MAP Problem with JAVA and Sqlite database

I have another question for you: The code below does the following

1. For each file in a folder

2. Open the file and read its contents

3. Take and divide each line into tokens

4. Save each token (word) in a hasMap

5. Prepare a database query (Select form words ...)

6. For each match found between the tokens and the words contained in the database Write 1.0, if true, otherwise 0.0;

The problem arises at this point:

try{
    while (rs_mail.next()) {
        if(result_m.contains(rs_mail.getString("voc_w").toString()))  //HERE I GET THE ERROR! java.lang.NullPointerException
            out_final.print("1.0;"); 
        else
            out_final.print("0.0;"); 
    }//Close While
}       //Close TRY
finally{
    rs_mail.close();
    //result_m.clear();
    mail.clear(); //Clear MAP
}

Below the complete code:

String path ="C:/Users/.../file";
File currentDIR = new File("C:/Users/.../file");
File files_mail[]=currentDIR.listFiles();
String tmp_mail="";

// prepares the file tmpTraning.txt to receive value 1.0, 0.0 obtained by comparison with database
PrintWriter out_final=null;
File ff=new File("C:/Users/.../tmpTraning.txt");

//Seach for File in DIR
for( File fX : files_mail ){
    String name_Filex = fX.getName();
    FileReader fr = null;
    BufferedReader fINx = null;
    String sx;
    //Create MAP 
    Map<String, Set<String>> mail = new HashMap<String, Set<String>>();
    //Open File
    try{
        Set<String> sq = new HashSet<String>();

        fr = new FileReader(path+"/"+name_Filex);
        fINx = new BufferedReader(fr);
        sx = fINx.readLine();

        //scroll the file
        while(sx != null) {
            StringTokenizer stq = new StringTokenizer(sx);
            while(stq.hasMoreTokens()) { //Extract form line the single word
                tmp_mail = stq.nextToken();

                sq.add(tmp_mail.toString().toLowerCase()); //add the word to sq -> HashMap
                mail.put(nome_Filex, sq);

            }// Close st.hasMoreTokens()

            sx = fINx.readLine();
        } //Close  while for scroll File
        fr.close(); //Close fileReader
        sq.clear(); //Clear HasSet

    } //Close il TRAY
    catch (FileNotFoundException ex) {
        ex.printStackTrace();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

    Set<String> result_m = mail.get(name_Filex);
    ResultSet rs_mail = stmt.executeQuery("SELECT DISTINCT voc.words as voc_w FROM voc_words as voc");

    //Prepare for writing on the file " tmpTraning.txt " 
    OutputStreamWriter fout_f = new OutputStreamWriter(new FileOutputStream(ff,true));
    out_final = new PrintWriter(fout_f);

    try{
        while (rs_mail.next()) {
            //If the word extract from the database is in MAP (name_Filex) then print 1.0; on the file tmpTraning.txt
            if(result_m.contains(rs_mail.getString("voc_w").toString()))  //HERE I GET THE ERROR! java.lang.NullPointerException
                out_final.print("1.0;"); 
            else
                //else print 0.0;
                out_final.print("0.0;"); 
        }
    }       //Close TRY
    finally{
        rs_mail.close();
        //result_m.clear();
        mail.clear(); //Clear MAP
    }

    out_final.println(""); //Send CR char ASCII to set the coursor for the next file on the new line
    out_final.close();
    out_final.flush();
} // End SCAN DIR

Thanks for any advice!

Code changes - print the contents of result_m:

String path ="...";
File currentDIR = new File("...");
File files_mail[]=currentDIR.listFiles();
String tmp_mail="";

// prepares the file tmpTraning.txt to receive value 1.0, 0.0 obtained by comparison with database
PrintWriter out_final=null;
File ff=new File("...");

//Seach for File in DIR
for( File fX : currentDIR.listFiles() ){
    String name_Filex = fX.getName();

    String sx;
    //Create MAP 
    Map<String, Set<String>> mail = new HashMap<String, Set<String>>();
    //Open File
    try{
        Set<String> sq = new HashSet<String>();
        BufferedReader fINx = new BufferedReader(new FileReader(fX));
        sx = fINx.readLine();
        //scroll the file
        while(sx != null) {
            StringTokenizer stq = new StringTokenizer(sx);
            while(stq.hasMoreTokens()) { //Extract form line the single word
                tmp_mail = stq.nextToken();

                sq.add(tmp_mail.toString().toLowerCase()); //add the word to sq -> HashMap
                mail.put(name_Filex, sq);

            }// Close st.hasMoreTokens()

            sx = fINx.readLine();
        } //Close  while for scroll File
        fr.close(); //Close fileReader
        sq.clear(); //Clear HasSet

    } //Close il TRAY
    catch (FileNotFoundException ex) {
        ex.printStackTrace();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

    /*
     * print the contents of  result_m
     */

    System.out.println("----- START FILE -----");
    Set<String> result_m = mail.get(name_Filex);
    Object[] toArray_m = mail.get(name_Filex).toArray();
    for (int ncc=0; ncc<result_m.size();ncc++){
        System.out.println(toArray_m[ncc]);
    }
    System.out.println("----- END  FILE  -----");


} // End SCAN DIR

if the file read by the program contains blank lines (no char, no string), it saves a null value