removing element from list

Question

I have 2 lists, and depending on a parameter I remove an element from 1 of the 2 lists. I then loop through the lists for additional processing. However even though the list has lost 1 element, the list.size() is still the same causing a java.lang.IndexOutOfBoundsException. Is there anything I can do to fix this?

    System.out.println(high_list_price.size());

    if(first_hit.equals("low")){
        high_list_date.remove(high_list_date.size()-1);
        high_list_price.remove(0);
        high_list_percent.remove(0);
    }
    if(first_hit.equals("high")){

        low_list_date.remove(low_list_date.size()-1);
        low_list_price.remove(0);
        low_list_percent.remove(0);
    }

    System.out.println(high_list_price.size());

    for(int tt = 0;tt < low_list_date.size();tt++){
        System.out.println(low_list_date.get(tt)+"|"+low_list_price.get(tt));
    }

    for(int ii = 0; ii < high_list_date.size();ii++){
        System.out.print(high_list_date.get(ii)+"|");
        System.out.println(+high_list_price.get(ii));
    }

high_list_price.size() = 51 both before and after the .remove, yet high_list_date.size() goes from 51 to 50, why is that?

array.size()? In any case, did you actually remove anything? size() will return the current size. — Dave Newton
– Dave Newton, Commented Jan 27, 2012 at 18:10
How are you creating these lists? Are they backed by arrays? — Paul Tomblin
– Paul Tomblin, Commented Jan 27, 2012 at 18:11
I suspect you error does not come from the code you have pasted here. It must be something else. — ChrisJ
– ChrisJ, Commented Jan 27, 2012 at 18:12
The code you posted has no error in it (other than when size() returns 0). consider posting the code that you replaced with an ellipsis in the loops. — DwB
– DwB, Commented Jan 27, 2012 at 18:18
I suspect, given the methods you're calling from your array that you are actually using an ArrayList already. I don't remember remove or size being things you could use for an array. Is this correct? If not, your problem would probably stem from arrays not being re-sizable. You will need to figure out the new size needed for your array, create a new array and dump the information from the old array into the new array. As mentioned by previous posters, it would be easier to use an ArrayList or vector. — kelleystar
– kelleystar, Commented Jan 27, 2012 at 18:29

Mark Bolusmjak · Accepted Answer · 2012-01-27 18:12:22Z

2

If you iterate through ArrayLists backwards, you can delete the current element without worrying about what comes after.
Another option is to iterate through, make a list of things to delete, then delete those elements form the original list.

answered Jan 27, 2012 at 18:12

Mark Bolusmjak

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Jim Kiley · Accepted Answer · 2012-01-27 18:17:21Z

1

As an addition to the valid options provided by @z5h there, consider using the Iterator interface, which includes a remove() method that removes the item from the underlying collection without causing the kinds of problems that using Collection.remove() causes.

Using Iterator might help you walk through your collections in a more readable fashion, as well.

answered Jan 27, 2012 at 18:17

Jim Kiley

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最白目 · Accepted Answer · 2012-01-27 18:11:37Z

0

you may want to use an ArrayList instead of an plain array. It provides additional functions like remove(Object o)

answered Jan 27, 2012 at 18:11

最白目

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