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Thread: Removing objects from a hashSet

  1. #1
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    Default Removing objects from a hashSet

    Hey there,

    I'm a bit stuck. I'm desperatly trying to find a way to remove from a HashSet, but everytime I do it, I get the error incompatible types- found java.lang.Objecs but expected Bag, while pointing at the line

    Bag aCan = it.next();

    I don't understand why it expects Bag- as far as I can see, on that line Bag is there. Any help would be great- I'm very much a beginner with this! (Which probably shows)

    import java.util.HashSet;
    import java.util.Iterator;
     
    /**
     * Bag class
     */
    public class Bag
    {
        private HashSet Bag = new HashSet<Can>();
     
        /**
         * Constructor for objects of class Bag
         */
     
        public Bag(int BagAmount)
        {
           HashSet<Can> Bag = new HashSet<Can>();
           for (int i = 0;
                    i < BagAmount;
                    i++){
         Bag.add(new Can());
    }
        }
     
        /**
         * methods
         */
     
        public int CanCount()
     
        {
            return Bag.size();
        }
     
        public Can removeCan()
        {
          if (Bag.size() > 0);
          Iterator it = Bag.iterator();
          while (it.hasNext()) {
          Bag aCan = it.next();
          Bag.remove();
        }
    }
    }


  2. #2
    Administrator copeg's Avatar
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    Default Re: Removing objects from a hashSet

    First, double check the naming in your code...never name an instance variable identical to its containing class...eg the Bag HashSet identical name as the class which contains it. Second, be careful modifying a Collection while iterating over that collection - depending upon the implementation you could end up getting a ConcurrentModificationException. Lastly, the HashSet generics you define are for can, and unless Bag and Can are somehow related you cannot perform this operation.

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