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Attributes Doubt??

Joe Harry
Ranch Hand

Joined: Sep 26, 2006
Posts: 9345
    
    2

Guys,

I have the doubt in the code below that I got from David Bridgewater's book,

10 // "out" is the response's PrintWriter
11 out.write("<H2>Context (Application) Scope</H2>");
12 ServletContext context = getServletContext();
13 String myAttributeName = "com.osborne.conductor";
14 context.setAttribute(myAttributeName, "Andre Previn");
15
16 enum = context.getAttributeNames();
17 while (enum.hasMoreElements()) {
18 attrName = (String) enum.nextElement();
19 attrValue = context.getAttribute(attrName);
20 out.write("<BR />Attribute name: <B>" + attrName + "</B>, value: <B>"
21 + attrValue + "</B>");
22 }
23 String conductor = (String) context.getAttribute(myAttributeName);
24 out.write("<BR /> Just used getAttribute() to obtain "
25 + myAttributeName + " whose value is " + conductor);
26
27 context.removeAttribute(myAttributeName);
28 context.setAttribute(myAttributeName, null);
29
30 out.write("<BR />Value of attribute " + myAttributeName + " is now "
31 + context.getAttribute(myAttributeName));

I want to know what like 18 and 19 does??


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Micheal John
Ranch Hand

Joined: Nov 01, 2006
Posts: 344
getAttributeName() return type is enumeration. The line 18 and 19 does the iteration and get all the attributes in the context scope one by one..


Micheal John
SCJP 1.4 (86%), SCWCD 1.4 (86%), SCBCD 1.3 (85%), SCDJWS (Just Started...) - Satisfaction Lies in Our EFFORT, Not in the ATTAINMENT
Joe Harry
Ranch Hand

Joined: Sep 26, 2006
Posts: 9345
    
    2

Michael,

My doubt is that, in the book they did not show what type the attrName and attrValue are... They must be Strings right?? I got this one. Thanks!
Gopikrishna krishna
Greenhorn

Joined: Feb 21, 2007
Posts: 1
yes you are right. Both of them are of String data type.
Swati Udas
Ranch Hand

Joined: Aug 18, 2004
Posts: 121
Regarding the code here I have a doubt about line 27 and 28..
Can we set an attribute to null when its already been removed in previous line ?


SCJP 1.4 (90%)<br />SCWCD 1.4 (88%)
Alex Zhang
Greenhorn

Joined: Feb 21, 2007
Posts: 3
I guess it works like a map. you remove one entry, then put another entry in using the same key.


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