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Junit assertCollection?

Posted on 2011-03-14
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Last Modified: 2012-05-11
What's the best way to unit test that 2 collections are the same.
(Not the same object, but each element value of one collection is in the other, and vice versa)
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Question by:allelopath
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6 Comments
 
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Expert Comment

by:for_yan
ID: 35132060

Are all objects in your collections unique?
Or you may have two equal options present in any of your two collections?

if they are unique then if the sizes of both collections are equal,
and then you just traverse one collection and check that
all elements of this coll;ection are present in the second collection then
tyour collections are the same in the sense you mentioned
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by:for_yan
ID: 35132107

if my question above has the anser "yes" then this method should work:

boolean areTheyEqual(ArrayList a1, ArrayList a2){
if(a1.size() != a2.size() ) return false;

for(int j=0; j<a1.size(); j++){
if(!a2.contains(a1.get(j)){
return false;
}
}
return true;

}

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Accepted Solution

by:
for_yan earned 500 total points
ID: 35132225

I think this should work even if each collection
has identical items:

boolean areTheyEqual(ArrayList a1, ArrayList a2){
if(a1.size() != a2.size() ) return false;
for(int j =0; j<a1.size(); j++){
int count1 = 0;
for(int k=0; k<a1.size(); k++){
if(a1.get(j).equals(a1.get(k))count1++;

}
int count2 = 0;
for(int k=0; k<a2.size(); k++){
if(a1.get(j).equals(a2.get(k))count2++;

}
if(count1 != count2)return false;

}
retrurn true;

}
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Author Comment

by:allelopath
ID: 35132239
Thanks.
Looks like I could also use Apache Commons CollectionsUtils
CollectionUtils.isEqualCollection(actual, expected);
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Expert Comment

by:for_yan
ID: 35132266
Yes, you are right - that probably would be better.
But it is nice to invent the wheel also :)
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Expert Comment

by:CEHJ
ID: 35132479
coll1.removeAll(coll2);
boolean identical = coll1.size() == 0;
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