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Thread: Linked list inside a linked list
 04252010, 10:24 PM #1Member
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Linked list inside a linked list
Hello... I have a project where I'm supposed to create one linked list, where each node in that list (Graph Nodes) also contains a linked list (Adjacent Nodes). It's a simple singular linked list, and I've created the main one easily, but having issues thinking how to have each of it's nodes have their own linked list... I've created two separate Node classes, one for gNodes, and the other for aNodes. And in the gNode class, I have aNode objects like prev, curr, and head.
Here's my code for the two classes
Java Code:class gNode { private int element; //holds an int for graph list private gNode next; //reference to next graph node aNode head, prev, curr; //constructors node accepts a value and next node public gNode (int e, gNode n) { element = e; next = n; } //returns element public int getElement() { return element; } //returns next node public gNode getNext() { return next; } //sets the element public void setElement(int e) { element = e; } //sets the node public void setNext(gNode n) { next = n; } //insert an adjacent node into the gNode's list boolean adjInsert (int value, int value2) { if (adjExists(value)) { System.out.println (value + " already exists as an adjacency node to graph node " + value2 + ", did not insert " + value + "."); return false; } prev = null; curr = head; while (curr != null) { prev = curr; curr = curr.getNext(); } //makes a new node temp and sets value to it aNode temp = new aNode ('\0', null); temp.setElement(value); temp.setNext(curr); //if the list was empty if (prev == null) head = temp; //if list was not empty ... middle or end insert else prev.setNext(temp); System.out.println (value + " inserted as adjacent node to graph node " + value2 + "."); return true; } //Adjacent Node exist method public boolean adjExists (int value) { curr = head; //traverses through list, breaks out of loop if it sees value in it. //If it doesn't find, it will go all the way to the end, putting curr to null while ((curr != null) && (curr.getElement() != value)) curr = curr.getNext(); if (curr == null) return false; else return true; } //lists all adjacent nodes tied to this graph node public void listAllaNodes (int value) { // if (curr == null) // System.out.println("EMPTY"); // else // { System.out.print ("Listing all adjacent nodes to graph node " + value + ": "); for (aNode temp = head; temp != null; temp = temp.getNext()) { System.out.print(temp.getElement() + ", "); } System.out.println(); System.out.println(); //System.out.println("head is " + head); } // } } //end gNode class class aNode { private int element; //holds an int private aNode next; //reference to next node //constructors node accepts a value and next node public aNode (int e, aNode n) { element = e; next = n; } //returns element public int getElement() { return element; } //returns next node public aNode getNext() { return next; } //sets the element public void setElement(int e) { element = e; } //sets the node public void setNext(aNode n) { next = n; } } //end aNode class
Any help would be appreciated!
 04262010, 07:29 AM #2Member
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Anyone? I'm just having issues with all the nodes in gNode sharing the same linked list aNode.
This is what I have going on in the main
Java Code:graph g1 = new graph(); g1.insert(5); g1.insert(6); g1.insert(7); g1.ADJinsert(6, 5); g1.ADJinsert(7, 6); g1.listAllaNodesS(6);
Java Code:5 inserted as a graph node. 6 inserted as a graph node. 7 inserted as a graph node. 5 inserted as adjacent node to graph node 6. 6 inserted as adjacent node to graph node 7. Listing all adjacent nodes to graph node 6: 5, 6,
actually, now that I look at it, I said that all of the gNodes share the aNode list, which is wrong. 7's list is actually empty, so everything is going into one gNode right now.
Edit: Man, I should just wait and work on it more before I post haha. It seems to be working to what I want it to do now, had to mess with my ADJinstert method a little bit.
Here is the output now
Java Code:5 inserted as a graph node. 6 inserted as a graph node. 7 inserted as a graph node. 5 inserted as adjacent node to graph node 7. 6 inserted as adjacent node to graph node 6. Listing all adjacent nodes to graph node 7: 5, Listing all adjacent nodes to graph node 6: 6,
Last edited by viperlasson; 04262010 at 07:45 AM.
 07252010, 08:52 AM #3Member
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 07252010, 09:28 AM #4Member
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Do you need help with something in particular? This was a project I did a couple months ago while cramming for finals, the code is pretty messy and confusing. I DO have the code, but just giving people code isn't what this forum is about :)
 07262010, 02:21 PM #5Member
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Yes I understand, it fair enough, I have a similar problem and wanted to understand it better because I got stack when I used LinkedList so I want to know how you implimented your insert() method (ie g1.insert(5);), With my own I am struggling to use the size() method to get the number of degree of a particular vertex but going to your idea I think I can make it work but didnt understand how you use you insert vertex with you insert() method. If you don't mind I can go into your messy and confusing code and will work it out.
 07272010, 12:15 AM #6Member
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I'm a little confused of what you need, so I'll help you out the easy way. This is the code I came up with for my insert in the graph class.
Java Code://insert a new GNODE public boolean insert (int value) { if (exists(value)) { System.out.println (value + " already exists as a graph node, did not insert " + value + "."); return false; } prev = null; curr = head; while (curr != null) { prev = curr; curr = curr.getNext(); } //makes a new node temp and sets value to it gNode temp = new gNode ('\0', null); temp.setElement(value); temp.setNext(curr); //if the list was empty if (prev == null) head = temp; //if list was not empty ... middle or end insert else prev.setNext(temp); System.out.println (value + " inserted as a graph node."); return true; }
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