JSP comments

You can use two types of comments within a JSP. The first comment style, known as an output comment, enables the comment to appear in the output stream on the browser. This comment is an HTML formatted comment whose syntax is:

<!– comments … –>

The second comment style is used to fully exclude the commented block from the output and is commonly used when uncommenting a block of code that so that the commented block is never delivered to the browser. The syntax is:

<%– comment text –%>

 

The first comment <!– –> block excludes all the static content

  • line 1<br/> as text content
  • <%=line2%> will be rendered as text content

But the scriptlets between the comment is still runable. Therefore, line 3 is printed.

The 2nd comments <%– –%> excludes everything inside it. Therefore, line5 is not assigned in the scriplets and keep the original value and is not displayed.

Step 1 Create New Dynamic Web Project

Step 1.1 Create New Project

Go to File->New->Others… Select Dynamic Web Project under Web category then click Next. TypeServletDemo or whatever name you want in the Project name field.

Step 1.2 Configure Target Runtime

  • Click New Runtime… button under Target Runtime.
  • Select Apache Tomcat v7.0. Click Next.
  • Click Browse button to specify Tomcat Server installation directory. The select the folder then click Ok.
  • Click Installed JREs… button to add/remove or edit JRE definition. Remove existing one; then click Add button to configure new one. Select Standard VM; then click Next. Click Directory button to select the root folder of JDK installation. Select the folder then click Ok. Click Finish.
  • Check the JDK then click Ok.
  • Change JRE to the JDK then click Finish.
  • Click Finish the finish the project creation.

Step 2 Create New JSP File

  • Right click to the project or WebContent folder, select New -> JSP File from the menu.
  • You can choose any name, for example commentsDemo.jsp
  • Click Finish.
  • Eclipse IDE will generate some boilerplate code. We just clear all its content and replace with the followings code:

Step 3 Configure Tomcat

Select Servers window; in case it’s not there, go to Windows -> Show View-> Others… Select Server -> Servers; then click Ok.

If this is the first time you are creating a server, in the Servers area you will see a link as No servers are available click this link to create a new server. Click the link.

Define a New Server window will be opened, In Select the server type. Select Apache -> Tomcat v7.0 Server. Then click Finish.

Step 4 Deploy The Application

  • Right click to the Tomcat Server select Add and Remove.
  • Move the application (JSPDemo) from Available column to Configured. Then click on Finish to deploy it to tomcat server.

Step 5 Start Tomcat Server

Right click on the tomcat server and choose Start or simply click on the green start icon to start the server.

Step 6 Run The JSP

We assume that you install tomcat on default port (8080) and project name is JSPDemo. Open web browser and type:

http://localhost:8080/JspDemo/commentsDemo.jsp

Output

Note: for JSP, you don’t need to Clean & Build the project or restart the tomcat server before running. You just change the code, save the changes and run.

For java classes, you need to Clean & Build the project to re-compile the code. In case register new servlet, change settings in web.xml or server.xml… you need to Clean & Build the project and restart tomcat server.