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Check whether a node is a root node or not in JTree
To check whether a node is a root node or not, use the isRoot() method. This returns a boolean value. TRUE if the node is a root node, else FALSE is returned. For example, TRUE is returned since the following node is a root node −
node.isRoot()
Another example, FALSE is returned since the following node isn’t a root node −
node2.isRoot()
The following is an example to check whether a node is a root node or not −
Example
package my; import javax.swing.JFrame; import javax.swing.JTree; import javax.swing.tree.DefaultMutableTreeNode; public class SwingDemo { public static void main(String[] args) throws Exception { JFrame frame = new JFrame("Demo"); DefaultMutableTreeNode node = new DefaultMutableTreeNode("Website"); DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("Videos"); DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("Tutorials"); DefaultMutableTreeNode node3 = new DefaultMutableTreeNode("QA"); DefaultMutableTreeNode node4 = new DefaultMutableTreeNode("Tools"); node.add(node1); node.add(node2); node.add(node3); node.add(node4); DefaultMutableTreeNode one = new DefaultMutableTreeNode("PHP Videos"); DefaultMutableTreeNode two = new DefaultMutableTreeNode("HTML5 Videos"); DefaultMutableTreeNode three = new DefaultMutableTreeNode("BlockchainVideos"); DefaultMutableTreeNode four = new DefaultMutableTreeNode("Java"); DefaultMutableTreeNode five = new DefaultMutableTreeNode("DBMS"); DefaultMutableTreeNode six = new DefaultMutableTreeNode("CSS"); DefaultMutableTreeNode seven = new DefaultMutableTreeNode("MongoDB"); DefaultMutableTreeNode eight = new DefaultMutableTreeNode("Python QA"); DefaultMutableTreeNode nine = new DefaultMutableTreeNode("jQuery QA"); DefaultMutableTreeNode ten = new DefaultMutableTreeNode("Photo Editing Tool"); node1.add(one); node1.add(two); node1.add(three); node2.add(four); node2.add(five); node2.add(six); node2.add(seven); node3.add(eight); node3.add(nine); node4.add(ten); JTree tree = new JTree(node); for (int i = 0; i < tree.getRowCount(); i++) { tree.expandRow(i); } tree.putClientProperty("JTree.lineStyle", "Angled"); System.out.println("Number of children of node1 (Videos) = " +node1.getChildCount()); System.out.println("Number of children of node2 (Tutorials) = " +node2.getChildCount()); System.out.println("Number of children of node3 (QA) = " +node3.getChildCount()); System.out.println("Number of children of node4 (Tools) = " +node4.getChildCount()); System.out.println("Depth of Tree = " + node.getDepth()); System.out.println("Count of Tree Leaves(root node) = " +node.getLeafCount()); System.out.println("Count of Tree Leaves(node1) = " +node1.getLeafCount()); System.out.println("Count of Tree Leaves(node2) = " +node2.getLeafCount()); System.out.println("Count of Tree Leaves(node3) = " +node3.getLeafCount()); System.out.println("Count of Tree Leaves(node3) = " +node4.getLeafCount()); System.out.println("Is node the root node? = " + node.isRoot()); System.out.println("Is node1 the root node? = " + node1.isRoot()); System.out.println("Is node2 the root node? = " + node2.isRoot()); System.out.println("Is node3 the root node? = " + node3.isRoot()); System.out.println("Is node4 the root node? = " + node4.isRoot()); tree.setRowHeight(25); frame.add(tree); frame.setSize(600,450); frame.setVisible(true); } }
Output
Following is our JTree −
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