not print the text

Request is not going to the server.
you are not submitting the form. So how can code inside
<% %>
can execute.

So how can code inside
<% %>

Whats <%%> got to do with form submission? Which text is not getting printed, clarify your question properly.

<form name="form1">
<input type="button" name="b" style="background-color:#FF0000 ">
Above part in your code is not useful.

Check with this code fragment. You don't need to submit this to server. This is only jsp file. so "hello" must be print in browser.

Putting Java code in a JSP in this manner has been discredited for over 8 years now. It's 2010 and it's time to start writing JSP like grown-ups.

Ditch the scriptlets and learn the JSTL and EL for properly writing JSPs.