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ArrayList Comparistion

Posted on 2006-10-25
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Last Modified: 2008-02-01
Hi

I have two arrayalist
 
ArrayList a = {2,3,4, 5,6}
ArrayList b = {1,2,3}

a-b = {4,5,6}
b-a = {1}

My question is there any built in fuction that will perform minus operation of two array list.
If there is no builtin how do we perform. I think there should be a built in not sure how we can perform
Can you help we a running example.

Thanks
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Question by:basirana
5 Comments
 
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Expert Comment

by:avsrivastava
ID: 17805516
public boolean removeAll(Collection c)
http://java.sun.com/j2se/1.5.0/docs/api/java/util/AbstractCollection.html#removeAll(java.util.Collection)

or iterator over one arraylist and keep using
public boolean remove(Object o)

http://java.sun.com/j2se/1.5.0/docs/api/java/util/ArrayList.html#remove(java.lang.Object)

Hope this helps.
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hoomanv earned 500 total points
ID: 17805570
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Author Comment

by:basirana
ID: 17805659
Thanks for Response Have great time
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Expert Comment

by:gambistics
ID: 17805665
Here is an example of how to do that:

ArrayList<Integer> a=new ArrayList<Integer>();
ArrayList<Integer> b=new ArrayList<Integer>();
      
Collections.addAll(a,1,2,3,4,5,6);
Collections.addAll(b,1,2);
            
a.removeAll(b);
      
System.out.println(a); // will print [3,4,5,6]

An important point: Make sure the element type (Integer in this case) provides a working hashCode and equals implementation.

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Expert Comment

by:avsrivastava
ID: 17805695
Example:

   ArrayList a = new ArrayList(), b = new ArrayList();
   a.add(new Integer(1));
   a.add(new Integer(2));
   a.add(new Integer(3));
   a.add(new Integer(4));
   a.add(new Integer(5));
   b.add(new Integer(2));
   b.add(new Integer(4));
   System.out.println(a.toString()+b.toString());
   a.removeAll(b);
   System.out.println(a.toString()+b.toString());

Output:
[1, 2, 3, 4, 5][2, 4]
[1, 3, 5][2, 4]
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