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Path of TreeSelectionEvent

Jeff Grant
Ranch Hand

Joined: Dec 19, 2001
Posts: 169
I have a linked list which populates a JTree exactly as it's made. Here is the declaration of my List class.

All of that works fine, my JTree is populated appropriately after my list is built.

When my JTree has a line selected, it expands the tree accordingly. I have a JLabel at the bottom of my application which gets populated by saying what line is selected ("Selected Line: #"). This line number is of the parent node of the tree (first child of the root node), not any sub children of those parent nodes.

To find this line number, I parse through the linked list comparing the first string within the TreeSelectionEvent.getPath() with my current work variable as it goes through the parent root children.

Here is the code to my list crawler.

My problem is that it is possible for the JTree to have nodes with the same data. This is correct. However, when I step through the linked list, I find the first matching object and it stops.. not necessarily at the selected item but at the first one where the value is equal.

So my question is this.. is there another method to tell where the cursor at using another method than my list crawler matching List.value
[ March 22, 2005: Message edited by: Jeff Grant ]
Leonardo Pjetri
Greenhorn

Joined: Dec 21, 2004
Posts: 29
If u gone have a list or tree populated with the same type of data & want to uniquely identify them, give em a unique value.
E.g.: current = newLink( uniqueNumber,dataValue);
Jeff Grant
Ranch Hand

Joined: Dec 19, 2001
Posts: 169
Originally posted by pete duncan:
If u gone have a list or tree populated with the same type of data & want to uniquely identify them, give em a unique value.
E.g.: current = newLink( uniqueNumber,dataValue);

You're saying to modify my List class to have the unique key in the class?

This would still not solve my issue as I cannot tell which item in the JTree was selected (doesn't have a unique index I can seem to find).
Leonardo Pjetri
Greenhorn

Joined: Dec 21, 2004
Posts: 29
Modify the tree too dude.
Jeff Grant
Ranch Hand

Joined: Dec 19, 2001
Posts: 169
Originally posted by pete duncan:
Modify the tree too dude.

Couldn't really understand your first reply.. which is why I had to question it.

I do not have an option to simply put a unique key in the JTree display.

How about an example constructor of whatever you are suggesting as far as the tree is concerned... be it JTree or DefaultMutableTreeNode
Leonardo Pjetri
Greenhorn

Joined: Dec 21, 2004
Posts: 29
// tree.java
// demonstrates binary tree
// to run this program: C>java TreeApp
import java.io.*;
import java.util.*; // for Stack class
////////////////////////////////////////////////////////////////
class Node
{
public int iData; // data item (key)
public double dData; // data item
public Node leftChild; // this node's left child
public Node rightChild; // this node's right child

public void displayNode() // display ourself
{
System.out.print('{');
System.out.print(iData);
System.out.print(", ");
System.out.print(dData);
System.out.print("} ");
}
} // end class Node
////////////////////////////////////////////////////////////////
class Tree
{
private Node root; // first node of tree

// -------------------------------------------------------------
public Tree() // constructor
{ root = null; } // no nodes in tree yet
// -------------------------------------------------------------
public Node find(int key) // find node with given key
{ // (assumes non-empty tree)
Node current = root; // start at root
while(current.iData != key) // while no match,
{
if(key < current.iData) // go left?
current = current.leftChild;
else // or go right?
current = current.rightChild;
if(current == null) // if no child,
return null; // didn't find it
}
return current; // found it
} // end find()
// -------------------------------------------------------------
public void insert(int id, double dd)
{
Node newNode = new Node(); // make new node
newNode.iData = id; // insert data
newNode.dData = dd;
if(root==null) // no node in root
root = newNode;
else // root occupied
{
Node current = root; // start at root
Node parent;
while(true) // (exits internally)
{
parent = current;
if(id < current.iData) // go left?
{
current = current.leftChild;
if(current == null) // if end of the line,
{ // insert on left
parent.leftChild = newNode;
return;
}
} // end if go left
else // or go right?
{
current = current.rightChild;
if(current == null) // if end of the line
{ // insert on right
parent.rightChild = newNode;
return;
}
} // end else go right
} // end while
} // end else not root
} // end insert()
// -------------------------------------------------------------
public boolean delete(int key) // delete node with given key
{ // (assumes non-empty list)
Node current = root;
Node parent = root;
boolean isLeftChild = true;

while(current.iData != key) // search for node
{
parent = current;
if(key < current.iData) // go left?
{
isLeftChild = true;
current = current.leftChild;
}
else // or go right?
{
isLeftChild = false;
current = current.rightChild;
}
if(current == null) // end of the line,
return false; // didn't find it
} // end while
// found node to delete

// if no children, simply delete it
if(current.leftChild==null &&
current.rightChild==null)
{
if(current == root) // if root,
root = null; // tree is empty
else if(isLeftChild)
parent.leftChild = null; // disconnect
else // from parent
parent.rightChild = null;
}

// if no right child, replace with left subtree
else if(current.rightChild==null)
if(current == root)
root = current.leftChild;
else if(isLeftChild)
parent.leftChild = current.leftChild;
else
parent.rightChild = current.leftChild;

// if no left child, replace with right subtree
else if(current.leftChild==null)
if(current == root)
root = current.rightChild;
else if(isLeftChild)
parent.leftChild = current.rightChild;
else
parent.rightChild = current.rightChild;

else // two children, so replace with inorder successor
{
// get successor of node to delete (current)
Node successor = getSuccessor(current);

// connect parent of current to successor instead
if(current == root)
root = successor;
else if(isLeftChild)
parent.leftChild = successor;
else
parent.rightChild = successor;

// connect successor to current's left child
successor.leftChild = current.leftChild;
} // end else two children
// (successor cannot have a left child)
return true; // success
} // end delete()
// -------------------------------------------------------------
// returns node with next-highest value after delNode
// goes to right child, then right child's left descendents
private Node getSuccessor(Node delNode)
{
Node successorParent = delNode;
Node successor = delNode;
Node current = delNode.rightChild; // go to right child
while(current != null) // until no more
{ // left children,
successorParent = successor;
successor = current;
current = current.leftChild; // go to left child
}
// if successor not
if(successor != delNode.rightChild) // right child,
{ // make connections
successorParent.leftChild = successor.rightChild;
successor.rightChild = delNode.rightChild;
}
return successor;
}
// -------------------------------------------------------------
public void traverse(int traverseType)
{
switch(traverseType)
{
case 1: System.out.print("\nPreorder traversal: ");
preOrder(root);
break;
case 2: System.out.print("\nInorder traversal: ");
inOrder(root);
break;
case 3: System.out.print("\nPostorder traversal: ");
postOrder(root);
break;
}
System.out.println();
}
// -------------------------------------------------------------
private void preOrder(Node localRoot)
{
if(localRoot != null)
{
System.out.print(localRoot.iData + " ");
preOrder(localRoot.leftChild);
preOrder(localRoot.rightChild);
}
}
// -------------------------------------------------------------
private void inOrder(Node localRoot)
{
if(localRoot != null)
{
inOrder(localRoot.leftChild);
System.out.print(localRoot.iData + " ");
inOrder(localRoot.rightChild);
}
}
// -------------------------------------------------------------
private void postOrder(Node localRoot)
{
if(localRoot != null)
{
postOrder(localRoot.leftChild);
postOrder(localRoot.rightChild);
System.out.print(localRoot.iData + " ");
}
}
// -------------------------------------------------------------
public void displayTree()
{
Stack globalStack = new Stack();
globalStack.push(root);
int nBlanks = 32;
boolean isRowEmpty = false;
System.out.println(
"......................................................");
while(isRowEmpty==false)
{
Stack localStack = new Stack();
isRowEmpty = true;

for(int j=0; j<nBlanks; j++)
System.out.print(' ');

while(globalStack.isEmpty()==false)
{
Node temp = (Node)globalStack.pop();
if(temp != null)
{
System.out.print(temp.iData);
localStack.push(temp.leftChild);
localStack.push(temp.rightChild);

if(temp.leftChild != null ||
temp.rightChild != null)
isRowEmpty = false;
}
else
{
System.out.print("--");
localStack.push(null);
localStack.push(null);
}
for(int j=0; j<nBlanks*2-2; j++)
System.out.print(' ');
} // end while globalStack not empty
System.out.println();
nBlanks /= 2;
while(localStack.isEmpty()==false)
globalStack.push( localStack.pop() );
} // end while isRowEmpty is false
System.out.println(
"......................................................");
} // end displayTree()
// -------------------------------------------------------------
} // end class Tree
////////////////////////////////////////////////////////////////
class TreeApp
{
public static void main(String[] args) throws IOException
{
int value;
Tree theTree = new Tree();

theTree.insert(50, 1.5);
theTree.insert(25, 1.2);
theTree.insert(75, 1.7);
theTree.insert(12, 1.5);
theTree.insert(37, 1.2);
theTree.insert(43, 1.7);
theTree.insert(30, 1.5);
theTree.insert(33, 1.2);
theTree.insert(87, 1.7);
theTree.insert(93, 1.5);
theTree.insert(97, 1.5);

while(true)
{
System.out.print("Enter first letter of show, ");
System.out.print("insert, find, delete, or traverse: ");
int choice = getChar();
switch(choice)
{
case 's':
theTree.displayTree();
break;
case 'i':
System.out.print("Enter value to insert: ");
value = getInt();
theTree.insert(value, value + 0.9);
break;
case 'f':
System.out.print("Enter value to find: ");
value = getInt();
Node found = theTree.find(value);
if(found != null)
{
System.out.print("Found: ");
found.displayNode();
System.out.print("\n");
}
else
System.out.print("Could not find ");
System.out.print(value + '\n');
break;
case 'd':
System.out.print("Enter value to delete: ");
value = getInt();
boolean didDelete = theTree.delete(value);
if(didDelete)
System.out.print("Deleted " + value + '\n');
else
System.out.print("Could not delete ");
System.out.print(value + '\n');
break;
case 't':
System.out.print("Enter type 1, 2 or 3: ");
value = getInt();
theTree.traverse(value);
break;
default:
System.out.print("Invalid entry\n");
} // end switch
} // end while
} // end main()
// -------------------------------------------------------------
public static String getString() throws IOException
{
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(isr);
String s = br.readLine();
return s;
}
// -------------------------------------------------------------
public static char getChar() throws IOException
{
String s = getString();
return s.charAt(0);
}
//-------------------------------------------------------------
public static int getInt() throws IOException
{
String s = getString();
return Integer.parseInt(s);
}
// -------------------------------------------------------------
} // end class TreeApp
////////////////////////////////////////////////////////////////


It�s a runeble program, its similar to a linked list we have iData to uniquely identify the node,the dData to hold our value & left and right links.

http://www.samspublishing.com/title/0672324539#
go here and download the sourse code & applet example. I recommend the book too.
Jeff Grant
Ranch Hand

Joined: Dec 19, 2001
Posts: 169
I did not want to reinvent a tree class and node class.. so I ended up stepping through my linked list based on where the tree was expanded and the current selected row number.

Thanks for the help though.
 
Don't get me started about those stupid light bulbs.
 
subject: Path of TreeSelectionEvent
 
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