Java NullPointerException when adding Socket to Collection
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I have looked at my code and tried to identify why I am getting a NullPointerException when adding a socket to my collection. The PrintWriter and BufferedReaders initialize with the socket and even send the welcome message fine, so I know that clientSocket is not NULL.

Here is the exception:

    java.lang.NullPointerException
	    at Client.run(Client.java:27)
	    at java.lang.Thread.run(Thread.java:680)

Here is my Client.java: http://pastebin.com/NAPuEFgh

Here is my Main.java: http://pastebin.com/tZ42VcBi


Maybe I am not understanding the collections methods correctly, as I am not extremely familiar with them, but I appreciate the help.