JSP Interview Questions and Answers
Related differences
Ques 21. What are the two kinds of comments in JSP and what’s the difference between them.
<%– JSP Comment –%>
<!– HTML Comment –>
Ques 22. What is a Expression?
An expression tag contains a scripting language expression that is evaluated, converted to a String, and inserted where the expression appears in the JSP file. Because the value of an expression is converted to a String, you can use an expression within text in a JSP file. Like
<%= someexpression %>
<%= (new java.util.Date()).toLocaleString() %>
You cannot use a semicolon to end an expression
Ques 23. What is a Declaration?
A declaration declares one or more variables or methods for use later in the JSP source file.
A declaration must contain at least one complete declarative statement. You can declare any number of variables or methods within one declaration tag, as long as they are separated by semicolons. The declaration must be valid in the scripting language used in the JSP file.
<%! somedeclarations %>
<%! int i = 0; %>
<%! int a, b, c; %>
Ques 24. What is a Scriptlet?
A scriptlet can contain any number of language statements, variable or method declarations, or expressions that are valid in the page scripting language.Within scriptlet tags, you can
1.Declare variables or methods to use later in the file (see also Declaration).
2.Write expressions valid in the page scripting language (see also Expression).
3.Use any of the JSP implicit objects or any object declared with a <jsp:useBean> tag.
You must write plain text, HTML-encoded text, or other JSP tags outside the scriptlet.
Scriptlets are executed at request time, when the JSP engine processes the client request. If the scriptlet produces output, the output is stored in the out object, from which you can display it.
Ques 25. Why are JSP pages the preferred API for creating a web-based client program?
Because no plug-ins or security policy files are needed on the client systems(applet does). Also, JSP pages enable cleaner and more module application design because they provide a way to separate applications programming from web page design. This means personnel involved in web page design do not need to understand Java programming language syntax to do their jobs.
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