Open/edit file

Question

I need to open a file, and edit part of the file based on some static text in that file. For example, lets say the text file looks something like this:
a
b
c
1
2
1
a
b
c
I need a program that will open the file, and delete everything from the first 1 to the last 1, and do nothing if no 1's exist.
Afterwards, save the existing file.
Can someone please show me how to do this?
Thanks.

Answer 1

I finished writing the program I was asking about. In case anyone needs anything like this in the future, I have posted the program here(w/ a few modifications):
import java.io.IOException;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.File;
import java.util.Collection;
import java.util.ArrayList;
public class ABC{
   // Main method
   public static void main(String args[]) {
      // Stream to read file
      FileReader fr;
      FileWriter fw;
      Collection<String> lineStorage = new ArrayList<String>();
      String line = "";
      boolean finishedRemoving = true;
      final String filePath = "b.xml";
      try {
         // Open an input stream
         fr = new FileReader(filePath);
         // Read a line of text
         BufferedReader br = new BufferedReader(fr);
         while (br.ready()) { //while there's another line
            line = br.readLine();
            if (line.compareToIgnoreCase("  <app>") == 0) {
               finishedRemoving = false;
               continue;
            } else if (line.compareToIgnoreCase("  </app>") == 0) {
               finishedRemoving = true;
               continue;
            if (finishedRemoving) {
               lineStorage.add(line);
         // Close our input stream
         fr.close();
         fw = new FileWriter(filePath);
         BufferedWriter bw = new BufferedWriter(fw);
         for (String aLineStorage : lineStorage) {
            bw.write(aLineStorage);
            bw.newLine();
         bw.flush();
         fw.close();
      // Catches any error conditions
      catch (IOException e) {
         System.err.println("Unable to read from file");
         System.exit(-1);
}