Stack Overflow?

[kyle_maddisson]

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.

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

[JosAH]

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

[pbrockway2]

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));
}

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.

[kyle_maddisson]

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?

[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

[JosAH]

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

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