检查 JTree 中某个节点是否为根节点

若要检查某个节点是否是根节点，请使用 isRoot() 方法。此方法返回布尔值。如果是根节点，则返回 TRUE，否则返回 FALSE。例如，以下节点为根节点，因此将返回 TRUE −

node.isRoot()

另一个示例，以下节点不是根节点，因此将返回 FALSE −

node2.isRoot()

以下示例用于检查某个节点是否是根节点 −

示例

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);
   }
}