Byte[ ] and String

Question

I am reading data into a byte array which i declare to be of size (lets say 40). the data that i read varies between lets say 30-40(but i still delare the byte array to be of size 40 so that it has enough space to handle cases from 30-40). The problem is that I need to create a string with this data...and i do so using
String data = new String (byteArray[);               //where byteArray holds data that i read
but for some reason when i try to print data...it prints the character [][][][]][][] for the unused portion of the byte array.
for example if my data is 123456789......................30.
and i read it into a byte array of size 40
and then convert to string and try to print it wil print 123456789................30[][][][][][][][][] .
how can i solve this problem?

Answer 1

heres some code of what im trying to do, if you dont understand datagrams you can just ignore those specifis
public String recieveCommand(){
byte[] data = new byte[40];
try{
packet=new DatagramPacket(data,40);
socket.receive(packet);
}catch(Exception e){System.out.println(e.toString());}
String command=new String( packet.getData() );