Increment numbers in XML files

Question

My code is
public class Main
    private static File fileTmp;
    private static BufferedReader br;
    private static BufferedWriter bw;
    private static String line;
    /** Creates a new instance of Main */
    public Main()
    public static void main(String args[])
        File xmlFile = new File(args[0]);
        File parentPath=new File(xmlFile.getParent(),"files");
        File [] files = parentPath.listFiles();
        for(int i=0;i<files.length;i++)
            File f = new File(files.getAbsolutePath());               
if(!(f.isDirectory()))
try
fileTmp = File.createTempFile(f.getName(), "tmp");           
br = new BufferedReader(new FileReader(f));
bw = new BufferedWriter(new FileWriter(fileTmp));
while((line = br.readLine()) != null)
if(line.contains("<citation citation-type=\"book\" id=\"\">"))
line = FunctionToIncrement(line);
bw.write(line);
bw.newLine();
catch(NullPointerException n)
n.printStackTrace();
catch(IOException ioe)
System.out.println("IOException.."+ioe.getMessage());
finally
try
br.close();
catch(Exception e)
try
bw.close();
catch(Exception e)
if(f.delete())
fileTmp.renameTo(f);
private static String FunctionToIncrement(String line)
String res = "";
int num=1;
     res = line.replace("<citation citation-type=\"book\" id=\"\">","<citation citation-type=\"book\" id=\""+num+"\">");          
System.out.println("res:"+res);
num++;
return res;
Input XML files are
XML file 1
<citation citation-type="book" id="">
<citation citation-type="book" id="">
<citation citation-type="book" id="">
<citation citation-type="book" id="">
XML file 2
<citation citation-type="book" id="">
<citation citation-type="book" id="">
XML file 3
<citation citation-type="book" id="">
From the code my Output XML files contain
XML file 1
<citation citation-type="book" id="1">
<citation citation-type="book" id="1">
<citation citation-type="book" id="1">
<citation citation-type="book" id="1">
XML file 2
<citation citation-type="book" id="1">
<citation citation-type="book" id="1">
XML file 3
<citation citation-type="book" id="1">
But Ouput XML files should contain incremented numbers as
XML file 1
<citation citation-type="book" id="1">
<citation citation-type="book" id="2">
<citation citation-type="book" id="3">
<citation citation-type="book" id="4">
XML file 2
<citation citation-type="book" id="1">
<citation citation-type="book" id="2">
XML file 3
<citation citation-type="book" id="3">Could anyone please help me to update my code.

Answer 1

int cntr=1;   // everytime the for loops goes around, we create cntr = 1
fileTmp = File.createTempFile(f.getName(), "tmp");                          
br = new BufferedReader(new FileReader(f));
bw = new BufferedWriter(new FileWriter(fileTmp));
while((line = br.readLine()) != null)
  if(line.contains("><citation citation-type=\"book\" id=\"\">"))
       line = FunctionToIncrement(line, cntr);
       cntr++;
  bw.write(line);
  bw.newLine();
private static String FunctionToIncrement(String line, int cntr)
        String res = "";
     res = line.replace("<citation citation-type=\"book\" id=\"\">","<citation citation-type=\"book\" id=\""+cntr+"\">");          
        System.out.println("res:"+res);
        return res;
} Or simply make cntr variable global to the class.
Another way to think about it this:
Your approach is fine because you are doing the increments and writing on the fly. If your XML was bigger, it wouldn't be all that great.
Count the number of instances that line occurs (DOM or SAX). Then you already know how much you need to increment. You can then write a function to take that node tree and run it in a loop to do the increment. This way there would be no need for a global counter variable, or passing a counter in.