Populate JTree from String array Structured as Paths

Question

I need help in my Java project. How do I populate my JTree dynamically from arrays of String patterned as paths?. Like, String

paths[][]={{"Animals", "Birds","Non_flying" ,"Chicken"},
{"Animals","Birds","Non_flying","Ostrich"}, 
{"Animals","Birds","Flying","Eagle"},
{"Animals","Birds","Flying","Crow"},
{"Animals","Reptiles","Lizard"},
{"Plants"," Fruit Bearing","Fruits","Mango"},
{"Plants"," Fruit Bearing","Vegetable","Eggplant"},
{"Plants"," Non-fruit Bearing","Sunflower"}};

Like this I tried the code below but it does not merge similar nodes. It must be the conditions inside the treeify() method:

import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;

public class TreeTest extends javax.swing.JFrame{
    static JTree tree; 
    public static void setTree(){
        String paths[][]={{"Animals", "Birds","Non_flying" ,"Chicken"},
                         {"Animals","Birds","Non_flying","Ostrich"},    
                         {"Animals","Birds","Flying","Eagle"},
                         {"Animals","Birds","Flying","Crow"},
                         {"Animals","Reptiles","Lizard"},
                         {"Plants"," Fruit Bearing","Fruits","Mango"},
                         {"Plants"," Fruit Bearing","Vegetable","Eggplant"}, 
                         {"Plants"," Non-fruit Bearing","Sunflower"}};
        tree = new JTree(treeify(paths)); 
    }

    public static <T> DefaultMutableTreeNode treeify(String[][] paths) {
        DefaultMutableTreeNode root = null;
        DefaultMutableTreeNode subRoot = null;
        for ( String[] parent : paths)
        for ( String value : parent){
            if (root == null) {
                root = new DefaultMutableTreeNode(value);
            } else if (subRoot == null){
                subRoot = new DefaultMutableTreeNode(value);
                root.add(subRoot);
            } else {
                DefaultMutableTreeNode child = new DefaultMutableTreeNode(value);
                subRoot.add(child);
                subRoot = child;
            }
        }
        return root; 
    }

    public static void main(String[] args) {
        TreeTest test = new TreeTest();
        setTree();
        test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        test.add(new JScrollPane(tree));
        test.setSize(500,400);
        test.setLocationRelativeTo(null);
        test.setVisible(true); 
    }
}

You've got to search the model you're building in order to know where a new node fits in. Say you're trying to add {"Animals", "Birds","Non_flying" ,"Chicken"}. Start with the root as your "current" node and look for a child node called "Animals"; if you don't find it, add an empty "Animals" node as a child of "current". Now make that found or added "Animals" node your new "current" node, and look through its children for a "Birds" node, adding it if necessary, and so on... — Kevin Anderson
– Kevin Anderson, Commented Mar 18, 2020 at 10:58
Anyone who could give me code here. I'm new to JTree. Spent 2 weeks solving the problem and nothing works. — edpanferry
– edpanferry, Commented Mar 18, 2020 at 14:31

Kevin Anderson · Accepted Answer · 2020-03-19 06:34:01Z

Here's a version of treeify() that implements the strategy I was outlining in my comment. It's not the most elegant thing ever, but it gets the job done:

public static DefaultMutableTreeNode treeify(String[][] paths) {
    DefaultMutableTreeNode root = new DefaultMutableTreeNode();
    for ( String[] path : paths) {
        DefaultMutableTreeNode curr = root;
        for ( String value : path){
            DefaultMutableTreeNode next = null;
            Enumeration ce = curr.children();
            while (ce.hasMoreElements()){
                DefaultMutableTreeNode kid = 
                    (DefaultMutableTreeNode) ce.nextElement();
                if (((String)kid.getUserObject()).equals(value)){
                    next = kid;
                    break;
                }
            }
            if (next == null){
                next = new DefaultMutableTreeNode(value);
                curr.add(next);
            }
            curr = next;
        }
    }
    return root; 
}

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