Java Swing How to - Populate tree with package listing

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Question

We would like to know how to populate tree with package listing.

Answer

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.io.File;
import java.util.Collections;
import java.util.Vector;
/*from w ww.  j ava 2 s.c o m*/
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;

public class Main extends JPanel {
  public Main(File dir) {
    setLayout(new BorderLayout());
    JTree tree = new JTree(addNodes(null, dir));
    tree.addTreeSelectionListener(e -> {
      DefaultMutableTreeNode node = (DefaultMutableTreeNode) e.getPath()
          .getLastPathComponent();
      System.out.println("You selected " + node);
    });
    JScrollPane scrollpane = new JScrollPane();
    scrollpane.getViewport().add(tree);
    add(BorderLayout.CENTER, scrollpane);
  }

  private DefaultMutableTreeNode addNodes(DefaultMutableTreeNode curTop,
      File dir) {
    String curPath = dir.getPath();
    DefaultMutableTreeNode curDir = new DefaultMutableTreeNode(curPath);
    if (curTop != null) {
      curTop.add(curDir);
    }
    Vector<String> ol = new Vector<String>();
    String[] tmp = dir.list();
    for (int i = 0; i < tmp.length; i++) {
      ol.addElement(tmp[i]);
    }
    Collections.sort(ol, String.CASE_INSENSITIVE_ORDER);
    File f;
    Vector<Object> files = new Vector<Object>();
    for (int i = 0; i < ol.size(); i++) {
      String thisObject = ol.elementAt(i);
      String newPath;
      if (curPath.equals(".")) {
        newPath = thisObject;
      } else {
        newPath = curPath + File.separator + thisObject;
      }
      if ((f = new File(newPath)).isDirectory()) {
        addNodes(curDir, f);
      } else {
        files.addElement(thisObject);
      }
    }
    for (int fnum = 0; fnum < files.size(); fnum++) {
      curDir.add(new DefaultMutableTreeNode(files.elementAt(fnum)));
    }
    return curDir;
  }

  @Override
  public Dimension getMinimumSize() {
    return new Dimension(200, 400);
  }

  @Override
  public Dimension getPreferredSize() {
    return new Dimension(200, 400);
  }

  public static void main(final String[] av) {
    JFrame frame = new JFrame();
    Container cp = frame.getContentPane();
    cp.add(new Main(new File(".")));
    frame.pack();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
}

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