CODEWITHSUNDEEP
javaeclipsefilejava.util.scannerwriter
user2598911
user2598911

Reputation: 379

Replacing some lines in a file

I have a file that my scanner reads, then in a new file my writer copies some part of it, and replaces the lines I want to edit.

I have a problem in some specific lines, to which I want to add some elements from a stringarray [Ddd,Eee,...].

My problem is that I can't get the scanner and the filewriter to identify the exact position I want to transfer the elements. They need to be below "downstream_rm", between / and / , and also they need to replace the old text.

Example/Target:

Old file lines:

 ....
    downstream_rm(j,l) ...
                / Aaa.(bbb)
                    Bbb.(ccc)  /
    ....

New file lines:

 ...
    downstream_rm(j,l( ....
         / str1 
             str2
               ... /

This code I tried, but didnt get the desired results cause it also keeps the old text:

public static void main(String[] args) {

File file = new File();
File filenew = new File();

        try {


                    PrintWriter out = new PrintWriter(new FileWriter(filenew, true));
                    Scanner scanner = new Scanner(file);




                           while (scanner.hasNextLine()) {
                               String line = scanner.nextLine();


        if(line.contains("downstream_rm(j,l)")) {

                                           scanner.nextLine();   // so that the line with "downstream" wont be deleted

                                           String raw = "" ;


                                           for (int index = 0; index < strarray.size(); index++) {

                                                  String s = strarray.get(index);
                                                   raw = raw + "\n" + s;
                                               }

                                        line = "/"+raw+"/" ; } 
             out.write(line);
        out.write("\n");

                         }
                       out.flush();
                       out.close();
                       scanner.close();


            } catch (IOException e)  {
                e.printStackTrace();


            }
          }
    }

Also tried this, but it didnt print anything new:

        if(line.contains("downstream_rm(j,l)")){

                               scanner.nextLine();

                               String raw = "" ;


                               for (int index = 0; index < strarray.size(); index++) {

                                      String s = strarray.get(index);
                                       raw = raw + "\n" + s;
                                   }

                        String raw2 = raw.replaceAll(",", "");

                               line = line.replaceAll("/.*?/", "/"+raw2+"/");
                               }  
    out.write(line);
out.write("\n");

Upvotes: 0

Views: 122

Answers (1)

Eugen Halca
Eugen Halca

Reputation: 1785

your code is not doing what it should because in line

 line = line.replaceAll("/.*?/", "/"+raw2+"/");

string from reference "line" doesn't match regex, therefore it doesn't replace

here is what your need 

if (line.contains("downstream_rm(j,l)")) {
            String replacement = line;
            while (!replacement.matches(".*?/.*?/.*?")) {
                replacement += scanner.nextLine();
            }
            String raw = "";
            for (int index = 0; index < strarray.size(); index++) {

                String s = strarray.get(index);
                raw = raw + "\n" + s;
            }
            String raw2 = raw.replaceAll(",", "");
            line = replacement.replaceAll("/.*?/", "/" + raw2 + "/");
        }

just make sure your "raw2" variable points to right String object, and in result variable line will contain replaced string

Upvotes: 2

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