Out of memory error when writing large file

Question

I have the piece of code below which works fine for writing small files, but when it encounters much larger files (>80M), the jvm throws an out of memory error.
I believe it has something to do with the Stream classes. If I were to replace my PrintStream reference with the System.out object (which is commented out below), then it runs fine.
Anyone else encountered this before?
     print = new PrintStream(new FileOutputStream(new File(a_persistDir, getCacheFilename()),
                                                            false));
//      print = System.out;
          for(Iterator strings = m_lookupTable.keySet().iterator(); strings.hasNext(); ) {
               StringBuffer sb = new StringBuffer();
               String string = (String) strings.next();
               String id = string;
               sb.append(string).append(KEY_VALUE_SEPARATOR);
               Collection ids = (Collection) m_lookupTable.get(id);
               for(Iterator idsIter = ids.iterator(); idsIter.hasNext();) {
                    IBlockingResult blockingResult = (IBlockingResult) idsIter.next();
                    sb.append(blockingResult.getId()).append(VALUE_SEPARATOR);
               print.println(sb.toString());
               print.flush();
} catch (IOException e) {
} finally {
     if( print != null )
          print.close();
}

Answer 1

Yes, my first code would just print the strings as I got them. But it was running out of memory then as well. I thought of constructing a StringBuffer first because I was afraid that the PrintStream wasn't allocating the memory correctly.
I've also tried flushing the PrintStream after every line is written but I still run into trouble.