How do I convert byte[] to String?

Question

I've got a class that pulls information from a GPS receiver on a COM port. That works fine, but the information I'm getting from the port is in the following format:
Reading serial port...
44,44,52,46,50,44,77,44,45,51,52,46,50,44,77,44,44,48,48,48,48,42,120,30,-104,-128,96,120,96,0,-26,126,-98,-104,-98,0,30,-122,6,30,-122,6,120,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,-122,-32,120,-122,-32,-122,-32,-122,-32,-122,-104,-122,6,120,6,-98,30,-104,-128,96,120,96,0,-26,24,-26,-26,-104,30,30,-122,24,120,-32,120,30,102,120,-26,120,-26,-4,48,50,52,44,86,44,52,48,53,54,46,49,50,50,49,44,78,44,48,55,51,53,52,38,54,70,70,-58,118,-115,25,25,89,70,6,102,6,-122,-58,-58,-58,-26,83,102,-122,
-61,-31,
36,71,80,71,71,65,44,50,49,52,53,53,54,46,48,50,52,44,52,48,53,54,46,49,50,50,49,44,78,44,48,55,51,53,52,46,50,51,52,52,44,87,44,48,44,48,48,44,44,52,46,50,44,77,44,45,51,52,46,50,44,77,44,44,48,48,48,48,42,52,66,13,10,36,71,80,71,83,
65,So it's pretty obvious that it's spitting out ASCII values, so I changed the code a bit to print out the corresponding letters instead:
Reading serial port...
$GPGGA,214724.031,4056.1221,N,07354.2344,W,0,00,,4.2,M,-34.2,M,,0000*48
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,11,31,70,286,,14,57,089,,32,51,293,,30,44,061,*7D
$GPGSV,3,2,11,05,24,046,,22,23,167,,20,20,315,,16,15,194,*70
$GPGSV,3,3,11,12,12,039,,29,09,103,,11,00,279,*4F
$GPRMC,214724.031,V,4056.1221,N,07354.2344,W,,,140608,,,N*68
$GPGGA,214725.031,4056.1221,N,07354.2344,W,0,00,,4.2,M,-34.2,M,,0000*49
$GPGSA,A,1,,,,,,,,,,,,,,,*1ENow those are the NMEA sentences that the GPS receiver spits out, that's exactly what I need. Only problem is I'm printing them out using the following code:
      byte[] buffer = new byte[4096];
      InputStream theInput = thePort.getInputStream();
      System.out.println("Reading serial port...");
      while (canRead()) // Loop
        int bytesRead = theInput.read(buffer);
        if (bytesRead == -1)
          break;
        for (int z = 0; z < bytesRead; z++)
             System.out.print(Character.toString((char)buffer[z]));
        }So as you can see, it's simply taking the byte, converting it from ASCII to a symbol or letter, and putting it on the screen. Then it moves onto the next byte. So what I've tried to do is change it again so that it adds each converted letter to a string value, starting a completely new string every time it hits a $ sign, which always starts a NMEA sentence:
      byte[] buffer = new byte[4096];
      InputStream theInput = thePort.getInputStream();
      System.out.println("Reading serial port...");
      while (canRead()) // Loop
        int bytesRead = theInput.read(buffer);
        if (bytesRead == -1)
          break;
        String s = "";
        for (int z = 0; z < bytesRead; z++)
             if (Character.toString((char)buffer[z]).equalsIgnoreCase("$") && s.length() > 1)
                  System.out.println(s);
                  s = Character.toString((char)buffer[z]);
             else
                  s = s + Character.toString((char)buffer[z]);
//             System.out.print(Character.toString((char)buffer[z]));
s = "";
}The problem with this is for some reason the sentences aren't whole, there's line breaks inserted into them. So when I'm passing them to the parser, I'm passing incomplete sentences. Here's the output I'm getting now:
Reading serial port...
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
.2,M,-34.2,M,,0000*4D
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
,32,51,293,,30,44,061,*7D
$GPGSV,3,3,11,12,12,039,,29,09,103,,11,00,279,*4FHow do I get each NMEA sentence into a string so I can send it to a parser? Any ideas?
Edited by: DeX on Jun 14, 2008 6:02 PM

Answer 1

Your problem is that you're assuming a newline actually indicates the end of a line.
Assuming you can't fix the sender (or yell at the maintainer and get him to fix it), take
advantage of the fact that you know what a valid line starts with and just ignore the newline
characters.
Thanks but that gives me the same result. I think my issue is with the multithreading,
another thread is rolling through and assigning values to the String before the previous
thread is finished copying the bytes to it. I suggest you take advantage of the StringBuilder class. Also, if you insist on using the
String(byte[ ]) constructor, you should note that you're assuming a charset, a rather
dangerous thing to do. Use the String(byte[ ], String) constructor instead and explicitly use US-ASCII.