Exception in thread "Thead-0" java.lang.NullPointerException at clientThread.run<Server.java:123>
There is a variable with a null value on line 123. Look at line 123 in the your source and see what variable is null. Then backtrack in the code to see why that variable does not have a valid value.
If you can not tell which variable it is, add a println just before line 123 and print out the values of all the variables on that line.
Please edit your post and wrap your code with code tags:
YOUR CODE HERE
to get highlighting and preserve formatting.