Solved

Storing point coordinates in a Stack

Posted on 2011-09-14
10
496 Views
Last Modified: 2012-05-12
Hi Experts,

I am trying to store some coordinates (from a grid) into a Stack data structure.
I have two classes: MyStack.java and MyPoints.java, the latter extends Point
public class MyStack
{
     static void showPush(Stack stack, Mypoint pt)
      {
            stack.push(pt);
            
            System.out.println("push(" + pt + ")");
            System.out.println("stack: " + stack);
      }
      static void showPop(Stack st)
      {
            System.out.print("pop -> ");
            
            Mypoint pt = (Mypoint) st.pop();

            System.out.println(pt);
            System.out.println("stack: " + st);
      }
}

From main, I am having the following implementation:
public static void main(String args[])
      {
            Stack st = new Stack();
            Mypoint point = new Mypoint(3,1);
            Mypoint point2 = new Mypoint(3,2);
            Mypoint point3 = new Mypoint(5,1);
            
            System.out.println("stack: " + st);

            showPush(st, point);
            showPush(st, point2);
            showPush(st, point3);
            showPop(st);
            showPop(st);
            showPop(st);
            
            try {
            showPop(st);
            } catch (EmptyStackException e) {
            System.out.println("empty stack");
            }
      }

I am getting weird output rather... Could you please guide me achieve this. Thanks.

OUTPUT:
stack: []
push(org.me.stack.Mypoint[x=0,y=0])
stack: [org.me.stack.Mypoint[x=0,y=0]]
push(org.me.stack.Mypoint[x=0,y=0])
stack: [org.me.stack.Mypoint[x=0,y=0], org.me.stack.Mypoint[x=0,y=0]]
push(org.me.stack.Mypoint[x=0,y=0])
stack: [org.me.stack.Mypoint[x=0,y=0], org.me.stack.Mypoint[x=0,y=0], org.me.stack.Mypoint[x=0,y=0]]
pop -> org.me.stack.Mypoint[x=0,y=0]
stack: [org.me.stack.Mypoint[x=0,y=0], org.me.stack.Mypoint[x=0,y=0]]
pop -> org.me.stack.Mypoint[x=0,y=0]
stack: [org.me.stack.Mypoint[x=0,y=0]]
pop -> org.me.stack.Mypoint[x=0,y=0]
stack: []
org.me.stack.Mypoint[x=0,y=0]
pop -> empty stack
0
Comment
Question by:Smanyx
10 Comments
 
LVL 40

Expert Comment

by:gurvinder372
ID: 36535215
can you share the Stack class as well?
0
 

Author Comment

by:Smanyx
ID: 36535493
Sorry for the delay...
I have supplied the MyStack class, may be you mean MyPoint class ??
It's just a simple class

import java.awt.*;
public class MyPoint extends Point
{
     private int X;
     private int Y;
     //constructor
      public Point (int a, int b)
      {

      }

}
0
 
LVL 86

Accepted Solution

by:
CEHJ earned 300 total points
ID: 36535537
You're not setting the instance variables to the value of the parameters
0
 

Assisted Solution

by:Smanyx
Smanyx earned 0 total points
ID: 36535832
I think I was getting confused myself a bit.
I realized I didn't need to have MyPoint class at all.
So, I solved my problem by getting rid of MyPoint class and  just by having only ONE class MyStack.java and importing java.awt.*;
 package org.me.stack;

import java.util.*;
import java.awt.*;
public class Mystack 
{
	
	@SuppressWarnings({ "rawtypes", "unchecked" }) 
	static void showPush(Stack stack, Point pt)
	{
		stack.push(pt);
		
		System.out.println("push(" + pt + ")");
		System.out.println("stack: " + stack);
	}
	@SuppressWarnings("rawtypes")
	static void showPop(Stack st) 
	{
		System.out.print("pop -> ");
		
		Point pt = (Point) st.pop();
		System.out.println(pt);
		System.out.println("stack: " + st);
	}
	
		
}

Open in new window


And implementing that in main :
package org.me.stack;

import java.util.EmptyStackException;
import java.awt.*;
import java.util.Stack;

public class Main extends Mystack {

	/**
	 * @param args
	 */
	@SuppressWarnings("rawtypes")
	public static void main(String args[]) 
	{
		Stack st = new Stack();
		Point pts = new Point(6,1);
		Point pts2 = new Point(5,1);
		Point pts3 = new Point(5,2);
		Point pts4 = new Point(5,3);
		Point pts5 = new Point(6,2);
				
		System.out.println("stack: " + st);

		showPush(st, pts);
		showPush(st, pts2);
		showPush(st, pts3);
		showPush(st, pts4);
		showPush(st, pts5);
		showPop(st);
		showPop(st);
		showPop(st);
		showPop(st);
		showPop(st);
		
		try {
		showPop(st);
		} catch (EmptyStackException e) {
		System.out.println("empty stack");
		}
	}

}

Open in new window


OUTPUT:
stack: []
push(java.awt.Point[x=6,y=1])
stack: [java.awt.Point[x=6,y=1]]
push(java.awt.Point[x=5,y=1])
stack: [java.awt.Point[x=6,y=1], java.awt.Point[x=5,y=1]]
push(java.awt.Point[x=5,y=2])
stack: [java.awt.Point[x=6,y=1], java.awt.Point[x=5,y=1], java.awt.Point[x=5,y=2]]
push(java.awt.Point[x=5,y=3])
stack: [java.awt.Point[x=6,y=1], java.awt.Point[x=5,y=1], java.awt.Point[x=5,y=2], java.awt.Point[x=5,y=3]]
push(java.awt.Point[x=6,y=2])
stack: [java.awt.Point[x=6,y=1], java.awt.Point[x=5,y=1], java.awt.Point[x=5,y=2], java.awt.Point[x=5,y=3], java.awt.Point[x=6,y=2]]
pop -> java.awt.Point[x=6,y=2]
stack: [java.awt.Point[x=6,y=1], java.awt.Point[x=5,y=1], java.awt.Point[x=5,y=2], java.awt.Point[x=5,y=3]]
pop -> java.awt.Point[x=5,y=3]
stack: [java.awt.Point[x=6,y=1], java.awt.Point[x=5,y=1], java.awt.Point[x=5,y=2]]
pop -> java.awt.Point[x=5,y=2]
stack: [java.awt.Point[x=6,y=1], java.awt.Point[x=5,y=1]]
pop -> java.awt.Point[x=5,y=1]
stack: [java.awt.Point[x=6,y=1]]
pop -> java.awt.Point[x=6,y=1]
stack: []
pop -> empty stack
0
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LVL 86

Expert Comment

by:CEHJ
ID: 36535851
Yes, now the parameters ARE getting set to the Point class since your broken constructor for the subclass is no longer being used. I assumed you were going to do other things with your subclass or you shouldn't have made one in the first place
0
 
LVL 10

Expert Comment

by:gordon_vt02
ID: 36542837
On a side note, it's always better to explicitly import only the classes you need instead of doing a .* import.  That way you avoid unintentional naming conflicts.
0
 

Author Comment

by:Smanyx
ID: 36567589
I've requested that this question be closed as follows:

Accepted answer: 0 points for Smanyx's comment http:/Q_27307186.html#36535832

for the following reason:

Thanks for your help anyway. I do appreciate it.<br />Cheers.
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 36567590
I gave the reason for the problem before the OP decided to close it
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 36592326
:)
0

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