import java.io.File;
import java.util.Hashtable;
import java.util.Enumeration;
import javax.swing.*;
import javax.swing.filechooser.*;

public class MyFileFilter extends FileFilter {

    private static String TYPE_UNKNOWN = "Type Unknown";
    private static String HIDDEN_FILE = "Hidden File";

    private Hashtable filters = null;
    private String description = null;
    private String fullDescription = null;
    private boolean useExtensionsInDescription = true;

    public MyFileFilter() {
          this.filters = new Hashtable();
    }

    public MyFileFilter(String extension) {
          this(extension,null);
    }
    public MyFileFilter(String extension, String description) {
          this();
          if(extension!=null) addExtension(extension);
           if(description!=null) setDescription(description);
    }
   
    public MyFileFilter(String[] filters) {
          this(filters, null);
    }

    public MyFileFilter(String[] filters, String description) {
          this();
          for (int i = 0; i < filters.length; i++) {
                 addExtension(filters[i]);
          }
           if(description!=null) setDescription(description);
    }

    public boolean accept(File f) {
          if(f != null) {
              if(f.isDirectory()) {
                    return true;
              }
              String extension = getExtension(f);
              if(extension != null && filters.get(getExtension(f)) != null) {
                    return true;
              };
          }
          return false;
    }

    public String getExtension(File f) {
          if(f != null) {
              String filename = f.getName();
              int i = filename.lastIndexOf('.');
              if(i>0 && i<filename.length()-1) {
                    return filename.substring(i+1).toLowerCase();
              };
          }
          return null;
    }

    public void addExtension(String extension) {
          if(filters == null) {
              filters = new Hashtable(5);
          }
          filters.put(extension.toLowerCase(), this);
          fullDescription = null;
    }

    public String getDescription() {
          if(fullDescription == null) {
              if(description == null || isExtensionListInDescription()) {
                     fullDescription = description==null ? "(" : description + " (";
                    // build the description from the extension list
                    Enumeration extensions = filters.keys();
                    if(extensions != null) {
                        fullDescription += "." + (String) extensions.nextElement();
                        while (extensions.hasMoreElements()) {
                              fullDescription += ", ." + (String) extensions.nextElement();
                        }
                    }
                    fullDescription += ")";
              } else {
                     fullDescription = description;
              }
          }
          return fullDescription;
    }

    public void setDescription(String description) {
          this.description = description;
          fullDescription = null;
    }

    public void setExtensionListInDescription(boolean b) {
          useExtensionsInDescription = b;
          fullDescription = null;
    }

    public boolean isExtensionListInDescription() {
          return useExtensionsInDescription;
    }
}