files are empty when writing multiple files

Question

I'm trying to read one file and write several files after modifying a small point.

My code works while writing the first file, but the other files are empty files. :(

I think there is a problem when I use bufferedwriter and filewriter, but can't find what the problem is though I followed an advice to use flush from stackoverflow.

What is the problem in my code?

        FileReader fr = new FileReader(FileDir);
        BufferedReader br = new BufferedReader(fr);
        for (String mc: matchedContents){
            FileWriter fw = new FileWriter(saveFileDir+String.valueOf(matchedContents.indexOf(mc)+1)+".xml", false);
            BufferedWriter bw = new BufferedWriter(fw);
            while ((s = br.readLine())!=null){
                // check if s has matched contents
                if (s.contains(mc)){
                    String replacedString="";
                    if (mc.contains("NV"))
                        replacedString = s.replace(mc, "NV("+anyItem(edgeNames)+")");
                    else if (mc.contains("AW"))
                        replacedString = s.replace(mc, "AW("+anyItem(edgeNames)+")");
                    bw.write(replacedString);
                    bw.newLine();
                }
                else {
                    bw.write(s);
                    bw.newLine();
                }
            }
            System.out.println(mc+" end");
            bw.flush();
            bw.close();
            fw.close();
        }
        br.close();
        fr.close();

try and use that magically thing called a debugger.

Scary Wombat
– Scary Wombat

2016-09-01 05:57:12 +00:00
Commented Sep 1, 2016 at 5:57 — Scary Wombat
– Scary Wombat, Commented Sep 1, 2016 at 5:57

Anoop LL · Accepted Answer · 2016-09-01 06:06:38Z

2

Its because after the first file your bufferedReader comes to the end. To write again you need to reload the file to bufferedReader. So what you need to do is make the bufferedReader and the FileReader inside the for loop

    for (String mc: matchedContents){
        FileReader fr = new FileReader(FileDir);
        BufferedReader br = new BufferedReader(fr);
        FileWriter fw = new FileWriter(saveFileDir+String.valueOf(matchedContents.indexOf(mc)+1)+".xml", false);
        BufferedWriter bw = new BufferedWriter(fw);
        while ((s = br.readLine())!=null){
            // check if s has matched contents
            if (s.contains(mc)){
                String replacedString="";
                if (mc.contains("NV"))
                    replacedString = s.replace(mc, "NV("+anyItem(edgeNames)+")");
                else if (mc.contains("AW"))
                    replacedString = s.replace(mc, "AW("+anyItem(edgeNames)+")");
                bw.write(replacedString);
                bw.newLine();
            }
            else {
                bw.write(s);
                bw.newLine();
            }
        }
        System.out.println(mc+" end");
        bw.flush();
        bw.close();
        fw.close();
        br.close();
    }

    fr.close();

edited Sep 1, 2016 at 6:06

answered Sep 1, 2016 at 6:01

Anoop LL

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1 Comment

cointreau Over a year ago

Thanks!! but FileReader fr = new FileReader(FileDir); should be in for loop too.. or, it does not work.

Community · Accepted Answer · 2017-05-23 12:22:50Z

0

I would try debugging the code line by line and check what is exactly being written to the second, third etc. file (maybe the file writing is OK, but empty strings are being written?).

Also check:
Debugging Java code line by line
Java read in single file and write out multiple files

edited May 23, 2017 at 12:22

CommunityBot

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answered Sep 1, 2016 at 6:04

Fr333du

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