The word is "you", not "u". Spelling counts in Java, as with all
computer languages, so it is good to practice good spelling in the
Java forums, too. For example, if you try to use "thow" or "thows" in
your code to mean 'throw' or 'throws', respectively, it will not
compile.
Also, it is conventional to state your question in the body of your
post, not just the subject line. It makes it marginally easier for
others to follow the conversation in these discussions.
Your question about the difference between 'throw' and 'throws' is
completely answered in the Java Language Specification (JLS):
<
http://java.sun.com/docs/books/jls/third_edition/html/
exceptions.html>
That section details the semantics of the 'throw' command.
The 'throws' keyword is explained in detail in
<
http://java.sun.com/docs/books/jls/third_edition/html/
classes.html#8.4.6>
for methods and
<
http://java.sun.com/docs/books/jls/third_edition/html/
classes.html#8.8.5>
for constructors.
The tutorial for exceptions is at
<
http://java.sun.com/docs/books/tutorial/essential/exceptions/
index.html>
You will find java.sun.com an excellent first source of information
for Java programming. The JLS and the tutorials are where you should
start for language understanding; the API Javadocs
<
http://java.sun.com/javase/6/docs/api/>
for information about the standard APIs.