Search a string in a file and write the matched lines to another file in Java
file-io, java
Solution
You are reopening the file output handle for every single line you write.
This is likely to have a massive performance impact, far outweighing other performance issues. Instead I would recommend creating the `BufferedWriter` once (e.g. upon the first match) and then keeping it open, writing each matching line and then closing the `Writer` upon completion.
Also, remove the call to `flush()`; there is no need to flush each line as the call to `Writer.close()` will automatically flush any unwritten data to disk.
Finally, as a side note your variable and method naming style does not follow the Java camel case convention; you might want to consider changing it.
Problem
For searching a string in a file and writing the lines with matched string to another file it takes 15 - 20 mins for a single zip file of 70MB(compressed state). Is there any ways to minimise it. my source code: getting Zip file entries ``` zipFile = new ZipFile(source_file_name); entries = zipFile.entries(); while (entries.hasMoreElements()) { ZipEntry entry = (ZipEntry)entries.nextElement(); if (entry.isDirectory()) { continue; } searchString(Thread.currentThread(),entry.getName(), new BufferedInputStream (zipFile.getInputStream(entry)), Out_File, search_string, stats); } zipFile.close(); ``` Searching String ``` public void searchString(Thread CThread, String Source_File, BufferedInputStream in, File outfile, String search, String stats) throws IOException { int count = 0; int countw = 0; int countl = 0; String s; String[] str; BufferedReader br2 = new BufferedReader(new InputStreamReader(in)); System.out.println(CThread.currentThread()); while ((s = br2.readLine()) != null) { str = s.split(search); count = str.length - 1; countw += count; //word count if (s.contains(search)) { countl++; //line count WriteFile(CThread,s, outfile.toString(), search); } } br2.close(); in.close(); } -------------------------------------------------------------------------------- public void WriteFile(Thread CThread,String line, String out, String search) throws IOException { BufferedWriter bufferedWriter = null; System.out.println("writre thread"+CThread.currentThread()); bufferedWriter = new BufferedWriter(new FileWriter(out, true)); bufferedWriter.write(line); bufferedWriter.newLine(); bufferedWriter.flush(); } ``` Please help me. Its really taking 40 mins for 10 files using threads and 15 - 20 mins for a single file of 70MB after being compressed. Any ways to minimise the time.