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equals() question required

PETER CARTER
Ranch Hand

Joined: Aug 28, 2004
Posts: 70
Given that b and c refer to instances of wrapper classes, which two statements are
true? (Choose two)
A. b.equals(b) returns true.
B. b.equals(c) returns the same result as b == c.
C. b.eqials(c) can return false even if c.equals(b) returns true.
D. b.equals(c) throws an exception if b and c are different wrapper types.
E. b.equals(c) returns false if the type of wrapper objects being compared are different.
Answer: B, C
But I belive the right answer is :A,E.
Do you follow me ?
Thanks !!
Sandeep Jindal
Ranch Hand

Joined: Aug 25, 2003
Posts: 180
Hi,

I also think A,E. Please verify the question once again.
Jessica Sant
Sheriff

Joined: Oct 17, 2001
Posts: 4313

hmmm its been awhile since I've played with wrappers... so I wrote a bit of code to test it out... I think A, B and E are correct ?? Try writing some snippets to prove me right or prove me wrong.



Result:


- Jess
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aishwarya mathur
Greenhorn

Joined: Sep 03, 2004
Posts: 22
Jessica ,

Can we justify the above question posted by Peter Carter without knowing the contents for the wrapper objects. I mean as you have shown in ur code snippet
Integer i = new Integer(2); ---- how can we get the answers without the contents of the objects, as the above instruction shows 2.
Tom Tolman
Ranch Hand

Joined: Sep 02, 2004
Posts: 83
b is incorrect. Try the following code:



It outputs

a not == b
a equals b

They are two different wrapper objects which both wrap 2.
tao wu
Greenhorn

Joined: Sep 18, 2004
Posts: 8


Code from j2dk1.4.2

I think answer is A,E


Boy From PRC<br />SCJP1.4
 
I agree. Here's the link: http://aspose.com/file-tools
 
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