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Collection - Chap 7 (Maps) (Problem in Understanding an example in K&B SCJP 1.6)

Tanya Shetty
Ranch Hand

Joined: Jun 17, 2009
Posts: 40



Output :
Dog key
New Dog Key
collection.Dog@35ce36
collection.Dog@757aef
null
null
New Dog Key
New Dog Key


Question
Object ref "d" is used as a key for the value "New Dog Key". the hashcode for object of class Dog,
is used as the length of variable "name".
As per the SCJP 1.6, Chap 7 , when the value of "name" for object ref "d" is changed to "magnolia" ie. d.name = "magnolia"; the object will be searched in a hash bucket other than that where the object was placed originally ie hash bucket returned when value of "name" was diego.

Hence, the System.out.println(m.get(d)); should return null!!
But, as you can see the code returns an output with value "new Dog Key".

I dont understand ?

Ankit Garg
Sheriff

Joined: Aug 03, 2008
Posts: 9304
    
  17

Read this or this...


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Anastasia Sirotenko
Ranch Hand

Joined: Jul 20, 2009
Posts: 64
be careful with function names
here you have hashcode() function, not hashCode(), as a result the program uses the default object hashCode() for d reference wich does not depend on any Dog field

In real life you can mark your overridden method by @Override annotation, wich will save you some nerve, but for exam we just have to be careful with such "typo's" in code


[SCJP 6.0]
 
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subject: Collection - Chap 7 (Maps) (Problem in Understanding an example in K&B SCJP 1.6)