Java: Tree Creation

Question

Given the alphabet and a morse code value for each letter...

a._
b_...
c_._.
d_..  //file to be read in
e.
f.._.

I'm attempting to create a tree, finding the position for a letter in the tree by scanning the code, and branching left for a dot and branching right for a dash.

I've created a node class with the typical numberNode left and numberNode right variables along with morseCode and letter . Here's my function.

aList is an arraylist of created nodes read in from a file. rootNode is the root of the tree, having no set letter or morsecode .

    public static void createTree(ArrayList<numberNode> aList, numberNode rootNode)
{
    for (numberNode n : aList)  //for each numberNode in aList
    {
        int lengthOfCode = n.getmorseCode().length()-1;  //get the length of the morsecode
        numberNode currentNode = rootNode; //sets currentNode to the rootNode at first
        for (int i=0; i<lengthOfCode; i++) 
        {
            char c = n.getmorseCode().charAt(i); //for each char in morsecode until it gets to the end
            if (c == '.')
            {
                if (currentNode.getleft() = null) //if currentnode left is null
                {
                    numberNode newLeftNode = new numberNode(); //create new node
                    currentNode.setleft(newLeftNode); //set current node left to the new node
                    if (i == lengthOfCode)
                    {
                        currentNode.setleft(n); //if end of morse code, set the current node left's to n
                    }
                    else
                    {
                        currentNode = newLeftNode; //else change current node to the newly created leftnode
                    }

                }
                else //if current node left is not null
                {
                    if (i == lengthOfCode)
                    {
                        currentNode.setleft(n); //if at end of morse code
                    }
                    currentNode = currentNode.getleft(); //if not at end set current node to current node's left

                }

            }
            if (c == '_')
            {
                if (currentNode.right() =null)
                {
                    numberNode newRightNode = new numberNode();
                    currentNode.setleft(newRightNode);
                    if (i == lengthOfCode)
                    {
                        currentNode.setright(n);
                    }
                    else
                    {
                        currentNode = newRightNode;
                    }

                }
                else
                {
                    if (i == lengthOfCode)
                    {
                        currentNode.setright(n);
                    }
                    currentNode = currentNode.getright();

                }

            }
        }
    }
}

Couple questions I have...

Is my algorithm at least correct?

Is there an alternate way of doing this without it being so ugly?

If you need to see any more of my code please don't hesitate to ask. Thanks for your time, I truly appreciate it!

EDIT: Currently runs, but when I try to print out the output using...

       for (numberNode n : nodeArray)
    {
        System.out.println(n.getletter());
        System.out.println(n.getleft().getletter().toString()); //error here
        System.out.println(n.getright().getletter());
        System.out.println("");
    }

I get an error where indicated,Any ideas on what's going wrong?

Answer 1

First, when you try to print the values out, what did the compiler say was the error on System.out.println(n.getleft().getletter().toString()); //error here?

Is each letter suppose to be the root of it's own tree? If it is suppose to be on tree, I would have a reference pointer at the start that would contain references to every letter in the alphabet, while the nodes branching off each letter would have the particular sequence that represents the Morse code for that letter. But if I was free to do whatever, I would simply create an array of 26 characters that contain a MorseCode object that has two fields, one containing the Letter and the other containing the Morse Code that is associated with that letter.

It would be helpful to understand what the output is suppose to be for this program and clarify what is in the file you are reading into the arrayList. What does that data look like?