Simple BufferedWriter/FileWriter error

Question

This code is driving me nuts. I can read files without a problem, but I can't seem to write anything for the life of me. I've tested the ArrayList passed to the constructor and it works fine. For my sake, assume that's not the problem. The global variables save and admin are accessed through other classes, they're meant to be public. Can anyone please proofread the code and see where I screwed up? :(
import java.io.*;
import java.util.*;
public class LifeDataThread extends Thread {
     private ArrayList<LifePlayer> players;
     private String fileName;
     public boolean save = true;
     public boolean admin = false;
     private final String file = "data.bak";
    public LifeDataThread(ArrayList<LifePlayer> list, String fn) {
         players = list;
         fileName = fn;
    @Override
    public void run() {
         try {
              while (save) {
                   if (admin == true) save = false;
                   else Thread.sleep(1000*60*5);
                   System.out.println("SAVING DATA.");
                   BufferedWriter bw = new BufferedWriter(new FileWriter(file));
                   BufferedReader br = new BufferedReader(new FileReader(file));
                   bw.write("" + players.size() + 1);
                  for (int x = 0; x < players.size(); x++) {
                       LifePlayer temp = players.get(x);
                       bw.write(temp.toString());
                       System.out.println(br.readLine());
                  File f = new File(fileName);
                  System.out.println("Delete " + fileName + ": " + f.delete());
                  f = new File(file);
                  System.out.println("Create " + file + ": done");
                  System.out.println("Rename " + file + " to " + fileName + ": " + f.renameTo(new File(fileName)));
                  bw.close();
                  br.close();
         catch (IOException e) {
              e.printStackTrace();
         catch (InterruptedException e) {
              System.err.println(e);
    }output:
SAVING DATA.
null
null //4 players
null
null
Delete data.dat: true
Create data.bak: done
Rename data.bak to data.dat: done

Answer 1

This is pretty bizarre. You're trying to read a line from a file when you never write lines to the file, and you also seem to be expecting a write to show up immediately as something that can be read, which doesn't take any account of the various buffers you have installed in teh writing chain.
If you want to test whether the file has been written, test its size after you've closed it. Or read it after you've stopped writing it and have closed the output writer.