在Java中将INT（0-255）转换为UTF8 char

Question

since I need to control some devices, I need to send some bytes to them. I'm creating those bytes by putting some int values together (and operator), creating a byte and finally attaching it to a String to send it over the radio function to the robot.

Unfortuantely Java has some major issues doing that (unsigned int problem)

Does anybody know, how I can convert an integer eg

x = 223; 

to an 8-bit character in Java to attach it to a String ?

char = (char)x;   // does not work !! 16 bit !! I need 8 bit !

Answer 1

A char is 16-bit in Java. Use a byte if you need an 8-bit datatype.

See How to convert Strings to and from UTF8 byte arrays in Java on how to convert a byte[] to String with UTF-8 encoding.

Answer 2

Sending a java.lang.String over the wire is probably the wrong approach here, since Strings are always 16-bit (since Java was designed for globalization and stuff). If your radio library allows you to pass a byte[] instead of a String, that will allow you to send 8-bit values without needing to worry about converting to UTF8. As far as converting from an int to an unsigned byte, you'll probably want to look at this article .

Answer 3

int to array of bytes

public byte[] intToByteArray(int num){
      byte[] intBytes = new byte[4];
      intBytes[0] = (byte) (num >>> 24);
      intBytes[1] = (byte) (num >>> 16);
      intBytes[2] = (byte) (num >>> 8);
      intBytes[3] = (byte) num;
      return intBytes;
}

note endianness here is big endian.