JAVA - How to access objects of ArrayList from JTree

Question

I am having issues accessing the elements of my ArrayList just clicking in the corresponding node. This is the first time I am using this, I have searched for a lot of different tutorials but I could not solve my issue. This is what I have so far:

class Animal: Just constructor with diffrent arguments, setters and getters.
class MainClass: ArrayList of animal. Main is running here.

class Menu: JFrame designed with NetBeans. To get the elements of the ArrayList I use the following code:

public void refreshTree(){

    root = new DefaultMutableTreeNode("Animals");
    children1 = new DefaultMutableTreeNode("Carnivores");

    root.add(children1);

    mainTree = new JTree(root);

    List<Animal> animals = mainClass.returnList();     

    for(Animal animal: animals){
        DefaultMutableTreeNode node = new DefaultMutableTreeNode(animal);
        children1.add(node);
    }

    jScrollPane2.setViewportView(mainTree);
}

Everytime that I add or remove an element from the ArrayList, I use refreshTree() method in order to get an updated version of my ArrayList.

In my Menu class I have also different JTextPanel for the different attributes of the animals.

What I need to do (I will not copy the code I have right now, because I think has not sense) is to be able to click in one node, so the different attributes of the animal are loaded in the JTextPanel, so if I modify the values, they will be changed in the object as well.

I know I should use something like:

int value = textPanel.getText();

And then use the setters of my class Animal.

My problem is how I access to that specific animal just clicking in the JTree?

[This is one way](http://stackoverflow.com/questions/12847904/double-click-a-jtree-node-and-get-its-name/12848028#12848028), another way might use the TreeSelectionModel to detect changes in the dejection which might be a cleaner solution as it includes the possibility of the user the key board. The DefaultMutatableTreeNode provides the associated object via the userObject property — MadProgrammer, Jun 09 '16 at 10:51
Of and I wouldn't reconstruct the tree every time you want to add/remove elements, I'd make use of the TreeModel to generate update events — MadProgrammer, Jun 09 '16 at 10:58
And [for a larger example](http://stackoverflow.com/questions/31911382/i-would-like-to-put-the-information-to-add-in-jpanel-jscrollpane-when-you-click/31911449#31911449) — MadProgrammer, Jun 09 '16 at 11:12

score 2 · Accepted Answer · edited Jun 09 '16 at 14:23

You can do like below. Hope it helps you to progress.

JTree tree = new JTree();
DefaultMutableTreeNode root = new DefaultMutableTreeNode("Animals");
DefaultTreeModel model = new DefaultTreeModel(root);

tree.setModel(model);
root.add(new DefaultMutableTreeNode(new Animal("Dog","ACS")));
root.add(new DefaultMutableTreeNode(new Animal("Cat","BCS")));
root.add(new DefaultMutableTreeNode(new Animal("Lion","FCS")));

DefaultTreeSelectionModel sModel = new DefaultTreeSelectionModel(); 

sModel.setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
tree.setSelectionModel(sModel);
tree.addTreeSelectionListener(new TreeSelectionListener() {

    @Override
    public void valueChanged(TreeSelectionEvent selection) {
        DefaultMutableTreeNode selectedNode = (DefaultMutableTreeNode)selection.getPath().getLastPathComponent();
        if(selectedNode.isLeaf()) {
            Animal animal = (Animal)selectedNode.getUserObject();
        }
    }
});

Thank you so much for the help. I will check through that code and hopefully will be able to solve my issue. Best regards — Jose Lara, Jun 09 '16 at 18:50

JAVA - How to access objects of ArrayList from JTree

1 Answers1