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general questions about jsp

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Join Date: Nov 2007

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emilio

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general questions about jsp

Aug 6th, 2008

i just starter to learn jsp and i have few questions.

1) in my jsp project i have jsp page and java classes that defined as jsp beans.
my jsp page contains submit button. is there a way to define that each time i press the
button the program will run a function from one of the java classes that defined as beans ?

2) is there a command that can make the jsp page to be runned again?
at the end of my jsp page i want to write:

 Help with Code Tags 
 jsp Syntax (Toggle Plain Text) 
   <% if (...) { %>
         run the page again
     <% } %>
   <% if (...) { %>
         run the page again
     <% } %>

so when i run the page at the end if the if's condition is true the page will be runned again.

3) in my jsp page i have a select form:

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 jsp Syntax (Toggle Plain Text) 
<form><SELECT SIZE=1 align="center" name="mode"> 
                       <OPTION SELECTED VALUE = "UU"> user vs user </OPTION>
                       <OPTION  VALUE = "UC"> user vs computer </OPTION>
                       <OPTION  VALUE = "CU"> computer vs user </OPTION>
                       </SELECT></form>
<form><SELECT SIZE=1 align="center" name="mode"> 
                       <OPTION SELECTED VALUE = "UU"> user vs user </OPTION>
                       <OPTION  VALUE = "UC"> user vs computer </OPTION>
                       <OPTION  VALUE = "CU"> computer vs user </OPTION>
                       </SELECT></form>

how can i get the string of the current selected option ?

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Join Date: Aug 2008

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nikhildoomra nikhildoomra is offline

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Re: general questions about jsp

Aug 7th, 2008

hey u can use
response.redirect("this page") to run the page again...

nd for... selecting a string u can retrieve it through javascript...
also u can get value by using... request.getParameter("mode");

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Join Date: Nov 2007

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emilio

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Re: general questions about jsp

Aug 7th, 2008

i tryed to get selected option like this:

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 jsp Syntax (Toggle Plain Text) 
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <select size="1" name="mode">
            <option value="o1">1</option>
            <option value="o2">2</option>
            <option value="o3">3</option>
        </select>  
 
        <% String s = request.getParameter("mode"); %>
        <p><%=s%>
    </body>
</html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <select size="1" name="mode">
            <option value="o1">1</option>
            <option value="o2">2</option>
            <option value="o3">3</option>
        </select>  
        
        <% String s = request.getParameter("mode"); %>
        <p><%=s%>
    </body>
</html>

it gives me null. what am i doing wrong ?

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Join Date: Dec 2004

Posts: 4,185

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peter_budo peter_budo is offline

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Re: general questions about jsp

Aug 7th, 2008

1) None of the drop-down option was declared as default to display
<option value="o2" selected="selected">2</option>
2) You want to run this or something similar in functionality not technology

 Help with Code Tags 
 JSP Syntax (Toggle Plain Text) 
<% String s = request.getParameter("mode"); %>
<p><%=s%>
<% String s = request.getParameter("mode"); %>
<p><%=s%>

when a change was detected on drop-down not immediately after you display it on screen. For such thing JavaScript would be more suitable

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(~100 BC)
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Join Date: Nov 2007

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emilio

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Re: general questions about jsp

Aug 7th, 2008

i tried it like this:

 Help with Code Tags 
 jsp Syntax (Toggle Plain Text) 
<select size="1" name="mode">
            <option value="o1" selected>1</option>
            <option value="o2">2</option>
            <option value="o3">3</option>
        </select>  
 
        <p><%=(request.getParameter("mode"))%>
<select size="1" name="mode">
            <option value="o1" selected>1</option>
            <option value="o2">2</option>
            <option value="o3">3</option>
        </select>  
        
        <p><%=(request.getParameter("mode"))%>

i think it's the right syntax when the first option is pre selected. it still doesnot work when i run the page.

i'm not allowed to use javascript only jsp

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Join Date: Dec 2004

Posts: 4,185

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peter_budo peter_budo is offline

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Re: general questions about jsp

Aug 7th, 2008

Have look at chap1 from Beginning JSP, JSF and Tomcat Web Development: From Novice to Professional pg11 onwards can be to some interest to you. Source code is available for download too