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The dot(.) operator and [] operator

Kim Lauwers
Ranch Hand

Joined: Sep 23, 2005
Posts: 31
Hello everyone,

Is there a site or something witch explanes me these two operators because I find them rather difficult.

Or if someone can explain me this shortly.

I'm using HFSJ for studying.

thx


Programming today is a race between Software Engineers striving to build bigger and better idiot-proof Programs, and the Universe trying to produce bigger and better idiots.<br />So far, the Universe is winning!
Kim Lauwers
Ranch Hand

Joined: Sep 23, 2005
Posts: 31
Little question about it.

When a have a map:
java.util.Map someMap = new java.util.HashMap();
someMap.put("key","value");

someMap["key"] -->will return value?
map[key]--> wil return null?

correct?
Balasubramani Dharmalingam
Ranch Hand

Joined: Dec 06, 2004
Posts: 116
${someMap["key"]}
In this case it will return the object from someMap that mapped to string "key" will be return.

${someMap[key]}
In this case the value for the key ( equivalent to ${key} ) is evaluated then the object mapped for that value will be return.


Balasubramani SD,<br />SCJP 1.4,SCWCD 1.4,SCJP 5.0<br /><a href="http://sd.balasubramani.googlepages.com" target="_blank" rel="nofollow">www.sd.balasubramani.googlepages.com</a>
Richard Green
Ranch Hand

Joined: Aug 25, 2005
Posts: 536
java.util.Map someMap = new java.util.HashMap();
someMap.put("key","value");

someMap["key"] --> request.getAttribute(someMap.get("key")) --> value
someMap[key]--> request.getAttribute(someMap.get(request.getAttribute("key")) --> null


MCSD, SCJP, SCWCD, SCBCD, SCJD (in progress - URLybird 1.2.1)
 
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