By using Follow code, it is possible to show error message if java run-time not installed in client mechine
<!DOCTYPE html>
<html>
<body>
<script>
if (navigator.javaEnabled()) {
//Java is enabled
}
else
{
document.write("Error:Java is Disabled or Java Not Installed<br>Download and Insatall java from <a href=\"http://www.java.com/en/download/index.jsp\">http://www.java.com/en/download/index.jsp</a>");
}
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<body>
<script>
if (navigator.javaEnabled()) {
//Java is enabled
}
else
{
document.write("Error:Java is Disabled or Java Not Installed<br>Download and Insatall java from <a href=\"http://www.java.com/en/download/index.jsp\">http://www.java.com/en/download/index.jsp</a>");
}
</script>
</body>
</html>