantly, you are constructing a new object within the constructor which is what causes the stack overflow.

What? I thought it is constructed in BasicUrRobotTest. I thought UrRobot karel=new UrRobot(1,2,0) is what constructed it. I just want to send the paramaters to the arrayList in World? My reasoning being that the UrRobot constructor received the paramaters to construct the object. Then I just wanted to send that robot to the arrayList. Where else would I do that?

I'm sorry I cannot seem to shorten this anymore than it already is. If I do I just get errors. Each file works together and if omit anything, it can't find...., enumerator expected, etc. I tried to explain what lines I am having trouble with. If you look at the comments, it says where the problem is and what the error is I am getting on that line. As you can probably tell, I am not a very good programmer yet, but I feel I could be with practice and some help understanding what is going on. Perhaps I could just attach the files, would that make things easier? Oh never mind, who would have thought that a .java file would be an invalid file on a Java forum :(doh):

Quote:

---

Originally Posted by kyle_maddisson

I'm sorry I cannot seem to shorten this anymore than it already is. If I do I just get errors. Each file works together and if omit anything, it can't find...., enumerator expected, etc. I tried to explain what lines I am having trouble with. If you look at the comments, it says where the problem is and what the error is I am getting on that line. As you can probably tell, I am not a very good programmer yet, but I feel I could be with practice and some help understanding what is going on. Perhaps I could just attach the files, would that make things easier? Oh never mind, who would have thought that a .java file would be an invalid file on a Java forum :(doh):

---

Pbrockway2 already told you were the error is: in the constructor of your robot class, you're trying to construct another robot and add that one to a list; but the other robot also tries to construct another robot in its constructor (it's the same constructor code, called recursively) and add another new one to the list, ad infinitum; that's why the stack overflows.

kind regards,

Jos