How to add a string to a big file in csharp !

Question

I am not familiar with the stream,all help is welcome.thanx! The fallow is the java code and i want to write it in csharp ! import java.io.File; import java.io.* import java.util.Locale; import java.util.Comparator; import java.text.Collator; public class RandomAccessWordList implements WordList { /** The name of the random access word list. This name * is usually unique within a JVM. */ protected String name = null; /** The file this word list maps to. */ protected File file = null; /** The random access file object. This object is released * when there are no queries. */ protected RandomAccessFile raf = null; /** The comparator. */ protected Comparator comparator = DEFAULT_COMPARATOR; /** Reference count. It is incremented in notifyCheckStart() * method and decremented in notifyCheckEnd() method. So * we can tell the current number of queries on this word list. */ protected int inUse = 0; /** A lock used to synchonized access to the file. */ private Object lock = new Object(); /** Protected default construtor. */ protected RandomAccessWordList() { } /** Constructs a RandomAccessWordList from a File. * The name of this word list is defaultly the file name * (file.getName()). * * @param file the file to construct this word list * @throws WordListException if file is null, * or the file does not actually exists */ public RandomAccessWordList(File file) throws WordListException { if (file == null) { throw new WordListException( "file should not be null"); } if (!file.exists()) { throw new WordListException( file.getName() + " not exist."); } this.file = file; this.name = file.getName(); } /** Constructs a RandomAccessWordList from a File and * its name. * * @param file the file to construct this word list * @param name the name of this word list * @throws WordListException if file is null, * or the file does not actually exists, * or name is null or empty */ public RandomAccessWordList(File file, String name) throws WordListException { if (file == null) { throw new WordListException( "file should not be null"); } if (!file.exists()) { throw new WordListException( file.getName() + " not exist."); } if (name == null || name.length() == 0) { throw new WordListException( "name should not be null or empty."); } this.file = file; this.name = name; } /** TCSpellChecker calls this to notify that a query * finishes. RandomAccessWordList would close the * RandomAccessFile if it is there is no other queries * on this word list. */ public synchronized void notifyCheckEnd() { --inUse; if (inUse == 0) { try { raf.close(); raf = null; } catch (IOException ioe) { ; } } } /** TCSpellChecker calls this to notify that a query * is about to take place. RandomAccessWordList would * open a RandomAccessFile if it is not opened. */ public synchronized void notifyCheckStart() { if (inUse == 0) { try { raf = new RandomAccessFile(file, "r"); } catch (FileNotFoundException fnfe) { ; // should not reach here // we've checked in constructor } } ++inUse; } /** Add a word to this word list. For the fact that * the words in the word list should be ordered to * allow a binary search, the insertion of a word is * quite an expensive operation. A temporary file is * opened to help move the words. The file should be * writable for this method to succeed. * * @param word the word to be added to this word list * @throws WordNotAddedException if the word already * exists in this word list, or the file is * read-only, or other exception occurs */ public synchronized void addWord(String word) throws WordNotAddedException { if (word == null) { throw new WordNotAddedException(); } // first check whether the word exists // if does, just throw a WordNotAddedException notifyCheckStart(); try { if (findWord(word)) { notifyCheckEnd(); throw new WordNotAddedException( "Word already exists."); } } catch (WordNotAddedException wnae) { throw wnae; } catch (WordListException wle) { notifyCheckEnd(); throw new WordNotAddedException(wle.getMessage()); } notifyCheckEnd(); // if not, create a temp file and get prepared for the move File tempFile; try { tempFile = File.createTempFile("WordList", "tmp"); } catch (IOException ioe) { throw new WordNotAddedException( "IOException: Can't create temp file"); } // acquire the lock synchronized (lock) { try { // move all the words into the temp file PrintWriter pw = new PrintWriter( new BufferedWriter( new FileWriter(tempFile))); BufferedReader br = new BufferedReader( new FileReader(file)); while (br.ready()) { pw.println(br.readLine()); } pw.close(); br.close(); // move back pw = new PrintWriter( new BufferedWriter( new FileWriter(file))); br = new BufferedReader( new FileReader(tempFile)); boolean added = false; while (br.ready()) { String currentWord = br.readLine(); // this is the place where the word should be inserted if (!added && comparator.compare(word, currentWord) < 0) { pw.println(word); added = true; } pw.println(currentWord); } // oops, it becomes the last one if (!added) { pw.println(word); } pw.close(); br.close(); } catch (IOException ioe) { // still delete the temp file if something happens tempFile.delete(); throw new WordNotAddedException( "IOException: " + ioe); } } // clear up tempFile.delete(); } /** Check whether the specified word exists in this word list. * Since binary search is used, this operation is quite efficient * even for a large list file. * * @param word the word to be checked * @return whether the word exists * @throws WordListException if exception occurs */ public synchronized boolean findWord(String word) throws WordListException { if (word == null) { throw new WordListException(); } // acquire the lock synchronized (lock) { try { // check whether the first word matches raf.seek(0); String str = raf.readLine(); if (str == null) { return false; } if (comparator.compare(word, str.trim()) == 0) { return true; } // binary search starts long lower = 0; long upper = raf.length() - 1; while (lower <= upper) { long index = (lower + upper) / 2; raf.seek(index); // read off an incomplete line raf.readLine(); str = raf.readLine(); // the line might be null if it's the end of file int t = str == null ? -1 : comparator.compare(word, str.trim()); // found it ^_^ if (t == 0) { return true; } if (t > 0) { lower = index + 1; } else { upper = index - 1; } } } catch (IOException ioe) { throw new WordListException("IOException: " + ioe); } } // not found return false; } }