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    <p>I had the same problem as described here. I want to look at lines in file in reverse order, from the end back to the start (The unix tac command will do it). </p> <p>However my input files are fairly large so reading the whole file into memory, as in the other examples was not really a workable option for me.</p> <p>Below is the class I came up with, it does use <code>RandomAccessFile</code>, but does not need any buffers, since it just retains pointers to the file itself, and works with the standard <code>InputStream</code> methods. </p> <p>It works for my cases, and empty files and a few other things I've tried. Now I don't have Unicode characters or anything fancy, but as long as the lines are delimited by LF, and even if they have a LF + CR it should work.</p> <p>Basic Usage is : </p> <pre><code>in = new BufferedReader (new InputStreamReader (new ReverseLineInputStream(file))); while(true) { String line = in.readLine(); if (line == null) { break; } System.out.println("X:" + line); } </code></pre> <p>Here is the main source: </p> <pre><code>package www.kosoft.util; import java.io.BufferedReader; import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.RandomAccessFile; public class ReverseLineInputStream extends InputStream { RandomAccessFile in; long currentLineStart = -1; long currentLineEnd = -1; long currentPos = -1; long lastPosInFile = -1; public ReverseLineInputStream(File file) throws FileNotFoundException { in = new RandomAccessFile(file, "r"); currentLineStart = file.length(); currentLineEnd = file.length(); lastPosInFile = file.length() -1; currentPos = currentLineEnd; } public void findPrevLine() throws IOException { currentLineEnd = currentLineStart; // There are no more lines, since we are at the beginning of the file and no lines. if (currentLineEnd == 0) { currentLineEnd = -1; currentLineStart = -1; currentPos = -1; return; } long filePointer = currentLineStart -1; while ( true) { filePointer--; // we are at start of file so this is the first line in the file. if (filePointer &lt; 0) { break; } in.seek(filePointer); int readByte = in.readByte(); // We ignore last LF in file. search back to find the previous LF. if (readByte == 0xA &amp;&amp; filePointer != lastPosInFile ) { break; } } // we want to start at pointer +1 so we are after the LF we found or at 0 the start of the file. currentLineStart = filePointer + 1; currentPos = currentLineStart; } public int read() throws IOException { if (currentPos &lt; currentLineEnd ) { in.seek(currentPos++); int readByte = in.readByte(); return readByte; } else if (currentPos &lt; 0) { return -1; } else { findPrevLine(); return read(); } } } </code></pre>
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    1. POHow to read file from end to start (in reverse order) in Java?
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    1. USMark O'Donohue
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