Question

Is this going to cause unpredictable behavior?

 ArrayList<X> x = new ArrayList<>();
 //x.add(new X())...
f:
for(int i = 0; i < x.size() -1;)
{
      X y = x.get(i);
      for(int j = i + 1; j < x.size();)
       {
          if(a) {
           x.remove(j);
           continue;
          }
          if(b) {
           x.remove(i);
           continue f;
          }
          j++;
        }
       i++;
}

Answer 1

I don’t think it will be unpredictable, but your style seems wrong to me, so your approach is suspect.

Using a label is a bad idea, and deciding to use it shows that your approach is flawed.

You may want to look at this discussion about deleting on ArrayList, but basically, LinkedList would be fsster:

http://www.velocityreviews.com/forums/t587893-best-way-to-loop-through-arraylist-and-remove-elements-on-the-way.html

But, removing this way will work.

UPDATE:

Oops, just saw a couple of bugs:

      if(a) {
       x.remove(j);
       continue;
      }

OK, in this one, you will go back through the loop for j, but you didn’t increment j.

      if(b) {
       x.remove(i);
       continue f;
      }

This is the same for i.

So, you need a similar change to fix it:

for(int i = 0; i < x.size() -1; i++)

This way, when you hit continue then it will still go to the next element.