How to Convert Int to Unsigned Byte and Back

Question

I need to convert a number into an unsigned byte. The number is always less than or equal to 255, and so it will fit in one byte.

I also need to convert that byte ba

Answer 1

The solution works fine (thanks!), but if you want to avoid casting and leave the low level work to the JDK, you can use a DataOutputStream to write your int's and a DataInputStream to read them back in. They are automatically treated as unsigned bytes then:

For converting int's to binary bytes;

ByteArrayOutputStream bos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(bos);
int val = 250;
dos.write(byteVal);
...
dos.flush();

Reading them back in:

// important to use a (non-Unicode!) encoding like US_ASCII or ISO-8859-1,
// i.e., one that uses one byte per character
ByteArrayInputStream bis = new ByteArrayInputStream(
   bos.toString("ISO-8859-1").getBytes("ISO-8859-1"));
DataInputStream dis = new DataInputStream(bis);
int byteVal = dis.readUnsignedByte();

Esp. useful for handling binary data formats (e.g. flat message formats, etc.)