JTree在重新加载后避免崩溃

1 回答

• 2

  考虑使用DefaultTreeModel#insertNodeInto(DefaultMutableNode, DefaultMutableNode, int)，它应该通知 JTree 表新节点可用，导致 JTree 更新，但不应影响树的当前展开状态

  此示例基于How to use trees中的示例

  import java.awt.BorderLayout;
  import javax.swing.JFrame;
  import javax.swing.JPanel;
  import javax.swing.JScrollPane;
  import javax.swing.UIManager;
  
  import javax.swing.JTree;
  import javax.swing.tree.DefaultMutableTreeNode;
  import javax.swing.tree.TreeSelectionModel;
  import javax.swing.event.TreeSelectionEvent;
  import javax.swing.event.TreeSelectionListener;
  
  import java.awt.GridLayout;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  import javax.swing.JButton;
  import javax.swing.UnsupportedLookAndFeelException;
  import javax.swing.tree.DefaultTreeModel;
  import javax.swing.tree.TreePath;
  
  public class TestTree extends JPanel {
  
      private JTree tree;
      private DefaultTreeModel model;
      private JButton btnAdd;
      private int childCount;
  
      public TestTree() {
          super(new BorderLayout());
  
          //Create the nodes.
          DefaultMutableTreeNode top = new DefaultMutableTreeNode("The Java Series");
          createNodes(top);
  
          model = new DefaultTreeModel(top);
  
          //Create a tree that allows one selection at a time.
          tree = new JTree(model);
          tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
  
          //Create the scroll pane and add the tree to it. 
          JScrollPane treeView = new JScrollPane(tree);
  
          //Add the split pane to this panel.
          add(treeView);
  
          btnAdd = new JButton("Add");
          btnAdd.addActionListener(new ActionListener() {
              @Override
              public void actionPerformed(ActionEvent e) {
                  TreePath treePath = tree.getSelectionPath();
                  if (treePath != null) {
                      DefaultMutableTreeNode node = (DefaultMutableTreeNode) treePath.getLastPathComponent();
                      DefaultMutableTreeNode child = new DefaultMutableTreeNode("Child " + (++childCount));
                      model.insertNodeInto(child, node, node.getChildCount());
                  }
              }
          });
  
          add(btnAdd, BorderLayout.SOUTH);
      }
  
      private class BookInfo {
  
          public String bookName;
  
          public BookInfo(String book) {
              bookName = book;
          }
  
          public String toString() {
              return bookName;
          }
      }
  
      private void createNodes(DefaultMutableTreeNode top) {
          DefaultMutableTreeNode category = null;
          DefaultMutableTreeNode book = null;
  
          category = new DefaultMutableTreeNode("Books for Java Programmers");
          top.add(category);
  
          //original Tutorial
          book = new DefaultMutableTreeNode(new BookInfo("The Java Tutorial: A Short Course on the Basics"));
          category.add(book);
  
          //Tutorial Continued
          book = new DefaultMutableTreeNode(new BookInfo("The Java Tutorial Continued: The Rest of the JDK"));
          category.add(book);
  
          //JFC Swing Tutorial
          book = new DefaultMutableTreeNode(new BookInfo("The JFC Swing Tutorial: A Guide to Constructing GUIs"));
          category.add(book);
  
          //Bloch
          book = new DefaultMutableTreeNode(new BookInfo("Effective Java Programming Language Guide"));
          category.add(book);
  
          //Arnold/Gosling
          book = new DefaultMutableTreeNode(new BookInfo("The Java Programming Language"));
          category.add(book);
  
          //Chan
          book = new DefaultMutableTreeNode(new BookInfo("The Java Developers Almanac"));
          category.add(book);
  
          category = new DefaultMutableTreeNode("Books for Java Implementers");
          top.add(category);
  
          //VM
          book = new DefaultMutableTreeNode(new BookInfo("The Java Virtual Machine Specification"));
          category.add(book);
  
          //Language Spec
          book = new DefaultMutableTreeNode(new BookInfo("The Java Language Specification"));
          category.add(book);
      }
  
      /**
       * Create the GUI and show it. For thread safety, this method should be
       * invoked from the event dispatch thread.
       */
      private static void createAndShowGUI() {
          try {
              UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
          } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
              ex.printStackTrace();
          }
  
          //Create and set up the window.
          JFrame frame = new JFrame("TreeDemo");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
          //Add content to the window.
          frame.add(new TestTree());
  
          //Display the window.
          frame.pack();
          frame.setVisible(true);
      }
  
      public static void main(String[] args) {
          //Schedule a job for the event dispatch thread:
          //creating and showing this application's GUI.
          javax.swing.SwingUtilities.invokeLater(new Runnable() {
              public void run() {
                  createAndShowGUI();
              }
          });
      }
  
  }
  

  回复于 2024-04-20T10:11:46+08:00