Question

I’m having a strange problem comparing strings. I send a string to my server (as bytes using getBytes()) from the client. I’ve ensured that encoding is the same on the client and server by starting both of them with -Dfile.encoding=UTF-8.

I noticed the problem when I was trying to perform a valueOf on the string I receive from the client, to convert it into an enum. When I print out the strings, they look exactly the same. But when I perform a compareTo, I get a non-zero number and equals returns false.

I’m assuming that it is an encoding problem. I’m not really sure though — I’m still a bit of a novice when it comes to client-server programming with sockets.

This is what I get:

Waiting for connections on port 9090
Connected to client: 127.0.0.1
received command: GetAllItems
The value is |GetAllItems| (from client)
The value is |GetAllItems| (from enum)
equals: false

What am I doing wrong?

UPDATE

Here is how I’m reconstituting the string from the stream. Perhaps this is where I’m doing something wrong?

byte[] commandBytes = new byte[1024];
in.read(commandBytes); //in is a BufferedInputReader
String command = new String(commandBytes);

Answer 1

My guess is that since your buffer is bigger than your string, there are added nulls in the reconsituted string. It is legal for nulls to be embedded inside strings in Java (unlike C and company), although Java handles them differently than standard UTF-8.

Try recording the length read, and pass that length to the string constructor:

int bytesRead = in.read(commandBytes);
String command = new String(commandBytes, 0, bytesRead);