When java EE Web development * .jsp page <% @ show "The superclass" javax.servlet.http.HttpServlet "was not found on the Java Build Path" error, webcontent folder always appears red x

When we were Java web development with Eclipse, this error may occur: The superclass javax.servlet.http.HttpServlet was not found on the Java Build Path. How can we solve this problem?

We encountered an error is shown below:

We have right-click the folder error, as follows:

We click on the "Configure Build Path", as follows:

 

 

We then click on "Add Library", as follows:

We selected the image above marked options, then click Next, as follows:

We then click "Finish", as follows:

We then click on the "normal" to complete the setting. So that my mistake will disappear,