concat - is there a bug in java new String -

i try code:

byte[] data = new byte[66000]; int count = is.read(data); string srequest = new string(data);  //will received byte array hello string = srequest;         = all.concat("world"); system.out.println(all); 

it print console: hello

concat funtion of java have bug? used + operator instead concat function result same :( how can concat string new string byte array?

instead of

    string srequest = new string(data);  //will received byte array hello 

use

    string srequest = new string(data, 0, count);  //will received byte array hello 

you notice difference when additionally print length of result string:

    system.err.println(all + "/" + all.length()); 

gives helloworld/66005 in first case , helloworld/10 in second case. reason see "hello" might issue of console - in eclipse, see "helloworld" when copy&paste editor 1 of words taken. 0 values initial array part of result (since had been added first string), not printed out (since not printable characters).