Tree and Arrays

Question

I had some trouble putting up a tree and run it to get a result as this picture below.

So I am supposed to create a tree with roots and children by a .txt file.

This is the code, and I will give a short explanation below.

public class Tree extends TreeFrame{

    Tree() throws FileNotFoundException {
        super();
    }

    private static final long serialVersionUID = 1L;    
    DefaultTreeModel model;
    Nod nod;
    static Tree main;
    static String filen ="";

    public void initTree() throws FileNotFoundException{

        filen = "C:/Users/MyComp/workspace/Lab5/src/Lab5/Life.txt";         
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(new File(filen));                              
        sc.nextLine();                                                          
        ArrayList<DefaultMutableTreeNode> ar = null;

        while (sc.hasNextLine()){
            String sc2 = sc.nextLine().replace("<", "");
            char chr = '/';

            if (sc2.charAt(0) != chr){
                String[] parts = sc2.split(" ");
                String[] parts2 = parts[1].split("=\"");
                String[] parts3 = sc2.split(">");
                nod = new Nod(parts2[1].substring(0, parts2[1].length() - 2), parts[0], parts3[1]);
                ar = new ArrayList<DefaultMutableTreeNode>();           

                for (int i = 0; i < nod.getDepth(); i++){
                    ar.add(nod);                                                
                }
            }

        buildTree(ar);                                                          
        }
    }

    void buildTree(ArrayList<DefaultMutableTreeNode> a){    

            model = new DefaultTreeModel (a);       
            tree = new JTree(model);                            
            tree.setBackground(Color.green);                    
    }


    void showDetails(TreePath path){
        if (path == null)
        return;

        int a = path.getPathCount()-1;
        DefaultMutableTreeNode b = (DefaultMutableTreeNode) path.getPathComponent(a);
        String info = ((Nod) b).getText();
        JOptionPane.showMessageDialog(this, info);
    }


    public static void main(String[] args) throws FileNotFoundException{
        if(args.length>0){
            filen=args[0];
        }

        main = new Tree();                                  
    }
}

Nod is just the class which makes the objects with name, level and text.

So the main thought was to, import the file -- > read it --> make objects of it --> create an array and add the "nodes"/objects in it --> make a TreeModel by the array/"nodes" --> create a tree by the TreeModel (as you see) --> and just run it with the extension to obtain the GUI. But I get syntax error on ArrayList<DefaultMutableTreeNode>.

Do you see the issue?

Always post the full error message with your question. You want to make the question as easy to answer as possible, no? — Hovercraft Full Of Eels
– Hovercraft Full Of Eels, Commented May 23, 2017 at 22:19
Note you're re-creating the arraylist with each iteration of a loop, something that doesn't make sense. Create the arraylist from the beginning and use it but don't keep re-creating one. — Hovercraft Full Of Eels
– Hovercraft Full Of Eels, Commented May 23, 2017 at 22:20
I just wanted to add all the objects in same array, but yea I think it is something wrong with that loop. — Alwe17
– Alwe17, Commented May 23, 2017 at 22:22
Again, you're recreating the ArrayList, meaning anything added to the ArrayList earlier in the loop will be thrown out when the new ArrayList replaces the old one. Again, does this make sense? — Hovercraft Full Of Eels
– Hovercraft Full Of Eels, Commented May 23, 2017 at 22:24
Also, why are you using ArrayList in the first place when you want to create a tree? An ArrayList is a linear list, not a tree structure. Why not create a JTree instead and a DefaultTreeModel? — Hovercraft Full Of Eels
– Hovercraft Full Of Eels, Commented May 23, 2017 at 22:25

Kevin Anderson · Accepted Answer · 2017-05-23 22:29:07Z

1

The immediate problem is that no DefaultTreeModel constructor accepts an ArrayList as an argument. See the docs here.

I think you might need to read this tutorial on how to use JTree.

answered May 23, 2017 at 22:29

Kevin Anderson

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Comments

A.Bau · Accepted Answer · 2017-05-23 22:29:51Z

0

You should change this if clause:

if (sc2.charAt(0) != chr){ String[] parts = sc2.split(" ");
String[] parts2 = parts[1].split("=\"");
String[] parts3 = sc2.split(">");
nod = new Nod(parts2[1].substring(0, parts2[1].length() - 2), parts[0], parts3[1]);
// ar = new ArrayList<DefaultMutableTreeNode>();
for (int i = 0; i < nod.getDepth(); i++){ ar.add(nod); } }

answered May 23, 2017 at 22:29

A.Bau

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