Most efficient way to remove object from inside of an iterating ArrayList

Question

I'm trying to remove an object from an iterating ArrayList but cannot do so from inside of the loop, here is what I have at the moment

        for(Pearl pearl : this.pearls){
            pearl.onDraw(canvas);

            if(fish.isCollide(pearl)){
                this.pearls.remove(pearl);
            }
        }

The above code does not work if the ArrayList is larger than 1.

I was thinking of changing the code to something such as the following but would prefer to know if there is a simpler way.

       List<Pearl> pearls_delete = new ArrayList<Pearl>();


       for(Pearl pearl : this.pearls){
            pearl.onDraw(canvas);

            if(fish.isCollide(pearl)){
                pearls_delete.add(pearl);
            }
        }

        this.pearls.removeAll(pearls_delete);

Your solution is common one. There is no easier solution for this. — libik, Nov 11 '14 at 22:31
@libik That is not correct. See my solution with `Iterator` below — Jeff Storey, Nov 11 '14 at 22:39

score 9 · Accepted Answer · edited Nov 11 '14 at 22:40

9

Use an Iterator

Iterator<Pearl> iter = this.pearls.iterator();
while ( iter.hasNext() ) {
   Pearl pearl = iter.next();
   // logic
   iter.remove();
}

or simply

for (Iterator<Pearl> iter = pearls.iterator(); iter.hasNext();) {
   Pearl pearl = iter.next();
   // logic
   iter.remove();
}

edited Nov 11 '14 at 22:40

Bohemian

412,405
93
575
722

answered Nov 11 '14 at 22:38

Jeff Storey

56,312
72
233
406

Thanks, it's very pretty code – mk_89 Nov 11 '14 at 22:46

Most efficient way to remove object from inside of an iterating ArrayList

1 Answers1