I have two lists. For example:
A = {21, 41, 96, 02}
B = {21, 96, 32, 952, 1835}
What I want is this as a result: R = {32, 952, 1835}
Like this:
After this I want to add the result R to A:
A = {21, 41, 96, 02, 32, 952, 1835}
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3How is that going for you?khelwood– khelwood2014-10-28 09:18:05 +00:00Commented Oct 28, 2014 at 9:18
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2Did you wrote any code ? Please, post it.ortis– ortis2014-10-28 09:18:24 +00:00Commented Oct 28, 2014 at 9:18
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1And what is your question?user462963– user4629632014-10-28 09:18:27 +00:00Commented Oct 28, 2014 at 9:18
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@JamesFox No. Please look at the image. I only want the red partJosh– Josh2014-10-28 09:22:34 +00:00Commented Oct 28, 2014 at 9:22
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are you want to compare these two values ??dneranjan– dneranjan2014-10-28 09:22:40 +00:00Commented Oct 28, 2014 at 9:22
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Show 4 more comments
4 Answers
It's simple :)
List<Integer> a = new ArrayList<>(Arrays.asList(21, 41, 96, 02));
List<Integer> b = new ArrayList<>(Arrays.asList(21, 96, 32, 952, 1835));
b.removeAll(a)
// now list b contains (32, 952, 1835)
a.addAll(b);
// now list a contains (21, 41, 96, 02, 32, 952, 1835)
2 Comments
vegemite4me
This answers part of the question, finding out
R.
Jakub Kubrynski
@vegemite4me right - I've missed second part - thanks!
So you want to make A = A U B. To do this, you can search for each element of B in A and add the element to A if the search fails. However, making too much search on a list is not recommended.
I would recommend using a HashMap. Create a HashMap and loop through A and B putting anything you see into the map. After that, you can convert map back to a list.
[If you want the order to be the same as in the example, you should convert A to a map. Then you should go through B and for each failed map.get(element) you should be adding that element of B to A.]
Comments
Try this :
import org.apache.commons.collections.CollectionUtils;
[...]
// Returns a Collection containing the exclusive disjunction (symmetric difference) of the given Collections.
Collection disJointList = CollectionUtils.disjunction(a, b);
//To check
for (Object object : disJointList) {
System.out.println(disJointList);
//output is {32, 952, 1835}
}
a.addAll( disJointList );
