Error updating code to 1.5

I just need some help figuring out how to solve this, cause I'm stuck.

Error: java.lang.Comparable cannot be inherited with different
arguments: <> and <java.io.File>

<------------ Code ------------>

import java.util.*;
import java.io.File;
import java.text.Collator;

import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;
import javax.swing.event.TreeModelListener;
import javax.swing.event.TreeModelEvent;
  private class FileTreeNode extends File implements Comparable
  {
    public FileTreeNode(File file)
    {
      super(file, "");
    }

    /**
     * Compare two FileTreeNode objects so that directories
     * are sorted first.
     *
     * @param object Object to compare to.
     * @return Compare identifier.
     */
    public int compareTo (Object object)
    {
      File file1 = this;
      File file2 = (File) object;

      Collator collator = Collator.getInstance();

      if (file1.isDirectory() && file2.isFile())
        return -1;
      else if (file1.isFile() && file2.isDirectory())
        return +1;
      else
        return collator.compare(file1.getName(), file2.getName());
    }