Java appends increment to file before

Question

I need to add an incremental number to a file that existed before, I know how to do this, and how to add a number at the end, but I need an idea how to increase the number every time

Take a look at this, for example. understand me C: \ MyFiles \ File.pdf exists, so try C: \ MyFiles \ File1.pdf and next time C: \ MyFiles \ File2.pdf

I don’t know how to get the last increment

and plz, see my code, I can only increase once

    int indexOfDot = fName.indexOf(".");
    //if theres a dot, start one character before it, otherwise,
    //start at the end of the string
    int startIndex = indexOfDot > -1 ? indexOfDot - 1 : fName.length() - 1;
    if(indexOfDot > -1)
         fileNameSuffix = fName.substring(indexOfDot, fName.length());
    //search backward on the name to see if it already
    //has a number and count the digits
    StringBuffer digits = new StringBuffer();
    char character = 0;
    for (int i = startIndex; i >= 0; i--)
    {
         character = fName.charAt(i);
         if (Character.isDigit(character))
         {
              digits.append(character);
         }
    }
    if (digits.length() > 0)
    {
          //There where already digits in the filename.
          //Create a number from the digits and add 1
          Integer newNumber =new Integer(Integer.parseInt(digits.toString()) + 1);
          //Then append that to the actual filename
          String actualFileName = fName.substring(0, startIndex + 1 - digits.length());
          rtnNewFileName = actualFileName + newNumber.toString() + fileNameSuffix;
    }else
    {
          //There where no digits in the filename
          //Append 1 to the actual filename
          String actualFileName = fName.substring(0, startIndex - digits.length());
          rtnNewFileName = actualFileName + "1" + fileNameSuffix;
   }

   file.setFileName(rtnNewFileName);

   out.println("<li>File Uploaded <br/>Form field : uploadfile"+"<BR> Uploaded file : "+file.getFileName()+" ("+file.getFileSize()+" bytes)"+"<BR> Content Type : "+file.getContentType());

    //Uses the bean now to store specified by jsp:setProperty at the top.
    upBean.store(mrequest, "uploadfile");

Answer 1

Hi everyone, I find the answer you just added (C0Py0) for each new file loaded after this test, if your file is exsite than calling the change () method;

<%! String reverseIt ( ) {   int i, len = source.length();   StringBuffer dest = new StringBuffer (len);

for (i = (len - 1); i >= 0; i--)
  dest.append(source.charAt(i));
return dest.toString();

}

% > <%! (String ffName) { String newName, ext, finalName; String invName, increment; String copyf = null; ;   int = 0;   int j = 0;   int incr;   int k = j + 4;

NEWNAME = ffName.substring(0, ffName.length() - 4); ext = ffName.substring(ffName.length() - 3, ffName.length());

  invName=reverseIt(newName);

                                while(k != invName.length()){

                                 if( invName.substring(j,k).equals("yP0C")){
                                                              copyf=invName.substring(0,j);
                                                              k=invName.length()-1;

                                                                        }
                                 else{
                                     j++;
                                     k++;
                                    }

                                                             }
increment=reverseIt(copyf);
//System.out.println(increment);
incr=Integer.parseInt(increment);
incr+=1;
newName=newName.substring(0,newName.length()-(j-1));
increment=String.valueOf(incr);
finalName=newName+increment+"."+ext;

return finalName;
}

% >

, outpers

Answer 2

File2.pdf , ,

btw :

Pattern p = Pattern.compile("(.*?)(\\d+)?(\\..*)?");
do{
    Matcher m = p.matcher(fName);
    if(m.matches()){//group 1 is the prefix, group 2 is the number, group 3 is the suffix
        fName = m.group(1) + (m.group(2)==null?1:(Integer.parseInt(m.group(2)) + 1)) + (m.group(3)==null?"":m.group(3));
    }
}while(new File(fName).exists());//repeat until a new filename is generated

Answer 3

, ( rachet)

Pattern p = Pattern.compile("(.*?)(\\d+)?(\\..*)?");

while(new File(pathname).exists()){
    Matcher m = p.matcher(pathname);
    if(m.matches()){//group 1 is the prefix, group 2 is the number, group 3 is the suffix
        pathname = m.group(1) + (m.group(2)==null?1:(Integer.parseInt(m.group(2)) + 1)) + (m.group(3)==null?"":m.group(3));
    }
}