In this JSP tutorial, you will learn about JSP tags, list of the tags used in Java Server Pages, declaration tag, general syntax of declaration tag, expression tag and general syntax of expression tag.
Tags are a vital concept in Java Server Pages (JSP). Below is a list of tags used in JSP. This section discusses Declaration Tag and Expression Tag in detail; syntax, usage with examples and explanations for both.
List of the tags used in Java Server Pages:
- Declaration tag
- Expression tag
- Directive tag
- Scriptlet tag
- Action tag
Syntax, usage and example of Declaration Tag and Expression Tag:
Declaration tag is used to define functions, methods and variables that will be used in Java Server Pages.
Notation of the Declaration tag is shown below:
At the start of Declaration tag one must place <%! Inside Declaration tag one can declare variables or methods. Declaration tag ends with the notation %>. Also care must be taken to place a semicolon that is ; at the end of each code placed inside Declaration tag.
General syntax of Declaration Tag:
<%! //start of declaration tag
statement2; //variables or methods declaration
%> //end of declaration tag
Expression tag is used to display output of any data on the generated page. The data placed in Expression tag prints on the output stream and automatically converts data into string. The Expression tag can contain any Java expression used for printing output equivalent to out.println().Thus, an expression tag contains a scripting language expression which is evaluated, automatically converts data to a String and the outputs are displayed.
Notation of Expression tag is shown below:
Expression tag must begin with <%= Inside Expression tag, the user embeds any Java expression. Expression tag ends with the notation %>.
NOTE: Expression should not contain a semicolon between codes, as with Declaration tag.
General syntax of Expression Tag:
Exfdate: <%= new java.util.Date() %>
Above example displays current date and time as Date() is placed inside the Expression tag <%= %>