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<?xml version='1.0'?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>

  <head>

    <title>JET Expressions Syntax Reference</title>

    <link charset="ISO-8859-1" href="../../book.css" rel="STYLESHEET"
     type="text/css"/>

  </head>

  <body>

    <h2>JET Expressions Syntax Reference</h2>

    <p>JET Templates may emit the result of a Java expression by 
    enclosing the Java expression between the characers 
    <code>&lt;%=</code> and <code>%&gt;</code>.</p>

    <h3>Valid Expressions</h3>

    <p>Expressions contain valid Java expressions. Java expressions are 
    not complete statements, and in particular, they do not include a 
    semi-colon (;). Expressions may access any Java element inscope 
    Java elemement, including fields and methods declared in 
    <a href="jetSyntaxDeclarations.xhtml">Java declarations</a>, or in 
    <a href="jetSyntaxScriptlets.xhtml">Java scriptlets</a>, or 
    <a href="implicitJavaObjectsReference.xhtml">Implicit Java 
    Objects</a>.</p>

    <p>The emitted Java code for the template will evaluate the Java 
    expression and convert the result to a string (if necessary). The 
    following are examples of Java expressions:</p>

    <pre>The name of the class executing is: &lt;%= this.getClass().getName() %&gt;

Although slightly silly, expression may be constant, like &lt;%= 5 %&gt; and &lt;%= &quot;hello&quot; %&gt;.</pre>
    <h3>Invalid Expressions</h3>

    <p>Any syntax error in the Java expression will result errors in 
    the emitted Java code. The JET compiler does not attempt to 
    correlate the Java compile error back to the JET template. Some 
    examples:</p>

    <pre>&lt;%= 3 + 4; %&gt; &lt;%-- semicolon not allowed in Java expressions --%&gt;</pre>
    <h3>Escaping Expression characters</h3>

    <p>To emit the characters <code>&lt;%=</code> in a templates 
    output, enter <code>&lt;\%=</code>. To emit <code>%&gt;</code>, 
    enter <code>%\&gt;</code></p>

  </body>

</html>

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