Engineeringserver.com | How to create and use JTree’s

How to create and use JTree’s

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05.03.2008 by HappyFace in Java, Languages

A small demo I wrapped up that shows you how to use a JTree. The demo shows a JTree and a message of the selected item on the bottom of the JFrame.

PLAIN TEXT

JAVA:

import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTree;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreeSelectionModel;
public class TreeDemo extends JFrame implements TreeSelectionListener{
JTree tree;
DefaultMutableTreeNode root, child1,child2,child3, item1,item2;
JLabel message;
public TreeDemo(){
setTitle("TreeDemo :: www.engineeringserver.com");
getContentPane().setLayout(null);
root = new DefaultMutableTreeNode("root");
child1 = new DefaultMutableTreeNode("Child1");
child2 = new DefaultMutableTreeNode("Child2");
child3 = new DefaultMutableTreeNode("Child3");
item1 = new DefaultMutableTreeNode("item1");
item2 = new DefaultMutableTreeNode("item2");
root.add(child1);
root.add(child2);
root.add(child3);
child2.add(item1);
child2.add(item2);
tree = new JTree(root);
tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
expandAll(tree);
tree.addTreeSelectionListener(this);
tree.setBounds(0,0,400,200);
message = new JLabel("Selected: ");
message.setBounds(0,200,200,20);
add(tree);
add(message);
setLocationRelativeTo(null);
setResizable(false);
setSize(400,250);
setVisible(true);
}
public static void main(String[] args){
new TreeDemo();
}
public void valueChanged(TreeSelectionEvent e) {
DefaultMutableTreeNode node = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();
Object nodeInfo = node.getUserObject();
message.setText("Selected: " + nodeInfo);
}
public void expandAll(JTree tree) {
int totalElements = 0;
while (totalElements <tree.getRowCount()) {
tree.expandRow(totalElements);
totalElements++;
}
}
}