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<TITLE>Implementing Conditional Content on a JSP Page (Java Developers Almanac Example)
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<META CONTENT="Patrick Chan" NAME="AUTHOR">
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<h1>The Java Developers Almanac 1.4</h1>
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<A HREF="../javax.servlet.jsp/pkg.html">javax.servlet.jsp</A><font color="#666666" class="xsmall-font">
[18 examples]
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<B><A HREF="../javax.servlet.jsp/pkg.html#Java Server Pages Output">Java Server Pages Output</A></B><font color="#666666" class="xsmall-font">
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<h3>e1059. Implementing Conditional Content on a JSP Page</h3>
Any non-JSP code in a JSP file is called template text and is
automatically written to the output stream. By wrapping template text
fragments in scriptlets, it is possible to dynamically choose which
fragment to generate.
<P> These examples generate different template text depending on
the value of request parameters:
<pre> <% if (<font color="#0066ff"><i>"someValue"</i></font>.equals(request.getParameter(<font color="#0066ff"><i>"param1"</i></font>))) { %>
Generate this template text if param1 equals someValue
<% } else { %>
Otherwise generate this template text
<% } %>
<% switch (Integer.parseInt(request.getParameter(<font color="#0066ff"><i>"param2"</i></font>))) {
case 0: %>
Generate this template text if param2 equals 0
<% break;
case 1: %>
Generate this template text if param2 equals 1
<% break;
default: %>
Generate this template text if param2 equals anything else
<% } %>
</pre>
See also <a href="../javax.servlet.jsp.jstl.core/if.html" class="eglink"><b>e1069</b> Conditionally Generating Output Using JSTL in a JSP Page</a>.
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<b>Related Examples</b></font></td>
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e1057. <a class="eglink" href="comment.html?l=rel">
Commenting a JSP Page
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e1058. <a class="eglink" href="expr.html?l=rel">
Generating Dynamic Content on a JSP Page
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e1060. <a class="eglink" href="error.html?l=rel">
Handling Unhandled Exceptions in a JSP Page
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See also:
<a class="eglink" href="/egs/javax.servlet.jsp/pkg.html?l=rel#Java%20Server%20Pages">
Java Server Pages
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<a class="eglink" href="/egs/javax.servlet.jsp/pkg.html?l=rel#Java%20Server%20Pages%20Headers">
Java Server Pages Headers
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<a class="eglink" href="/egs/javax.servlet.jsp/pkg.html?l=rel#Java%20Server%20Pages%20Input">
Java Server Pages Input
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