Tail function in JAVA. Get the last lines of a given file.


Obtaining the last lines of a large file 'efficiently':

/**
* Get the last lines of the file
**/
 public String tail(File file, int lines) {
        java.io.RandomAccessFile fileHandler = null;
        try {
            fileHandler = new java.io.RandomAccessFile(file, "r");
            long fileLength = fileHandler.length() - 1;
            StringBuilder sb = new StringBuilder();
            int line = 0;

             for (long filePointer = fileLength; filePointer != -1; filePointer--) {
                fileHandler.seek(filePointer);
                int readByte = fileHandler.readByte();

                 if (readByte == 0xA) {
                    line = line + 1;
                    if (line == lines) {
                        if (filePointer == fileLength) {
                            continue;
                        }
                        break;
                    }
                } else if (readByte == 0xD) {
                    line = line + 1;
                    if (line == lines) {
                        if (filePointer == fileLength - 1) {
                            continue;
                        }
                        break;
                    }
                }
                sb.append((char) readByte);
            }

             String lastLine = sb.reverse().toString();
            return lastLine;
        } catch (java.io.FileNotFoundException e) {
            e.printStackTrace();
            return null;
        } catch (java.io.IOException e) {
            e.printStackTrace();
            return null;
        } finally {
            if (fileHandler != null) {
                try {
                    fileHandler.close();
                } catch (IOException e) {
                }
            }
        }
    }

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