Java writing out bytes from one file, reading back in again

Question

Hi, I'm having some trouble with bytes.
I have one program which outputs the following bytes into a file (using Printstream.write() - I'm sure that this program is working fine):
4 0 64 0 4 0 128 0 63 223 64 20 4 16 130 0 60 16 64 1 63 223 79 236 64 16 195 232 116 63 255 232 148 0 0 0
I'm then reading in the bytes using the code given on this page (http://www.exampledepot.com/egs/java.io/File2ByteArray.html)
and I get...
4 0 64 0 4 0 -128 0 63 -33 64 20 4 16 -126 0 60 16 64 1 63 -33 79 -20 64 16 -61 -24 116 63 -1 -24 -108 0 0 0
As you can see I now have negative numbers - I noticed that if I do 256 + (the negative number) then i get the number I originally wrote out
I tried fixing this when I read in by doing
bytes[i] = (byte) (256 + bytes);
but it doesn't change anything
how can I either change it so it reads in the bytes exactly as i wrote them out, or write a bit of code that takes the negatives and converts them to the original positives?
thx

Answer 1

Unconditional wrote:
Integer x1 = (bytes[i] << 24) & 0xFF;
                  Integer x2 = (bytes[i+1] << 16) & 0xFF;
                  Integer x3 = (bytes[i+2] << 8) & 0xFF;
                  Integer x4 = (bytes[i+3] << 0) & 0xFF;is what I'm doing
System.out.println("x1 " + x1 + " x2 " + x2 + " x3 " + x3 + " x4 " + x4);
returns
x1 0 x2 0 x3 0 x4 0
x1 0 x2 0 x3 0 x4 4
x1 0 x2 0 x3 0 x4 0
x1 0 x2 0 x3 0 x4 128
x1 0 x2 0 x3 0 x4 0
x1 0 x2 0 x3 0 x4 63
x1 0 x2 0 x3 0 x4 223
x1 0 x2 0 x3 0 x4 64
x1 0 x2 0 x3 0 x4 20What are you trying to do? Combine the bytes into an int?