List files and directories with Jtree and File in

问题:

I want to create a very very simple file manager with JTree, but I only saw a very hard code and I want to create this script very clean and simple.

Can you help me? How do I List the directories of my computer in JTree?

回答1:

I wrote the simplest example of a file browser I could think of. It lists all of the directories and files on the C: drive on a Windows computer.

Here's the result.

And here's the code. I put everything together in one class to make it easier to paste here. You should separate the classes.

package com.ggl.testing;

import java.io.File;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;

public class FileBrowser implements Runnable {

    private DefaultMutableTreeNode root;

    private DefaultTreeModel treeModel;

    private JTree tree;

    @Override
    public void run() {
        JFrame frame = new JFrame("File Browser");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        File fileRoot = new File("C:/");
        root = new DefaultMutableTreeNode(new FileNode(fileRoot));
        treeModel = new DefaultTreeModel(root);

        tree = new JTree(treeModel);
        tree.setShowsRootHandles(true);
        JScrollPane scrollPane = new JScrollPane(tree);

        frame.add(scrollPane);
        frame.setLocationByPlatform(true);
        frame.setSize(640, 480);
        frame.setVisible(true);

        CreateChildNodes ccn = 
                new CreateChildNodes(fileRoot, root);
        new Thread(ccn).start();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new FileBrowser());
    }

    public class CreateChildNodes implements Runnable {

        private DefaultMutableTreeNode root;

        private File fileRoot;

        public CreateChildNodes(File fileRoot, 
                DefaultMutableTreeNode root) {
            this.fileRoot = fileRoot;
            this.root = root;
        }

        @Override
        public void run() {
            createChildren(fileRoot, root);
        }

        private void createChildren(File fileRoot, 
                DefaultMutableTreeNode node) {
            File[] files = fileRoot.listFiles();
            if (files == null) return;

            for (File file : files) {
                DefaultMutableTreeNode childNode = 
                        new DefaultMutableTreeNode(new FileNode(file));
                node.add(childNode);
                if (file.isDirectory()) {
                    createChildren(file, childNode);
                }
            }
        }

    }

    public class FileNode {

        private File file;

        public FileNode(File file) {
            this.file = file;
        }

        @Override
        public String toString() {
            String name = file.getName();
            if (name.equals("")) {
                return file.getAbsolutePath();
            } else {
                return name;
            }
        }
    }

}

回答2:

This is how I solved the problem when i encountered it for my project which involved a jtree to show results of my scan.

scanner function is used to initialise the parameters and call the displayDirectoryContents function

Here are some drawbacks of the method i used

• It shows empty folders as leaf nodes instead of showing them as a leaf with no children

• The model should be manually cleared by right clicking on the properties and clearing the model

  Function used

  public void displayDirectoryContents(File dir,DefaultMutableTreeNode root2) throws InterruptedException 
  {   
          DefaultMutableTreeNode newdir = new DefaultMutableTreeNode();    
  
          File[] files = dir.listFiles();  //creates array of file type for all the files found
  
          for (File file : files)
              {
                          if(file == null)
                          {
                              System.out.println("NUll directory found ");
                              continue;
                          }
                  if (file.isDirectory())
                  {
                      //file is a directory that is a folder has been dound 
  
                      if (file.listFiles()==null)
                      {
                          //skips null files
                          continue;
                      }
  
                      //gets the current model of the jtree
                      DefaultTreeModel model =(DefaultTreeModel) result.getModel();
  
                      //gets the root 
                      DefaultMutableTreeNode root=(DefaultMutableTreeNode) model.getRoot();
  
                      //generates a node newdir using filename  
                      newdir = new DefaultMutableTreeNode(file.getName());
  
                      //adds a node to the root of the jtree
                      root2.add(newdir);
  
                      //refresh the model to show the changes
                      model.reload();
  
                      //recursively calls the function again to explore the contents folder
                      displayDirectoryContents(file,newdir);
                  }
                  else
                  {
                      // Else part File is not a directory
  
  
  
                      //gets the current model of the tree
                      DefaultTreeModel model =(DefaultTreeModel) result.getModel();
  
                      //selected node is the position where the new node will be inserted
                      DefaultMutableTreeNode selectednode = root2;
  
                      DefaultMutableTreeNode newfile =new DefaultMutableTreeNode(file.getName());
  
  
                      //inserts a node newfile under selected node which is the root
                      model.insertNodeInto(newfile, selectednode, selectednode.getChildCount());
  
                      //refresh the model to show the changes
                      model.reload();
  
  
  
  
                  }
  
              }    
      }
  

  Scanner Function to initialise the above function

  public void scanner() throws InterruptedException {    
  // creates a file with the location filename
  String location ="C:\\Users\\Ashish Padalkar\\Documents";
  File currentDir = new File(location);
  
      //result is the variable name for jtree
      DefaultTreeModel model =(DefaultTreeModel) result.getModel();
      //gets the root of the current model used only once at the starting
      DefaultMutableTreeNode root=(DefaultMutableTreeNode) model.getRoot();
      //function caled
      displayDirectoryContents(currentDir,root);
  } 
  

This is my First answer on stack overflow :)