JTree不顯示添加的節點

Question

我試圖創建我的第一個JTree，但是當我嘗試將我的節點添加到樹中時，所做的更改未生效，並且顯示的所有內容都是其中包含一些默認節點的樹（顏色，運動，食物）。

我的主面板中的代碼，其中樹所在：

import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.UIManager; 
public class Scenario1Panel extends JPanel 
{ 

/** 
* 
*/ 
private static final long serialVersionUID = 1L; 

public Scenario1Tree scenario1Tree; 

public Scenario1Panel() 
{ 
    scenario1Tree = new Scenario1Tree(); 
    add(scenario1Tree); 
} 
public static void main(String args[]) 
{ 
    try 
    { 
     String lookAndFeel = UIManager.getSystemLookAndFeelClassName(); 
     System.out.println(lookAndFeel); 
     UIManager.setLookAndFeel(lookAndFeel); 
    } 
    catch(Exception e) 
    { 
     System.out.println("couldn't get that LookAndFeel"); 
    } 

    Scenario1Panel mgr = new Scenario1Panel(); 

    JFrame frame = new JFrame(); 

    frame.add(mgr); 
    frame.pack(); 
    frame.setVisible(true); 

} 

}

我的樹代碼：

import javax.swing.JScrollPane; 
import javax.swing.JTree; 
import javax.swing.UIManager; 
import javax.swing.tree.DefaultMutableTreeNode; 
import javax.swing.tree.TreeSelectionModel; 
public class Scenario1Tree extends JTree 
{ 
/** 
* 
*/ 
private static final long serialVersionUID = 1L; 

private JTree tree; 

public Scenario1Tree() 
{ 
    DefaultMutableTreeNode top = new DefaultMutableTreeNode("Scenario1"); 
    createNodes(top); 
    tree = new JTree(top); 

    //Create a tree that allows one selection at a time. 
    tree.getSelectionModel().setSelectionMode 
     (TreeSelectionModel.SINGLE_TREE_SELECTION); 

    //Create the scroll pane and add the tree to it. 
    JScrollPane treeView = new JScrollPane(tree); 


} 

private void createNodes(DefaultMutableTreeNode top) { 
    DefaultMutableTreeNode loginUser1 = null; 
    DefaultMutableTreeNode addNewUsers = null; 
    DefaultMutableTreeNode addNewUsersBreakout = null; 

    loginUser1 = new DefaultMutableTreeNode("Login User 1"); 
    top.add(logintUser1); 

    addNewUsers = new DefaultMutableTreeNode("Add New Users"); 
    top.add(addNewUsers); 

    addNewUsersBreakout = new DefaultMutableTreeNode("Add User2"); 
    addNewUsers.add(addNewUsersBreakout); 
    addNewUsersBreakout = new DefaultMutableTreeNode("Add User3"); 
    addNewUsers.add(addNewUsersBreakout); 
    addNewUsersBreakout = new DefaultMutableTreeNode("Add User4"); 
    addNewUsers.add(addNewUsersBreakout); 
    addNewUsersBreakout = new DefaultMutableTreeNode("Add User5"); 
    addNewUsers.add(addNewUsersBreakout); 

} 

public static void main(String args[]) 
{ 
    try 
    { 
     String lookAndFeel = UIManager.getSystemLookAndFeelClassName(); 
     System.out.println(lookAndFeel); 
     UIManager.setLookAndFeel(lookAndFeel); 
    } 
    catch(Exception e) 
    { 
     System.out.println("couldn't get that LookAndFeel"); 
    } 

    Scenario1Tree tree = new Scenario1Tree(); 

    JFrame frame = new JFrame(); 

    frame.add(tree); 
    frame.pack(); 
    frame.setVisible(true); 

} 

}

可能有人請解釋一下我的」米做錯了嗎？

Answer 1

在的Scenario1Tree代替JTree實例創建呼叫

setModel(new DefaultTreeModel(top)); 

事實上，你並不需要JTree實例都沒有。

Answer 2

您正在創建一個JTree太多。您將所有節點添加到JTree變量中，但是對於顯示的樹使用JTree擴展類，後者沒有添加節點。

我建議你沒有擴展JTree類，而是給它一個方法，比如getTree()，它返回JTree的時間和地點。

即

// get rid of extends JTree 
public class Scenario1Tree // extends JTree 
{ 
private static final long serialVersionUID = 1L; 

private JTree tree; 

public Scenario1Tree() 
{ 
    DefaultMutableTreeNode top = new DefaultMutableTreeNode("Scenario1"); 
    createNodes(top); 
    tree = new JTree(top); 

    tree.getSelectionModel().setSelectionMode 
     (TreeSelectionModel.SINGLE_TREE_SELECTION); 

    // JScrollPane treeView = new JScrollPane(tree); 

} 

public JTree getTree() { 
    return tree; 
}