Is returning invalid integer from doStartTag() is equivalent to returning EVAL_BODY_INCLUDE ?

[Bindu Lakhanpal]

If i return invalid integer value from doStartTag() in following code,no exception occurs,which is understandable since return type of doStartTag() is integer.But what i got as output is as if EVAL_BODY_INCLUDE (which is equal to 1)is returned.

//Returning Invalid integer from doStartTag()

package com;   
import javax.servlet.jsp.*;   
import javax.servlet.jsp.tagext.*;   
import java.io.*;   
public class MyOwnCustomTag extends TagSupport   
               {   
                     JspWriter out;   
                     public int doStartTag() throws JspException   
                            {  out=pageContext.getOut();   
                                      try{   
                                         out.print("in doStartTag with 23(invalid) return value");   
                                           }   
                                     catch(IOException ex)   
                                          {   
                                        throw new JspException("IOException " +ex.toString());   
                                          }   
                            return 23;   
                            }   
                     public int doAfterBody()throws JspException   
                           {   
                                      try{   
                                         out.print("-----in doAfterBody");   
                                          }   
                                       catch(IOException ex)   
                                         {   
                                         throw new JspException("IOException " +ex.toString());   
                                         }   
    
                                       return SKIP_BODY;   
                           }   
                    public int doEndTag() throws JspException   
                               {   
                                        try{   
                                          out.print("-----in doEndTag");   
                                             }   
                                        catch(IOException ex)   
                                            {   
                                          throw new JspException("IOException " +ex.toString());   
                                             }   
                                   return SKIP_PAGE;   
                                }   
                  }  

The out put is as follows:

in doStartTag with 23(invalid) return value This is tag body which can be jsp -----in doAfterBody-----in doEndTag
Is it container specific behaviour ( I am using Tomcat )or is it what jsp spec says?
Even if i return other values like SKIP_PAGE (which is valid for doEndTag()), i got same output as above.

[Christophe Verré]

I don't think that it's explicitly written in the spec. I think it's container dependent, so you'd better be sure to return the correct value.

[Bindu Lakhanpal]

Ok.Thanks.

If i returned invalid integer from doAfterBody(),it behaved as if SKIP_BODY is returned.
Returning invalid integer from doEndTag() gave output as if EVAL_PAGE is returned.
These are default return values unlike EVAL_BODY_INCLUDE in case of doStartTag().

If such a question comes in exam(although probability is low),should the answer be "container dependent"

[Christophe Verré]

I think you have to know which constant can be returned. There is no container dependent question at the exam.

[Chinmaya Chowdary]

Hi Bindu.
Make sure that we should not return the value '0'(which is default return value of SKIP_BODY) in doStartTag(). If we return, the body will not be evaluated. Tomcat will checks that condition.
Tomcat is not performing may conditional checks incase of ClassicTags. If they performs, if affect on performance.