如何使用JTree显示JPanel目录中的文件？

我正在使用Swing开发GUI。 GUI以这样的方式实现：当用户想要加载一组文本文件时，然后应该打开文件选择器对话框并且用户选择存在所有文件的目录。 现在，我想使用JTree将所选目录中的所有文件列入JScrollPane。 我正在使用此示例在我的代码中实现JTree： http ： //www.java2s.com/Code/Java/File-Input-Output/FileTreeDemo.htm

但是，在选择目录后，JTree不会显示在JPanel中。 我已将JTree代码放在actionPerformed（）方法中。 我不确定这是不是正确的方法。

这是代码：

public void actionPerformed(ActionEvent e) { //Handle open button action. if (e.getSource() == OpenFileButton) { int returnVal = fc.showOpenDialog(GUIMain.this); if (returnVal == JFileChooser.APPROVE_OPTION) { file = fc.getSelectedFile(); System.out.println(file); File[] filesInDirectory = file.listFiles(); SortFile sf = new SortFile(); // Calls sortByNumber method in class SortFile to list the files number wise filesInDirectory = sf.sortByNumber(filesInDirectory); FileTreeModel model = new FileTreeModel(file); tree = new JTree(); tree.setModel(model); spectralFilesScrollPane = new JScrollPane(tree); // add(BorderLayout.CENTER, spectralFilesScrollPane); spectralFilesScrollPane.setVerticalScrollBarPolicy( JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); spectralFilesScrollPane.setPreferredSize(new Dimension(250, 145)); spectralFilesScrollPane.setMinimumSize(new Dimension(10, 10)); spectralFilesScrollPane.setBorder( BorderFactory.createCompoundBorder( BorderFactory.createTitledBorder("Spectral Files"), BorderFactory.createEmptyBorder(5, 5, 5, 5))); content.add(spectralFilesScrollPane); spectralFilesScrollPane.setVisible(true); } } } 

FileTreeModel.java类

 import javax.swing.event.TreeModelListener; import javax.swing.tree.TreeModel; import javax.swing.*; import javax.swing.tree.TreePath; import java.io.File; /** * The methods in this class allow the JTree component to traverse * the file system tree, and display the files and directories. **/ class FileTreeModel implements TreeModel { // We specify the root directory when we create the model. protected File root; public FileTreeModel(File root) { System.out.println("I am in FileTree Model"); this.root = root; } // The model knows how to return the root object of the tree public Object getRoot() { return root; } // Tell JTree whether an object in the tree is a leaf or not public boolean isLeaf(Object node) { return ((File)node).isFile(); } // Tell JTree how many children a node has public int getChildCount(Object parent) { String[] children = ((File)parent).list(); if (children == null) return 0; System.out.println("printing child length:" + children.length); return children.length; } // Fetch any numbered child of a node for the JTree. // Our model returns File objects for all nodes in the tree. The // JTree displays these by calling the File.toString() method. public Object getChild(Object parent, int index) { String[] children = ((File)parent).list(); if ((children == null) || (index >= children.length)) return null; return new File((File) parent, children[index]); } // Figure out a child's position in its parent node. public int getIndexOfChild(Object parent, Object child) { String[] children = ((File)parent).list(); if (children == null) return -1; String childname = ((File)child).getName(); for(int i = 0; i < children.length; i++) { if (childname.equals(children[i])) return i; } return -1; } // This method is only invoked by the JTree for editable trees. // This TreeModel does not allow editing, so we do not implement // this method. The JTree editable property is false by default. public void valueForPathChanged(TreePath path, Object newvalue) {} // Since this is not an editable tree model, we never fire any events, // so we don't actually have to keep track of interested listeners. public void addTreeModelListener(TreeModelListener l) {} public void removeTreeModelListener(TreeModelListener l) {} } 

重新validation内容容器后，GUI如下所示：

Answer 1

您尚未重新validation包含content Container。 在actionPerformed方法的末尾添加行

 //content.invalidate(); content.revalidate(); content.repaint();