Question

I’m having a problem where I am trying to iterate through an arraylist which stores restaurant objects but the loop only goes through 3 of the five elements.

I created a test method to illustrate:

public void testLoop() {
        ArrayList<Eatery> test = new ArrayList<Eatery>();
        test = eateriesListDefault;
        for(Eatery e : test) {
            MyLog.e(TAG, "Name: " + e.getName());
        }
        for (int i = 0; i < eateriesListDefault.size(); i++) {
            MyLog.e(TAG, "Name " + test.get(i).getName());
            test.remove(i);
        }
        for(Eatery e : test) {
            MyLog.e(TAG, "Name " + e.getName());
        }
    }

Here test will have 5 eatery objects in it. The first loop succesfully prints 5 of 5 names.
The second loop only removes 3 of the eateries and therefore the last loop prints two names.

I have tried using

for(Eatery e : eateriesListDefault) {
            MyLog.e(TAG, "Name: " + e.getName());
            test.remove(e);
}

in place of the second loop, however I get a concurrent access error.

Does anyone know what I am doing wrong?

Answer 1

You’re calling eateriesListDefault.size() in each loop iteration. At the same time, you’re calling test.remove(i) which is shorting the array by one every iteration. Your loop is essentially doing this:

1. i = 0
   size = 5
   Keep going

2. i = 1
   size = 4
   Keep going

3. i = 2
   size = 3
   Keep going

4. i = 3
   size = 2
   stop

If you’re goal was to print out the first element of the array then remove it, you could probably get there by this loop:

while(!eateriesListDefault.isEmpty()) {
   MyLog.e(TAG, "Name " + test.get(0).getName());
   test.remove(0);
}