我们能否使用 Java 来防止 JTree 中的节点和子节点折叠?\n


是的,我们可以使用 setExpandedState() 方法来防止 JTree 中的节点和子节点折叠。此方法设置此 JTree 的展开状态。如果 state 为 true,则所有路径和路径的父节点都被标记为展开。

以下是一个使用 Java 来防止 JTree 中的节点和子节点折叠的示例 -

示例

package my;
import javax.swing.JFrame;
import javax.swing.JTree;
import javax.swing.text.Position;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreePath;
public class SwingDemo {
   public static void main(String[] args) throws Exception {
      JFrame frame = new JFrame("Demo");
      DefaultMutableTreeNode node = new DefaultMutableTreeNode("Project");
      DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("App");
      DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("Website");
      DefaultMutableTreeNode node3 = new DefaultMutableTreeNode("WebApp");
      node.add(node1);
      node.add(node2);
      node.add(node3);
      DefaultMutableTreeNode one = new DefaultMutableTreeNode("Learning website");
      DefaultMutableTreeNode two = new DefaultMutableTreeNode("Business website");
      DefaultMutableTreeNode three = new DefaultMutableTreeNode("News publishing website");
      DefaultMutableTreeNode four = new DefaultMutableTreeNode("Android app");
      DefaultMutableTreeNode five = new DefaultMutableTreeNode("iOS app");
      DefaultMutableTreeNode six = new DefaultMutableTreeNode("Editor WebApp");
      node1.add(one);
      node1.add(two);
      node1.add(three);
      node2.add(four);
      node2.add(five);
      node3.add(six);
      JTree tree = new JTree(node) {
         protected void setExpandedState(TreePath path, boolean state) {
            if (state) {
               super.setExpandedState(path, state);
            }
         }
      };
      for (int i = 0; i < tree.getRowCount(); i++) {
         tree.expandRow(i);
      }
      tree.putClientProperty("JTree.lineStyle", "Angled");
      int begnRow = 0;
      String prefix = "A";
      TreePath treePath = tree.getNextMatch(prefix, begnRow, Position.Bias.Forward);
      System.out.println("Node = "+treePath);
      tree.setRowHeight(25);
      frame.add(tree);
      frame.setSize(550,400);
      frame.setVisible(true);
   }
}

输出

更新于: 30-Jul-2019

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