You should not use DataOutputStream.writeUTF, see API
First, two bytes are written to the output stream as if by the writeShort method giving the number of bytes to follow. This value is the number of bytes actually written out, not the length of the string. Following the length, each character of the string is output, in sequence, using the modified UTF-8 encoding for the character. If no exception is thrown, the counter written is incremented by the total number of bytes written to the output stream. This will be at least two plus the length of str, and at most two plus thrice the length of str.
That is, what DataOutputStream.writeUTF writes can be read only with DataInputStream.readUTF
I suggest to use
OutputStreamWriter w = new OutputStreamWriter(connection.getOuputStream(), "UTF-8");
w.write(urlParameters);
w.flush();