Need to run a prog on 1.4 which is running on 1.5. .....using two hashtable

Question

hello,
I've developed a program which is prefectly working on java 1.5.0 version.
but when run on java1.4.0. it gives run time error in this code.
first i'm getting error in second hashtable. put function where i'm using key as an integer.this is running on 1.5 version but have to change key as string on 1.4. but after that it is still not working properly.
I want that when i clicked on open then it must show both file
1. that have hdr extension
2. that have same name as the corrseponding .hdr file but without extension.
this program show desired result on 1.5 but on 1.4 it display only .hdr file.
pls. help me regarding this .
// class hdr file filter
import java.io.File;
import java.util.Hashtable;
import java.util.Enumeration;
import javax.swing.*;
import javax.swing.filechooser.*;
public class hdrFileFilter extends FileFilter {
private Hashtable filters = null;
private Hashtable noextensionfilter = null;
private String noextensionname=null;
private String extensionname = null;
private String description = null;
private String fullDescription = null;
private boolean useExtensionsInDescription = true;
private String fname = null;
public File noextensionarray[];
int count=0;
int counthdr=0;
int i=0;     
     //all files are accepted.
public hdrFileFilter()
     this.filters = new Hashtable();
     //Creates a file filter that accepts files with the given extension.
public hdrFileFilter(String extension)
     this(extension,null);
     //Creates a file filter that accepts the given file type.
public hdrFileFilter(String extension, String description)
     this();
     if(extension!=null)
     addExtension(extension);
     if(description!=null) setDescription(description);
     //Return true if this file should be shown in the directory pane,false if it shouldn't.
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)
          fname=f.getName();
          extensionname=fname.substring(0,fname.lastIndexOf('.'));
          counthdr+=1;
          return true;
     if(extension == null)
          noextensionfilter=new Hashtable(20);
          noextensionname=f.getName();          
          noextensionfilter.put(count,noextensionname);
          count=count + 1;
          if(noextensionfilter.get(count) == extensionname)
               noextensionarray=new File[20];
               noextensionarray=f
               System.out.println("file:" +noextensionarray[i]);
               i++;
               return true;               
     return false;
     //Return the extension portion of the file's name .
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;
     //Adds a filetype "dot" extension to filter against.
public void addExtension(String extension)
     if(filters == null)
     filters = new Hashtable(20);
     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)
                         Object nn=extensions.nextElement();
                         fullDescription += "." + nn;     
                         while (extensions.hasMoreElements())
                              fullDescription += ", ." + nn;
                    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;

Answer 1

Might be fixable if you do something like
javac -target 1.4
Bytecodes are different in 1.5 and thus not backward compatible