Nested Tag example in HFSJ

[Kevin Chapple]

Hi everyone,

I've been trying to get my head round nested custom tags and have a query about the Nestedtag example in HFSJ.

The code in the tag is

    

public class NestTag extends TagSupport {

	
	private int nestLevel=0;

	public int doStartTag() throws JspException {

		nestLevel=0;

		Tag parent = getParent();

		while(parent!=null) {
			parent = parent.getParent();
			nestLevel++;
		}
	


		try {
		pageContext.getOut().println("<br>Tag nested Level: " + nestLevel);
		}catch(IOException ex){
			throw new JspException("IOException- " +ex.toString());
		}


		return EVAL_BODY_INCLUDE;
	}


}

In the JSP

 
<meTags:nestTag>
	<meTags:nestTag>
		<meTags:nestTag/>
	</meTags:nestTag>
</meTags:nestTag>
   

With output

Tag nested Level: 0
Tag nested Level: 1
Tag nested Level: 2



I dont really understand the code and how the out put is generated. I am confused about nested Tags and what order the tag returns output when they are nested.

In this example does the outermost Nested tag print out the ' Tag nested Level:0' first because the getParent() tag returns 'Null'?Then does the first inner tag return the 'Tag nested Level:1' due to get Parent() returning a non null result once which increments the 'nestLevel' by 1? Then the most nested tag incrementing the 'nestLevel' twice due to getParent() being called twice until returning null

I dont understand the flow of actication of the tags in the example and why the output is what it is.

Thanks in advance for taking the time to review my query