Find and Replace exact string in java

Below code will find and replace the string
import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;

public class FindReplace
{
  private static byte[] sought;
  private static byte[] replacement;
  public static String varyingSessionId = null;

  private String SessionID = null;

  private static boolean matches(MappedByteBuffer bb, int pos)
  {
    for (int j = 0; j < sought.length; j++)
    {
      if (sought[j] != bb.get(pos + j)) {
        return false;
      }
    }
    return true;
  }

  private static void replace(MappedByteBuffer bb, int pos)
  {
    for (int j = 0; j < sought.length; j++)
    {
      byte b = j < replacement.length ? replacement[j] : 32;
      bb.put(pos + j, b);
    }
  }

  private static void searchAndReplace(MappedByteBuffer bb, int sz, String fileName)
  {
    int replacementsCount = 0;

    for (int pos = 0; pos <= sz - sought.length; pos++)
    {
      if (!matches(bb, pos))
        continue;
      replace(bb, pos);

      pos += sought.length - 1;

      replacementsCount++;
    }
  }

  private static void patchSessionMethod(File f)
    throws IOException
  {
    RandomAccessFile raf = new RandomAccessFile(f, "rw");

    FileChannel fc = raf.getChannel();

    int sz = (int)fc.size();

    MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_WRITE, 0L, sz);

    searchAndReplace(bb, sz, f.getName());

    bb.force();

    raf.close();
  }

  public FindReplace(String replace)
  {
    this.SessionID = new ReadSession().getConfig("SessionId");
    System.out.println("11.0.1 ***** Inside FindReplace Constructor ***** ");
    System.out.println("11.0.1.1 ***** New Search SessionID ***** " + this.SessionID);
    System.out.println("11.0.1.2 ***** Replace SessionID ***** " + replace);
    if (this.SessionID.length() != replace.length())
      validateSessionSize();
    else {
      varyingSessionId = replace;
    }
    sought = ("session=" + this.SessionID.trim()).getBytes();

    replacement = ("session=" + replace.trim()).getBytes();

    System.out.println("***** Reading Binary Files Path ***** " + ReadProperties.getConfig("BinaryFiles"));
    File f1 = new File(ReadProperties.getConfig("BinaryFiles"));
    File[] listOfFiles = f1.listFiles();
    for (int i1 = 0; i1 < listOfFiles.length; i1++) {
      if (!listOfFiles[i1].isFile())
        continue;
      String files = listOfFiles[i1].getName();
      if ((!files.endsWith(".binary")) && (!files.endsWith(".BINARY")))
        continue;
      File f = new File(files);
      try
      {
        patchSessionMethod(f);
      }
      catch (Exception x)
      {
        System.err.println(f + ": " + x);
      }
    }
  }

  

  public static void main(String[] args)
  {
    FindReplace FRC = new FindReplace("12345");
  }
}