Re: Number format exception

Nigel Wade <>
Wed, 09 Mar 2011 09:35:11 +0000
On 08/03/11 17:15, Venki wrote:

Can any one pls fix dis runtime error

Your code compiles fine, and works if you give it correct information.

You need to fix your input file so it contains text which your parser
can parse, or fix your parser so it can parse the input text you are
giving it. Since we don't know which is correct we can't fix it.

/* Dealing with binary data:
Create a program to read a list of floating point numbers in a text
file and then write the data to a binary file.
 (Use classes: FileReader, FileBufferedReader, FileOutputStream,
String, Float, DataOutputStream).
Use FileReader and FileBufferedReader classes to be able to read each
line of the file as a string. Use split method of String class to
break the line into words.

Your code doesn't match this instruction.

In homework, assignments, and exams make sure you answer the question
which is asked, you probably won't get any credit for being inventive.
If it was a requirement in a specification your code would have failed
to meet it.

Use Float.parseFloat to convert the string to floating point number.
Use FileOutputStream and DataOutputStream to write the float data as a
binary data to the file.

import java.util.regex.*;

public class readfloat {

Whilst you are learning Java you really ought to acquaint yourself with
the conventions, so that you don't get into bad habits which need later
correction. Class names should begin with an uppercase letter. Use camel
case - ReadFloat, if you really want to call it by that name.

  public static void main(String args[]) throws IOException {

    FileReader fr = new FileReader("input.txt");

Don't use tabs in usenet posts, it makes them difficult to read, even
more so when replies have indented them even further and caused them to

     BufferedReader br = new BufferedReader(fr);
    String s;

    Pattern pat = Pattern.compile(", ");

RE are tricky beasts. A string of characters used in an RE will match in
its entirety, it is not a sequence of single RE matched individually.
The sequence is "AND"d, not "OR"d, in that it must match all the
characters exactly in the order specified, not one or the other. To
match one of a set use "[]" to create a simple class pattern.
See the Character Classes section of the Pattern API in the Javadocs:

     FileOutputStream fout = new FileOutputStream("output.txt");

This is not a good name for a binary file...

     DataOutputStream out = new DataOutputStream(fout);
    while((s = br.readLine())!=null) {
        String str[] = pat.split(s);

Your pattern ", " matches /exactly/ ", ", the string will be split on
the two-character separator ", ". Nothing else.

Split will also create empty fields if there are consecutive separators,
so you need to deal with that.

         for(int i=0;i<str.length;i++){
            float f = Float.parseFloat(str[i]);

far too much indentation for usenet, because of the tabs.


Nigel Wade

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