How can i cast array of string to int ?

Question

                   while(st.hasMoreTokens()){
                              test[count] = st.nextToken();
                              count++;
                      }Since token deal with string, i have to pass them into String of array, but how can i convert all of them to int to perform arithmetic operation?

Answer 1

     public static void main (String[] args) throws IOException{
           DataInputStream dis = null;
             String dbRecord = null;
             int tokenCount = 0;
             int numOfQuestion = 0;
             int questionnAireNum = 0;
             int postCode = 0;
             int age = 0;
             int gender = 0;
             String [] response = new String[10];
                File f = new File("polldata.txt");
                FileInputStream fis = new FileInputStream(f); 
                BufferedInputStream bis = new BufferedInputStream(fis); 
                dis = new DataInputStream(bis);
                // read the first record of the database
                while ( (dbRecord = dis.readLine()) != null) {
                   StringTokenizer st = new StringTokenizer(dbRecord, ",");
                   tokenCount = st.countTokens();
                   numOfQuestion = tokenCount-4;
                   String rquestionNum = st.nextToken();
                   questionnAireNum = Integer.parseInt(rquestionNum);
                   String rpostCode = st.nextToken();
                   postCode = Integer.parseInt(rpostCode);
                   String rAge  = st.nextToken();
                   age = Integer.parseInt(rAge);
                   String rGender = st.nextToken();
                   gender = Integer.parseInt(rGender);
                   for(int i=0; i<numOfQuestion;i++){
                        response[i] = st.nextToken();
                   }hi how come when i cast the string as int it prompt me error as shown below ? I wonder what causes this because this is normally how i cast string to int, somehow it won work this way with token.
Exception in thread "main" java.lang.NumberFormatException: For input string: " 3"
     at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
     at java.lang.Integer.parseInt(Integer.java:447)
     at java.lang.Integer.valueOf(Integer.java:553)
     at test.main(test.java:43)