Converting 32-bit unsigned integer (big endian) to long and back
-
26-05-2021 - |
Question
I have a byte[4] which contains a 32-bit unsigned integer (in big endian order) and I need to convert it to long (as int can't hold an unsigned number).
Also, how do I do it vice-versa (i.e. from long that contains a 32-bit unsigned integer to byte[4])?
Solution
Sounds like a work for the ByteBuffer.
Somewhat like
public static void main(String[] args) {
byte[] payload = toArray(-1991249);
int number = fromArray(payload);
System.out.println(number);
}
public static int fromArray(byte[] payload){
ByteBuffer buffer = ByteBuffer.wrap(payload);
buffer.order(ByteOrder.BIG_ENDIAN);
return buffer.getInt();
}
public static byte[] toArray(int value){
ByteBuffer buffer = ByteBuffer.allocate(4);
buffer.order(ByteOrder.BIG_ENDIAN);
buffer.putInt(value);
buffer.flip();
return buffer.array();
}
OTHER TIPS
You can use ByteBuffer, or you can do it the old-fashioned way:
long result = 0x00FF & byteData[0];
result <<= 8;
result += 0x00FF & byteData[1];
result <<= 8;
result += 0x00FF & byteData[2];
result <<= 8;
result += 0x00FF & byteData[3];
Guava has useful classes for dealing with unsigned numeric values.
Licensed under: CC-BY-SA with attribution
Not affiliated with StackOverflow