How can i get program to wait until file is loaded?

Question

Hi all,
I keep getting a null pointer exception error thrown when it shouldn't. I'm 99% certain that its being generated because the program speed is faster than the load file time. Is there any way to make the program wait until the file is finished loading? I know you can set up a for loop that will take up some time but I wanted it to be more accurate so that no errors will occur on any machine. Here is the code
RunMainProg();
          String[] TempHolder = new String[HowMany*2];
          try
              BufferedReader readerOne = new BufferedReader(new FileReader("TempMDLFile.txt")); // file just save from RunMainProg()
              String lineOne;
              int i=0;
                   while ((lineOne = readerOne.readLine()) != null)
                        if(i>=TempHolder.length)
                        break;
                         TempHolder=lineOne;
                         i++;
          readerOne.close();
               catch (IOException f)
                    MakeDialog ErrorDialog = new MakeDialog(TopWindow, "Load Error", "Error - The file you entered does not exist", "Error", "OK", "OK", 0, 0);
               for(int i=0; i<TempHolder.length; i++)
                    if(TempHolder[i] == null)
                    i=0;
               FormatData TestSequences = new FormatData(TempHolder); // problem occurs at this line
I have looked all over and can't seem to find a way to verify if the file is loaded, or to get it to wait until it has. Any help would be much appreciated. Especially if you can supply some code snippets :)
Much obliged
Drb2k2

Answer 1

okay, I added some test code that I was using to try and iron out the problem. Perhaps its best if I run through what happens.
1. I get the data from the text box, and an external program is run which generates some text files. These files are then loaded and examined and some new data is appended to the old. This is the process
FormatData TestSequences = new FormatData(TempHolder); Now every time its run first time around its fine.
2. When I try and do exactly the same thing with the new appended set of data the null exception is thrown. Now Dr Clap, I thought exactly the same as you did, but... If i add the following bit of code before the FormatData call..
for(int i=0; i<TempHolder.length; i++)
System.out.println(TempHolder);
It will produce the data without the appended info, and some null sequences.
The size of TempHolder is adjusted depending on the amount of data submitted, so somewhere along the line its just not working.
3. Now for the fun part, eventually if you put the call in a loop it will correct itself and produce the outcome, but needless to say i'd rather not have my program catching a load of nullpointerException errors.
Finally as for the code
for(int i=0; i<TempHolder.length; i++)               {                    if(TempHolder[i] == null)                    i=0;               }That was an attempt to stall the program until no null sequences were found. Sort of getting around the problem in 3.
Dr Clap is a legend on these posts and his advice is well recieved but I have no idea how to view a stack trace or what benefit it has. Any tips on this would be great.
Thanks for your help so far
drb2k2