CODEWITHSUNDEEP
javaunsignedshort
gansub
gansub

Reputation: 1174

Getting signed short values when I wanted to write out unsigned short values

Using the solution provided here -Java input and output binary file byte size are not matching after transformation I wrote out a 2-dimensional array to disk that consists of unsigned shorts. When I checked the values of this file by reading them in I still see signed values i.e. negative values. What is the error in the code ?

fos = new FileOutputStream(destFile);
short[][] data = getData(); //defined in another class
if (ByteOrder.nativeOrder().equals(ByteOrder.BIG_ENDIAN)
 {
   for (int i = 0;i<1200;i++)
    {
      for (int j = 0; j <1200;j++)
        {      
          fos.write((data[i][j] >> 8) & 0xFF);
          fos.write(data[i][j] & 0xFF);
        }
    }
 }
 else
     {
       for (int i = 0;i<1200;i++)
         {
          for (int j = 0; j <1200;j++)
           {
             fos.write(data[i][j] & 0xFF);
             fos.write((data[i][j] >> 8) & 0xFF);

            }
         }     
     }

Upvotes: 2

Views: 240

Answers (1)

Joni
Joni

Reputation: 111259

Java doesn't have an unsigned short datatype, but don't worry, the code works fine. The bit patterns for signed and unsigned are the same, the difference is in how the first bit is interpreted. If you ever want the unsigned value for a short you can use the AND operator:

int unsignedValue = signedShortValue & 0xFFFF;

Upvotes: 1

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