"Exception in thread "main" java.lang.NumberFormatException"error..pls help

Question

Hi,
I'm trying to run a program I've written but keeping getting this error:
Exception in thread "main" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:994)
at java.lang.Double.parseDouble(Double.java:482)
at data.newLineToRead(data.java:21)
at data.data(data.java:34)
at train.main(train.java:86)
I'm not quite sure where I'm going wrong.I've included the data class and train class.Could someone pls help me.
Thanks a lot.
Data Class:
import java.io.*;
import java.util.*;
public class data{
        private static parameter par;
        private static double[][] x=new double[par.n()][par.D()];
        public static double[] t=new double[par.n()];
        public static void newLineToRead(String LineToRead,int n){
        int d=0;
        String stringToRead=new String();
                for(int i=0;i<=LineToRead.length();i++){
                        StringTokenizer str = new StringTokenizer (stringToRead,"/t");
                        String[] strtemp = new String[str.countTokens()];
                                while (str.hasMoreTokens()){
                                x[n][d++] = Double.parseDouble(str.nextToken());
                                d++;
                                System.out.println(x[n][d++]);
                        stringToRead=new String();
                t[n]=Double.parseDouble(stringToRead);
                x[n][par.d()]=1.0;
        public static void data() throws IOException{
        DataInputStream in=null;
                try{
                        in=new DataInputStream(new FileInputStream(par.f()));
                        for(int n=0;n<par.n();n++){
                        String LineToRead=in.readLine();
                                if(LineToRead.length()==0){
                                        System.out.println("Remove empty lines");
                                else{
                                        newLineToRead(LineToRead,n);
                }finally{if(in!=null){in.close();}}
        public static double x(int n,int d){return x[n][d];}
        public static double t(int n){return t[n];}
}Train Class
import java.io.*;
import java.util.*;
public class train{
         private static parameter       par;
         private static data            dat;
         private static model           mod;
         private static response        resp;
         private static void error(String msg){
                System.out.println(msg);
                System.exit(1);
         private static void check(){
            if(par.f().length()==0)
                error("No filename of input vectors!");
            if(par.n()==0)
                error("No number of input vectors!");
            if(par.d()==0)
                error("No number of input variables!");
            if(par.d()>par.D())
                error("Dimension is larger than 100!");
          private static void usage(){
            System.out.println("Non-default parameters==========================");
            System.out.println("-f filename of input vectors");
            System.out.println("-n number of input vectors");
            System.out.println("-d number of input variables");
            System.out.println("Default parameters==========================");
            System.out.println("-R regularisation constant (must be positive and the default value is 0.0)");
            System.out.println("-S epsilon criterion for stopping a learning process (default value is 0.001)");
            System.out.println("-C maximum learning cycle (default value is 10000)");
                  public static void main(String[] argv){
                        if(argv.length==0){
                                System.out.println("Command line is <Java [-cp path] train parameters>");
                                usage();
                                System.exit(1);
                        if(argv.length==1 && argv[0].equals("help")==true){
                                usage();
                                System.exit(1);
                        par.nin(0); par.din(0); par.Rin(0.0); par.Cin(10000); par.Sin(0.001);
for(int i=0;i<argv.length;i++){
                                        if(argv.equals("-f")==true){
if((i+1)==argv.length)
error("miss the para");
par.fin(argv[i+1]);
i++;
else if(argv[i].equals("-d")==true){
if((i+1)==argv.length)
error("miss the para");
par.din(Integer.parseInt(argv[i+1]));
i++;
else if(argv[i].equals("-n")==true){
if((i+1)==argv.length)
error("miss the para");
par.nin(Integer.parseInt(argv[i+1]));
i++;
else if(argv[i].equals("-S")==true){
if((i+1)==argv.length)
error("miss the para");
par.Sin(Integer.parseInt(argv[i+1]));
i++;
else if(argv[i].equals("-C")==true){
if((i+1)==argv.length)
error("miss the para");
par.Cin(Integer.parseInt(argv[i+1]));
i++;
else if(argv[i].equals("-R")==true){
if((i+1)==argv.length)
error("miss the para");
par.Rin(Double.parseDouble(argv[i+1]));
i++;
else error("Unkown token");
check();
try {
dat.data();
}catch(IOException e) { System.err.println(e.toString()); }
try {
mod.model();
}catch(IOException e) { System.err.println(e.toString()); }
try {
resp.record();
}catch(IOException e){ System.err.println(e.toString()); }

Answer 1

String stringToRead=new String();
                for(int i=0;i<=LineToRead.length();i++){
                        StringTokenizer str = new StringTokenizer (stringToRead,"/t");
                        String[] strtemp = new String[str.countTokens()];
                                while (str.hasMoreTokens()){
                                x[n][d++] = Double.parseDouble(str.nextToken());
                                d++;
                                System.out.println(x[n][d++]);
                        stringToRead=new String();
                t[n]=Double.parseDouble(stringToRead);
                x[n][par.d()]=1.0;
        }Not sure exactly what you are trying to do above but...
You are setting your String to an empty String with "new String()" and then parsing that empty String. Eventually, you are trying to parse a double from that empty String:
t[n]=Double.parseDouble(stringToRead);Also, I cannot think of a reason to ever use "new String()" when you could just use:
String myString = "";