JScrollPanel中没有出现多个JTree。

I am using the first example mentioned here for creating my JTree but I want to put more than one tree as root in the JscrollPanel. I just changed the layout of the box and create one more tree with the same code but when I run the program the tree is not appearing to me.

我使用这里提到的第一个例子来创建JTree，但是我想在JscrollPanel中放置不止一棵树作为根。我只是改变了框的布局，用相同的代码创建了另一棵树，但是当我运行程序时，树并没有出现在我的面前。

Here is my code

这是我的代码

import java.awt.*;
import javax.swing.*;
import javax.swing.tree.*;

public class SimpleTree extends JFrame {
  public static void main(String[] args) {
    new SimpleTree();
  }

  public SimpleTree() {
    super("Creating a Simple JTree");
    Container content = getContentPane();
    Object[] hierarchy =
      { "javax.swing",
        "javax.swing.border",
        "javax.swing.colorchooser",
        "javax.swing.event",
        "javax.swing.filechooser",
        new Object[] { "javax.swing.plaf",
                       "javax.swing.plaf.basic",
                       "javax.swing.plaf.metal",
                       "javax.swing.plaf.multi" },
        "javax.swing.table",
        new Object[] { "javax.swing.text",
                       new Object[] { "javax.swing.text.html",
                                      "javax.swing.text.html.parser" },
                       "javax.swing.text.rtf" },
        "javax.swing.tree",
        "javax.swing.undo" };
    DefaultMutableTreeNode root = processHierarchy(hierarchy);
    DefaultMutableTreeNode root2 = processHierarchy(hierarchy);
    JTree tree = new JTree(root);
    JTree tree2 = new JTree(root2);
    content.setLayout(new BoxLayout(this,BoxLayout.Y_AXIS));
    content.add(new JScrollPane(tree));
    content.add(new JScrollPane(tree2));
    setSize(getPreferredSize());
    setVisible(true);
  }

  /** Small routine that will make node out of the first entry
   *  in the array, then make nodes out of subsequent entries
   *  and make them child nodes of the first one. The process is
   *  repeated recursively for entries that are arrays.
   */

  private DefaultMutableTreeNode processHierarchy(Object[] hierarchy) {
    DefaultMutableTreeNode node =
      new DefaultMutableTreeNode(hierarchy[0]);
    DefaultMutableTreeNode child;
    for(int i=1; i<hierarchy.length; i++) {
      Object nodeSpecifier = hierarchy[i];
      if (nodeSpecifier instanceof Object[])  // Ie node with children
        child = processHierarchy((Object[])nodeSpecifier);
      else
        child = new DefaultMutableTreeNode(nodeSpecifier); // Ie Leaf
      node.add(child);
    }
    return(node);
  }
}

Could someone please help me with this. All help would be really appreciated.

有人能帮我一下吗?所有的帮助都是非常感谢的。

Thanks Ashish Tyagi

谢谢阿施施Tyagi

2 个解决方案

#1

A JScrollPane has a view to a single child component in its ViewPort.

JScrollPane具有其ViewPort中单个子组件的视图。

You could however place the 2 JScrollPane components on a single panel with say, an evenly split GridLayout(2, 1) and set the view of the JScrollPane to the new panel.

但是，您可以将两个JScrollPane组件放在一个面板上，其中包括一个均匀分割的GridLayout(2,1)，并将JScrollPane的视图设置为新面板。

Aside: You should use the ContentPane as the container for BoxLayout:

旁白:您应该使用ContentPane作为BoxLayout的容器:

content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));

#2

have to accepting that JScrollPane isn't designated to hold more than one JComponents

必须接受JScrollPane没有指定包含多个JComponents的事实吗
you can to put JPanel into JScrollPane, put required numbers of JTrees to (in JScrollPane) JPanel, maybe to use GridLayout for JPanel

您可以将JPanel放入JScrollPane，将所需的jtree数放入JPanel(在JScrollPane中)，也可以将GridLayout用于JPanel
notice possible concurency for scrollable betweens parent JScrollPane and every JScrollPanes with JTrees

注意，可在父JScrollPane和每个jtree JScrollPanes之间进行可滚动

#1