Format the number in java

[Sanny kumar]

Hi Guys,
I m writing a java program to get the sequence of number if the from no and to num is given

example
if i give from 1 to 10
the o/p is:
1
2
3
4
5
6
7
8
9
10
this works fine but whn i enter 0001 to 0010
the o/p is same as of the above.
bt i wan to display the value as follows:
0001
0002
0003
0004
0005
0006
0007
0008
0009
0010
The sample program as follows:
import java.io.*;

public class Generator{

public static void main(String args[])
{
long arg1=Long.parseLong(args[0]);
long arg2=Long.parseLong(args[1]);


try {
BufferedWriter out = new BufferedWriter(new FileWriter("generate.csv"));
for(long i=arg1;i<=arg2;i++){

out.write("\""+i+"\"");
out.write("\r\n");
}
out.close();
} catch (IOException e) {
}



}
}

any suggestions?

Thanks in advance
Santhosh

[Rahul Bhattacharjee]

You can take the length of the string argument in a integer.
Then just before outputting the value you left pad the result with zeros upto the length of the argument.

[Manio Manegra]

Hello Sanny,
the following code should solve your problem.
Please, take a look at the comments in the code for
a short explanation.

 
  public static void main(String[] args) throws IOException
  {
 
    // I find out the total lenght of the string 
    // I suppose both string have the same length 
   int totalLength = args[0].length();
   
   // this is the filler char
    final String ZERO = "0";
    
    // it represents the number of times you have to 
    // insert the filler chars before the real number
    int zeroes = 0;
    
    long arg1=Long.parseLong(args[0]);
    long arg2=Long.parseLong(args[1]);
    BufferedWriter out = null;
 
    try {
    out = new BufferedWriter(new FileWriter("generate.csv"));
    for(long i=arg1;i<=arg2;i++){
      
      // how many zeroes (filling chars) I have to 
      // insert?
      zeroes = totalLength - ("" + i).length();
      out.write("\"");
      
      // here is where I put the zeroes in
      for (int j = 1; j <= zeroes; j++)
      {
        out.write(ZERO);
      }
      out.write(i+"\"");
      out.write("\r\n");
      }
 
      } catch (IOException e) {
      } finally { 
        // this has nothing to do with your problem but
        // I think you'll be safer if you always put you
        // buffer closure inside a finally block
        if (out != null) 
          out.close();
      }
    }
    

HTH

Bye
Manio

[Rahul Bhattacharjee]

Considering reusability into account you can use a utility method available with StringUtils class with commons-lang-2.0.jar for padding the output to the length of the input string with zero.

[Jesper de Jong]

The solution is much simpler than what the others have posted. You just have to change one line. Look at the following line:

out.write("\""+i+"\"");

Modify it to this:

out.write("\"" + String.format("%04d", i) + "\"");

Works if you're using Java 5.0 or newer.

[Manio Manegra]

Jesper, your solution is short and effective, really cool! You enhanced my learning process, thank you.

Sanny, if you want apply this pattern to different padded parameters without the need to change the code you could compose the pattern used to feed String format method at runtime like this:

out.write("\"" + String.format("%0"+ totalLength + "d", i) + "\"");

where totalLenght refers to the first param length (as in the previous posted code)

int totalLength = args[0].length();

in this way if you have these arguments:

 0001 0010

you should see this output

"0001"
       "0002"
       "0003"
       ...
       "0010"

but, if you change the arguments in:

000001 000010

the output change accordingly (thanks to the run time pattern adjustment):

 "000001"
       "000002"
       "000003"
       ...
       "000010" 

Bye,
Manio