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sorting by a primitive int field

saima kanwal
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Joined: Oct 05, 2009
Posts: 148
I am trying to sort my array list using comparator. please review my code and solve my problem. I want to sort my array list by int type isbn number of book. My code is as follows:

And it does not compile because I am using the compare to method with int. How am i going to compare int (primitive)? please modify my code.


SCJP 6.0 (86%) SCWCD 5 (94%)
Christophe Verré

Joined: Nov 24, 2005
Posts: 14688

Hint: The Integer class is comparable

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Ankit Garg

Joined: Aug 03, 2008
Posts: 9403

In the above statement, isbn is a primitive so you can't call compareTo method on it. But since it is a primitive, you can use comparison operator on it. So if you see the source code of Integer class, the compareTo method is implemented like this

You can implement your compareTo method in the same way too. To make it even simpler, you can just write

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